Java^TM Secure Socket Extension (JSSE)

Data that travels across a network can easily be accessed by someone who is not the intended recipient. When the data includes private information, such as passwords and credit card numbers, steps must be taken to make the data unintelligible to unauthorized parties. It is also important to ensure the data has not been modified, either intentionally or unintentionally, during transport. The Secure Sockets Layer (SSL) and Transport Layer Security (TLS) protocols were designed to help protect the privacy and integrity of data while it is transferred across a network.
The Java Secure Socket Extension (JSSE) enables secure Internet communications. It provides a framework and an implementation for a Java version of the SSL and TLS protocols and includes functionality for data encryption, server authentication, message integrity, and optional client authentication. Using JSSE, developers can provide for the secure passage of data between a client and a server running any application protocol, such as Hypertext Transfer Protocol (HTTP), Telnet, or FTP, over TCP/IP. (For an introduction to SSL, see Secure Sockets Layer (SSL) Protocol Overview.)
By abstracting the complex underlying security algorithms and "handshaking" mechanisms, JSSE minimizes the risk of creating subtle, but dangerous security vulnerabilities. Furthermore, it simplifies application development by serving as a building block which developers can integrate directly into their applications.
JSSE was previously an optional package (standard extension) to the Java^TM 2 SDK, Standard Edition (J2SDK) versions 1.2 and 1.3. JSSE has now been integrated into the J2SDK, v 1.4.
JSSE provides both an application programming interface (API) framework and an implementation of that API. The JSSE API supplements the "core" cryptographic services defined in the Java 2 SDK, v 1.4 java.security and java.net packages by providing extended networking socket classes, trust managers, key managers, SSLContexts, and a socket factory framework for encapsulating socket creation behavior. (It also provides a limited public key certificate API that is compatible with Java Development Kit (JDK) 1.1-based platforms. However, please note that this limited javax.security.cert certificate API is provided only for backward compatibility with JSSE 1.0.x and should not be used. Instead, use the standard java.security.cert certificate API.)
The JSSE API is capable of supporting SSL versions 2.0 and 3.0 and Transport Layer Security (TLS) 1.0. These security protocols encapsulate a normal bidirectional stream socket and the JSSE API adds transparent support for authentication, encryption, and integrity protection. The JSSE implementation in the J2SDK, v 1.4 implements SSL 3.0 and TLS 1.0. It does not implement SSL 2.0.
As mentioned above, JSSE is a security component of the Java 2 platform, and is based on the same design principles found elsewhere in the Java Cryptography Architecture (JCA) framework. This framework for cryptography-related security components allows them to have implementation independence and, whenever possible, algorithm independence. JSSE uses the same "provider" architecture defined in the JCA.
Other security components in the Java 2 platform include the Java Cryptography Extension (JCE), the Java Authentication and Authorization Service (JAAS), and the Java Security Tools. JSSE encompasses many of the same concepts and algorithms as those in JCE but automatically applies them underneath a simple stream socket API.
The JSSE APIs were designed to allow other SSL/TLS protocol and Public Key Infrastructure (PKI) implementations to be plugged in seamlessly. Developers can also provide alternate logic for determining if remote hosts should be trusted or what authentication key material should be sent to a remote host.

Note: While the JSSE APIs allow the replacement of the underlying implementations (also known as "pluggability"), due to U.S. export restrictions this release does not permit you to replace the SSL/TLS algorithms. The TrustManagerFactory and KeyManagerFactory are still fully pluggable.

Features and Benefits

JSSE includes the following important features:

Implemented in 100% Pure Java

Can be exported to most countries

Provides API support for SSL versions 2.0 and 3.0, and implementation of SSL version 3.0

Provides API support and an implementation for TLS version 1.0

Includes classes that can be instantiated to create secure channels (SSLSocket and SSLServerSocket)

Provides support for cipher suite negotiation, which is part of the SSL handshaking used to initiate or verify secure communications

Provides support for client and server authentication, which is part of the normal SSL handshaking

Provides support for Hypertext Transfer Protocol (HTTP) encapsulated in the SSL protocol (HTTPS), which allows access to data such as web pages using HTTPS

Provides server session management APIs to manage memory-resident SSL sessions

Includes code licensed from RSA Data Security Inc. such as RSA and RC4

Provides support for several cryptographic algorithms commonly used in cipher suites, including those listed in the following table:

Cryptographic Functionality Available With JSSE

Cryptographic Algorithm *

Cryptographic Process

Key Lengths (Bits)

RSA

Authentication and key exchange

2048 (authentication)
2048 (key exchange)
512 (key exchange)

RC4

Bulk encryption

128
128 (40 effective)

DES

Bulk encryption

64 (56 effective)
64 (40 effective)

Triple DES

Bulk encryption

192 (112 effective)

Diffie-Hellman

Key agreement

1024
512

DSA

Authentication

1024

* Note: The cryptographic algorithms shipped in the SunJSSE provider are not registered with the Java Cryptography Architecture (JCA) provider framework, and are not available for use by other applications.
** Note: The SunJSSE implementation uses the Java^TM Cryptography Extension (JCE) AES cipher for AES-based ciphersuites.

JSSE Standard API

The JSSE standard API, available in the javax.net, javax.net.ssl and javax.security.cert packages, covers:

Secure (SSL) sockets and server sockets.

Factories for creating sockets, server sockets, SSL sockets, and SSL server sockets. Using socket factories you can encapsulate socket creation and configuration behavior.

A class representing a secure socket context that acts as a factory for secure socket factories.

Key and trust manager interfaces (including X.509-specific key and trust managers), and factories for creating them.

A class for secure HTTP URL connections.

A public key certificate API compatible with JDK 1.1-based platforms.

SunJSSE Provider

The J2SDK, v 1.4 release comes with a JSSE provider named "SunJSSE", which comes pre-installed and pre-registered with the JCA. This provider supplies the following cryptographic services:

RSA support for the signature-related JCA features of the Java 2 platform.

An implementation of the SSL 3.0 and TLS 1.0 security protocols.

An implementation of the most common SSL and TLS cipher suites which encompass a combination of authentication, key agreement, encryption and integrity protection.

An implementation of an X.509-based key manager which chooses appropriate authentication keys from a standard JCA KeyStore.

An implementation of an X.509-based trust manager which implements rules for certificate chain path validation.

A read-only implementation of PKCS12 as JCA keystore type "pkcs12".

The following table lists the cipher suites that SunJSSE supports and those that are enabled by default.

Supported Cipher Suites in Default Preference Order

Name Enabled by Default New in
J2SE 1.4.2

SSL_RSA_WITH_RC4_128_MD5 X

SSL_RSA_WITH_RC4_128_SHA X

TLS_RSA_WITH_AES_128_CBC_SHA X X

TLS_DHE_RSA_WITH_AES_128_CBC_SHA X X

TLS_DHE_DSS_WITH_AES_128_CBC_SHA X X

SSL_RSA_WITH_3DES_EDE_CBC_SHA X

SSL_DHE_RSA_WITH_3DES_EDE_CBC_SHA X X

SSL_DHE_DSS_WITH_3DES_EDE_CBC_SHA X

SSL_RSA_WITH_DES_CBC_SHA X

SSL_DHE_RSA_WITH_DES_CBC_SHA X X

SSL_DHE_DSS_WITH_DES_CBC_SHA X

SSL_RSA_EXPORT_WITH_RC4_40_MD5 X

SSL_RSA_EXPORT_WITH_DES40_CBC_SHA X X

SSL_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA X X

SSL_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA X

TLS_RSA_WITH_AES_256_CBC_SHA * X

TLS_DHE_RSA_WITH_AES_256_CBC_SHA * X

TLS_DHE_DSS_WITH_AES_256_CBC_SHA * X

SSL_RSA_WITH_NULL_MD5

SSL_RSA_WITH_NULL_SHA

SSL_DH_anon_WITH_RC4_128_MD5

TLS_DH_anon_WITH_AES_128_CBC_SHA X

TLS_DH_anon_WITH_AES_256_CBC_SHA * X

SSL_DH_anon_WITH_3DES_EDE_CBC_SHA

SSL_DH_anon_WITH_DES_CBC_SHA

SSL_DH_anon_EXPORT_WITH_RC4_40_MD5

SSL_DH_anon_EXPORT_WITH_DES40_CBC_SHA

* Requires installation of the JCE Unlimited Strength Jurisdiction Policy Files. See http://java.sun.com/j2se/1.4.2/download.html

What's New
This section highlights the differences between the JSSE in releases 1.4.2 and 1.4 of the Java 2 Platform and earlier releases.
What's New in JSSE in the J2SDK, v 1.4.2

The following changes were introduced in the JSSE in version 1.4.2 of the Java 2 platform:

The SunJSSE implementation now supports a number of additional ciphersuites. They include ciphersuites using AES as a symmetric cipher and ephemeral Diffie-Hellman with RSA authentication (DHE_RSA). For more information, see the table of "Supported Cipher Suites" in the section SunJSSE Provider.

In addition to the simple X.509 based trustmanager previously available in the SunJSSE provider, it now supports a second, PKIX-compliant trust manager. It is implemented using the default CertPath PKIX implementation. For more information, see the section TrustManagerFactory Class.

What's New in JSSE in the J2SDK, v 1.4
Here are the differences between JSSE 1.0.2 and the JSSE in the J2SDK, v 1.4:

JSSE Is Now in J2SDK

javax.security.cert Should Not Be Used

SunJSSE Provider Can Use JCE Providers for Encryption

Classes Formerly in com.sun.net.ssl Are Now in javax.net.ssl

New Methods and Interface

Changed Classes and Methods

Documentation Improvements

JSSE Is Now in J2SDK

JSSE was previously an optional package (extension) to the Java^TM 2 SDK, Standard Edition (J2SDK), versions 1.2 and 1.3. JSSE has now been integrated into the J2SDK, v 1.4. The SunJSSE provider is also included and is pre-registered in the java.security security properties file included with the J2SDK, v 1.4.

javax.security.cert Should Not Be Used

JSSE was developed before the java.security.cert package was widely available, so a supplemental certificate package was introduced in earlier versions of JSSE called javax.security.cert. JSSE is now bundled into the J2SDK itself and takes advantage of the more complete certificate API available in the java.security.cert package. All new applications should use java.security.cert. The javax.security.cert package exists only for backward compatibility with previous JSSE releases, and should no longer be used.

SunJSSE Provider Can Use JCE Providers for Encryption

The SunJSSE provider can now make use of JCE providers for encryption algorithms. Previously, SunJSSE always made use of internal implementations for encryption algorithms. Now implementations from providers with a higher preference order than SunJSSE are used if available. See Customizing the Encryption Algorithm Providers for more information.

Classes Formerly in com.sun.net.ssl Are Now in javax.net.ssl

All of the classes and interfaces formerly (in JSSE 1.0.x) in the com.sun.net.ssl package have been promoted to the javax.net.ssl package. The old com.sun.net.ssl classes and interfaces still exist and are unchanged, but are included in the SunJSSE provider only for backward compatibility. What is provided is actually "wrappers" that reference the new javax.net.ssl classes/interfaces.
The implementation now uses javax.net.ssl.SSLPermissions rather than com.sun.net.ssl.SSLPermission, so any policy files that used to mention com.sun.net.ssl.SSLPermission should now use javax.net.ssl.SSLPermissions instead.

New Methods and Interfaces
New methods setWantClientAuth and getWantClientAuth were added to SSLSocket and SSLServerSocket (in javax.net.ssl) to enable optional client authentication.
The method SSLContext.getInstance(protocol) returns socket factories which support at least the specified protocol. New methods setEnabledProtocols and getEnabledProtocols were added to SSLSocket and SSLServerSocket to further refine which protocols are enabled for use on this connection. Another new method getSupportedProtocols was added to SSLSocket and SSLServerSocket; getSupportedProtocols can be used to obtain the protocol versions that can be enabled for use on an SSL connection. The new method getProtocol was added to SSLSession for retrieving the standard name of the protocol used in the session.
SocketFactory and ServerSocketFactory have new methods createSocket and createServerSocket, respectively, for creating unconnected sockets.
New methods getServerSessionContext and getClientSessionContext were added to SSLContext. They allow the developer to obtain the set of SSL client or server sessions available for reuse during handshaking.
New methods setSessionTimeout and getSessionTimeout were added to SSLSessionContext. They allow the developer to control when sessions timeout and become invalid. New methods setSessionCacheSize and getSessionCacheSize were also added to control how many sessions should be cached for reuse by future connections.
New methods were added to HttpsURLConnection, SSLSession, and HandshakeCompletedEvent (all in javax.net.ssl) that allow you to get generic Java 2 java.security.cert.Certificate certificates in addition to the javax.security.cert.X509Certificate certificates returned by previously-existing methods. The new methods are
SSLSession.getPeerCertificates
HandshakeCompletedEvent.getPeerCertificates
HttpsURLConnection.getServerCertificates
A getLocalCertificates method was added to SSLSession, HandshakeCompletedEvent, and HttpsURLConnection. This method returns the certificate(s) that were sent to the peer during handshaking. This provides a way to determine what certificate chain was actually used to authenticate the local side of a given SSL session.
A new interface ManagerFactoryParameters was added as a base interface that providers can extend if they need KeyManagerFactory and/or TrustManagerFactory initialization parameters other than the ones that can be passed to the KeyStore-based init methods of those classes. The KeyManagerFactory and TrustManagerFactory classes each have a new init method that takes a ManagerFactoryParameters argument. Users of a particular provider are expected to pass an implementation of the appropriate ManagerFactoryParameters as defined by the provider.
Changed Classes and Methods
When the com.sun APIs were prepared for inclusion in the javax namespace, some API limitations were corrected in the javax version. The old com.sun.* APIs found in the previous JSSE optional packages are still the same and have not changed. The changes described in the paragraphs below only apply to the new javax.* classes of the same name.
The HttpsURLConnection constructor has been changed to be protected. This was done for consistency with other similar classes such as URLConnection, JarURLConnection, and HttpURLConnection, all in the java.net package. Another change to the HttpsURLConnection class is that the method that returned javax.security.cert certificates was removed.
Hostname verification has been redone to be more generic. The negotiated SSLSession is now passed to the verifier's verify method instead of the hostname contained in the received certificates. The SSLSession can then be queried for the negotiated ciphersuite, the exchanged certificates, and so on.
The X509TrustManager isClientTrusted and isServerTrusted methods were renamed checkClientTrusted and checkServerTrusted, respectively. If the certificate chain is not trusted by this TrustManager, the checkClientTrusted and checkServerTrusted methods throw an exception rather than return a boolean (like the former methods did). This allows implementations to ascertain the underlying cause for failure of the trust decision. The checks done by checkClientTrusted and checkServerTrusted include verifying that the certificate is used for an operation that complies with the certificate's key usage extension. To properly perform this check, it is necessary to pass the authentication type to these methods, and so a String authType argument has been added.
One parameter has been added and one changed for the X509KeyManager chooseClientAlias and chooseServerAlias methods. A Socket socket parameter was added to both methods for specifying the socket to be used for the connection. The keytype parameter for the chooseClientAlias method was changed from a single String to an array of Strings specifying the key algorithm type name(s), ordered with the most-preferred type first. For example, the chooseClientAlias method signature used to be
  chooseClientAlias(String keyType, Principal[] issuers)
and now it is
  chooseClientAlias(String[] keyType, Principal[] issuers, 
                    Socket socket)
The parameters help decide which certificate(s) to use when connecting to a remote host.
The default key manager factory algorithm name has been changed from sun.ssl.keymanager.type to ssl.KeyManagerFactory.algorithm. Similarly, the default trust manager factory algorithm name has been changed from sun.ssl.trustmanager.type to ssl.TrustManagerFactory.algorithm.
Documentation Improvements

This JSSE Reference Guide was updated and expanded.
There were a number of minor clarifications made to the JSSE javadocs, primarily when discussing illegal arguments and implied behavior.
Related Documentation

Java Secure Socket Extension Documentation

The JSSE home page, with links to JavaOne^SM conference slides, the JSSE FAQ, legal issues, etc.:
http://java.sun.com/products/jsse/

Archive of API-related questions and answers posted to Sun's Java Security team through java-security@sun.com:
http://archives.java.sun.com/archives/java-security.html
Note: The above mailing list is not a subscription list or a support mechanism. It is simply a one-way channel that you can use to send comments to the Java 2 Standard Edition security team.

JSSE API documentation:

javax.net package
javax.net.ssl package
javax.security.cert package

Java 2 Platform Security Documentation

Java 2 security homepage:
http://java.sun.com/security/

The Java^TM Certification Path API Programmer's Guide:
http://java.sun.com/j2se/1.4.2/docs/guide/security/certpath/CertPathProgGuide.html

Links to more Java 2 platform security documents:
http://java.sun.com/j2se/1.4.2/docs/guide/security/

Tutorial for Java 2 platform security:
http://java.sun.com/docs/books/tutorial/security1.2/

Book on Java 2 platform security:
Inside Java 2 Platform Security: Architecture, API Design, and Implementation by Li Gong. Addison Wesley Longman, Inc., 1999. ISBN: 0201310007.

Export Issues Related to Cryptography

For information on U.S. encryption policies, refer to these Web sites:

U.S. Department of Commerce:
http://www.doc.gov/

Export Policy Resource Page:
http://www.crypto.com/

Computer Systems Public Policy:
http://www.cspp.org/

Federal Information Processing Standards Publications (FIPS PUBS) homepage, which has links to the Data Encryption Standard (DES):
http://www.itl.nist.gov/fipspubs/

Revised U.S. Encryption Export Control Regulations:
http://www.epic.org/crypto/export_controls/regs_1_00.html

Cryptography Documentation

Online resources:

Dr. Rivest's Cryptography and Security page:
http://theory.lcs.mit.edu/~rivest/crypto-security.html

Books:

Applied Cryptography, Second Edition by Bruce Schneier. John Wiley and Sons, Inc., 1996.

Cryptography Theory and Practice by Doug Stinson. CRC Press, Inc., 1995.

Cryptography & Network Security: Principles & Practice by William Stallings. Prentice Hall, 1998.

Secure Sockets Layer Documentation

Online resources:

Documentation from Netscape about SSL:
http://developer.netscape.com/docs/manuals/security.html#SSL

Introduction to SSL from Sun™ ONE Software (formerly known as iPlanet):
http://www.iplanet.com/developer/docs/articles/security/
ssl.html

The SSL Protocol version 3.0 Internet Draft:
http://home.netscape.com/eng/ssl3/ssl-toc.html

The TLS Protocol version 1.0 Internet Draft:
http://www.ietf.org/rfc/rfc2246.txt

"HTTP Over TLS" Information RFC:
http://www.ietf.org/rfc/rfc2818.txt

Books:

SSL and TLS: Designing and Building Secure Systems by Eric Rescorla. Addison Wesley Professional, 2000.

SSL and TLS Essentials: Securing the Web by Stephen Thomas. John Wiley and Sons, Inc., 2000.

Java 2 Network Security, Second Edition, by Marco Pistoia, Duane F Reller, Deepak Gupta, Milind Nagnur, and Ashok K Ramani. Prentice Hall, 1999. Copyright 1999 International Business Machines.

Cryptographic Functionality Available With JSSE
Cryptographic Algorithm *	Cryptographic Process	Key Lengths (Bits)
RSA	Authentication and key exchange	2048 (authentication) 2048 (key exchange) 512 (key exchange)
RC4	Bulk encryption	128 128 (40 effective)
DES	Bulk encryption	64 (56 effective) 64 (40 effective)
Triple DES	Bulk encryption	192 (112 effective)
Diffie-Hellman	Key agreement	1024 512
DSA	Authentication	1024

Supported Cipher Suites in Default Preference Order
Name	Enabled by Default	New in J2SE 1.4.2
`SSL_RSA_WITH_RC4_128_MD5`	X
`SSL_RSA_WITH_RC4_128_SHA`	X
`TLS_RSA_WITH_AES_128_CBC_SHA`	X	X
`TLS_DHE_RSA_WITH_AES_128_CBC_SHA`	X	X
`TLS_DHE_DSS_WITH_AES_128_CBC_SHA`	X	X
`SSL_RSA_WITH_3DES_EDE_CBC_SHA`	X
`SSL_DHE_RSA_WITH_3DES_EDE_CBC_SHA`	X	X
`SSL_DHE_DSS_WITH_3DES_EDE_CBC_SHA`	X
`SSL_RSA_WITH_DES_CBC_SHA`	X
`SSL_DHE_RSA_WITH_DES_CBC_SHA`	X	X
`SSL_DHE_DSS_WITH_DES_CBC_SHA`	X
`SSL_RSA_EXPORT_WITH_RC4_40_MD5`	X
`SSL_RSA_EXPORT_WITH_DES40_CBC_SHA`	X	X
`SSL_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA`	X	X
`SSL_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA`	X
`TLS_RSA_WITH_AES_256_CBC_SHA *`		X
`TLS_DHE_RSA_WITH_AES_256_CBC_SHA *`		X
`TLS_DHE_DSS_WITH_AES_256_CBC_SHA *`		X
`SSL_RSA_WITH_NULL_MD5`
`SSL_RSA_WITH_NULL_SHA`
`SSL_DH_anon_WITH_RC4_128_MD5`
`TLS_DH_anon_WITH_AES_128_CBC_SHA`		X
`TLS_DH_anon_WITH_AES_256_CBC_SHA *`		X
`SSL_DH_anon_WITH_3DES_EDE_CBC_SHA`
`SSL_DH_anon_WITH_DES_CBC_SHA`
`SSL_DH_anon_EXPORT_WITH_RC4_40_MD5`
`SSL_DH_anon_EXPORT_WITH_DES40_CBC_SHA`

Terms and Definitions

There are several terms relating to cryptography that are used within this document. This section defines some of these terms.
Authentication
Authentication is the process of confirming the identity of a party with whom one is communicating.
Cipher Suite
A cipher suite is a combination of cryptographic parameters that define the security algorithms and key sizes used for authentication, key agreement, encryption, and integrity protection.
Certificate
A certificate is a digitally signed statement vouching for the identity and public key of an entity (person, company, etc.). Certificates can either be self-signed or issued by a Certification Authority (CA). Certification Authorities are entities that are trusted to issue valid certificates for other entities. Well-known CAs include VeriSign, Entrust, and GTE CyberTrust. X509 is a common certificate format, and they can be managed by the JDK's keytool.
Cryptographic Hash Function
A cryptographic hash function is similar to a checksum. Data is processed with an algorithm that produces a relatively small string of bits called a hash. A cryptographic hash function has three primary characteristics: it is a one-way function, meaning that it is not possible to produce the original data from the hash; a small change in the original data produces a large change in the resulting hash; and it does not require a cryptographic key.
Cryptographic Service Provider
In the JCA, implementations for various cryptographic algorithms are provided by cryptographic service providers, or "providers" for short. Providers are essentially packages that implement one or more engine classes for specific algorithms. An engine class defines a cryptographic service in an abstract fashion without a concrete implementation.
Digital Signature
A digital signature is the digital equivalent of a handwritten signature. It is used to ensure that data transmitted over a network was sent by whoever claims to have sent it and that the data has not been modified in transit. For example, an RSA-based digital signature is calculated by first computing a cryptographic hash of the data and then encrypting the hash with the sender's private key.
Encryption and Decryption
Encryption is the process of using a complex algorithm to convert an original message, or cleartext, to an encoded message, called ciphertext, that is unintelligible unless it is decrypted. Decryption is the inverse process of producing cleartext from ciphertext. The algorithms used to encrypt and decrypt data typically come in two categories: secret key (symmetric) cryptography and public key (asymmetric) cryptography.
Handshake Protocol
The negotiation phase during which the two socket peers agree to use a new or existing session. The handshake protocol is a series of messages exchanged over the record protocol. At the end of the handshake new connection-specific encryption and integrity protection keys are generated based on the key agreement secrets in the session.
Key Agreement
Key agreement is a protocol by which 2 or more parties can establish the same cryptographic keys, without having to exchange any secret information in the clear. Examples include RSA and Diffie-Hellman.

Key Managers and Trust Managers

Key managers (see KeyManagerFactory) and trust managers (see TrustManagerFactory) use keystores for their key material. A key manager manages a keystore and supplies public keys to others as needed, e.g., for use in authenticating the user to others. A trust manager makes decisions about who to trust based on information in the truststore it manages.
Keystores and Truststores

A keystore is a database of key material. Key material is used for a variety of purposes, including authentication and data integrity. There are various types of keystores available, including "PKCS12" and Sun's "JKS."
Generally speaking, keystore information can be grouped into two different categories: key entries and trusted certificate entries. A key entry consists of an entity's identity and its private key, and can be used for a variety of cryptographic purposes. In contrast, a trusted certificate entry only contains a public key in addition to the entity's identity. Thus, a trusted certificate entry can not be used where a private key is required, such as in a javax.net.ssl.KeyManager. In the J2SDK implementation of "JKS", a keystore may contain both key entries and trusted certificate entries.
A truststore is a keystore which is used when making decisions about what to trust. If you receive some data from an entity that you already trust, and if you can verify that the entity is the one it claims to be, then you can assume that the data really came from that entity.
An entry should only be added to a truststore if the user makes a decision to trust that entity. By either generating a keypair or by importing a certificate, the user has given trust to that entry, and thus any entry in the keystore is considered a trusted entry.
It may be useful to have two different keystore files: one containing just your key entries, and the other containing your trusted certificate entries, including Certification Authority (CA) certificates. The former contains private information, while the latter does not. Using two different files instead of a single keystore file provides for a cleaner separation of the logical distinction between your own certificates (and corresponding private keys) and others' certificates. You could provide more protection for your private keys if you store them in a keystore with restricted access, while providing the trusted certificates in a more publicly accessible keystore if needed.
Message Authentication Code
A Message Authentication Code (MAC) provides a way to check the integrity of information transmitted over or stored in an unreliable medium, based on a secret key. Typically, MACs are used between two parties that share a secret key in order to validate information transmitted between these parties.
A MAC mechanism that is based on cryptographic hash functions is referred to as HMAC. HMAC can be used with any cryptographic hash function, such as Message Digest 5 (MD5) and Secure Hash Algorithm (SHA), in combination with a secret shared key. HMAC is specified in RFC 2104.
Public Key Cryptography
Public key cryptography uses an encryption algorithm in which two keys are produced. One key is made public while the other is kept private. The public key and the private key are cryptographic inverses; what one key encrypts only the other key can decrypt. Public key cryptography is also called asymmetric cryptography.
Record Protocol
The record protocol packages all data whether application-level or as part of the handshake process into discrete records of data much like a TCP stream socket converts an application byte stream into network packets. The individual records are then protected by the current encryption and integrity protection keys.
Secret Key Cryptography
Secret key cryptography uses an encryption algorithm in which the same key is used both to encrypt and decrypt the data. Secret key cryptography is also called symmetric cryptography.
Session
A session is a named collection of state information including authenticated peer identity, cipher suite, and key agreement secrets which are negotiated through a secure socket handshake and which can be shared among multiple secure socket instances.
Trust Managers
See Key Managers and Trust Managers.
Truststore
See Keystores and Truststores.

Secure Sockets Layer (SSL) Protocol Overview

Secure Sockets Layer (SSL) is the most widely used protocol for implementing cryptography on the Web. SSL uses a combination of cryptographic processes to provide secure communication over a network. This section provides an introduction to SSL and the cryptographic processes it uses.
SSL provides a secure enhancement to the standard TCP/IP sockets protocol used for Internet communications. As shown in the "TCP/IP Protocol Stack With SSL" figure below, the secure sockets layer is added between the transport layer and the application layer in the standard TCP/IP protocol stack. The application most commonly used with SSL is Hypertext Transfer Protocol (HTTP), the protocol for Internet Web pages. Other applications, such as Net News Transfer Protocol (NNTP), Telnet, Lightweight Directory Access Protocol (LDAP), Interactive Message Access Protocol (IMAP), and File Transfer Protocol (FTP), can be used with SSL as well.
Note: There is currently no standard for secure FTP.

TCP/IP Protocol Stack With SSL

TCP/IP Layer

Protocol

Application Layer

    HTTP, NNTP, Telnet, FTP, etc.

Secure Sockets Layer

    SSL

Transport Layer

    TCP

Internet Layer

    IP

SSL was developed by Netscape in 1994, and with input from the Internet community, has evolved to become a standard. It is now under the control of the international standards organization, the Internet Engineering Task Force (IETF). The IETF has renamed SSL to Transport Layer Security (TLS), and released the first specification, version 1.0, in January 1999. TLS 1.0 is a modest upgrade to the most recent version of SSL, version 3.0. The differences between SSL 3.0 and TLS 1.0 are minor.
Why Use SSL?

Transferring sensitive information over a network can be risky due to the following three issues:

You cannot always be sure that the entity with whom you are communicating is really who you think it is.

Network data can be intercepted, so it is possible that it can be read by an unauthorized third party, sometimes known as an attacker.

If an attacker can intercept the data, the attacker may be able to modify the data before sending it on to the receiver.

SSL addresses each of these issues. It addresses the first issue by optionally allowing each of two communicating parties to ensure the identity of the other party in a process called authentication. Once the parties are authenticated, SSL provides an encrypted connection between the two parties for secure message transmission. Encrypting the communication between the two parties provides privacy and therefore addresses the second issue. The encryption algorithms used with SSL include a secure hash function, which is similar to a checksum. This ensures that data is not modified in transit. The secure hash function addresses the third issue of data integrity.
Note, both authentication and encryption are optional, and depend on the the negotiated cipher suites between the two entities.
The most obvious example of when you would use SSL is in an e-commerce transaction. In an e-commerce transaction, it would be foolish to assume that you can guarantee the identity of the server with whom you are communicating. It would be easy enough for someone to create a phony Web site promising great services if only you enter your credit card number. SSL allows you, the client, to authenticate the identity of the server. It also allows the server to authenticate the identity of the client, although in Internet transactions, this is seldom done.
Once the client and the server are comfortable with each other's identity, SSL provides privacy and data integrity through the encryption algorithms it uses. This allows sensitive information, such as credit card numbers, to be transmitted securely over the Internet.
While SSL provides authentication, privacy, and data integrity, it does not provide non-repudiation services. Non-repudiation means that an entity that sends a message cannot later deny that they sent it. When the digital equivalent of a signature is associated with a message, the communication can later be proved. SSL alone does not provide non-repudiation.

How SSL Works

One of the reasons SSL is effective is that it uses several different cryptographic processes. SSL uses public key cryptography to provide authentication, and secret key cryptography and digital signatures to provide for privacy and data integrity. Before you can understand SSL, it is helpful to understand these cryptographic processes.
Cryptographic Processes

The primary purpose of cryptography is to make it difficult for an unauthorized third party to access and understand private communication between two parties. It is not always possible to restrict all unauthorized access to data, but private data can be made unintelligible to unauthorized parties through the process of encryption. Encryption uses complex algorithms to convert the original message, or cleartext, to an encoded message, called ciphertext. The algorithms used to encrypt and decrypt data that is transferred over a network typically come in two categories: secret key cryptography and public key cryptography. These forms of cryptography are explained in the following subsections.
Both secret key cryptography and public key cryptography depend on the use of an agreed-upon cryptographic key or pair of keys. A key is a string of bits that is used by the cryptographic algorithm or algorithms during the process of encrypting and decrypting the data. A cryptographic key is like a key for a lock: only with the right key can you open the lock.
Safely transmitting a key between two communicating parties is not a trivial matter. A public key certificate allows a party to safely transmit its public key, while ensuring the receiver of the authenticity of the public key. Public key certificates are described in a later section.
In the descriptions of the cryptographic processes that follow, we use the conventions used by the security community: we label the two communicating parties with the names Alice and Bob. We call the unauthorized third party, also known as the attacker, Charlie.
Secret Key Cryptography

With secret key cryptography, both communicating parties, Alice and Bob, use the same key to encrypt and decrypt the messages. Before any encrypted data can be sent over the network, both Alice and Bob must have the key and must agree on the cryptographic algorithm that they will use for encryption and decryption.
One of the major problems with secret key cryptography is the logistical issue of how to get the key from one party to the other without allowing access to an attacker. If Alice and Bob are securing their data with secret key cryptography, and if Charlie gains access to their key, Charlie can understand any secret messages he intercepts between Alice and Bob. Not only can Charlie decrypt Alice's and Bob's messages, but he can also pretend that he is Alice and send encrypted data to Bob. Bob will not know that the message came from Charlie, not Alice.
Once the problem of secret key distribution is solved, secret key cryptography can be a valuable tool. The algorithms provide excellent security and encrypt data relatively quickly. The majority of the sensitive data sent in an SSL session is sent using secret key cryptography.
Secret key cryptography is also called symmetric cryptography because the same key is used to both encrypt and decrypt the data. Well-known secret key cryptographic algorithms include the Data Encryption Standard (DES), triple-strength DES (3DES), Rivest Cipher 2 (RC2), and Rivest Cipher 4 (RC4).

Public Key Cryptography

Public key cryptography solves the logistical problem of key distribution by using both a public key and a private key. The public key can be sent openly through the network while the private key is kept private by one of the communicating parties. The public and the private keys are cryptographic inverses of each other; what one key encrypts, the other key will decrypt.
Let's assume that Bob wants to send a secret message to Alice using public key cryptography. Alice has both a public key and a private key, so she keeps her private key in a safe place and sends her public key to Bob. Bob encrypts the secret message to Alice using Alice's public key. Alice can later decrypt the message with her private key.
If Alice encrypts a message using her private key and sends the encrypted message to Bob, Bob can be sure that the data he receives comes from Alice; if Bob can decrypt the data with Alice's public key, the message must have been encrypted by Alice with her private key, and only Alice has Alice's private key. The problem is that anybody else can read the message as well because Alice's public key is public. While this scenario does not allow for secure data communication, it does provide the basis for digital signatures. A digital signature is one of the components of a public key certificate, and is used in SSL to authenticate a client or a server. Public key certificates and digital signatures are described in later sections.
Public key cryptography is also called asymmetric cryptography because different keys are used to encrypt and decrypt the data. A well known public key cryptographic algorithm often used with SSL is the Rivest Shamir Adleman (RSA) algorithm. Another public key algorithm used with SSL that is designed specifically for secret key exchange is the Diffie-Hellman (DH) algorithm. Public key cryptography requires extensive computations, making it very slow. It is therefore typically used only for encrypting small pieces of data, such as secret keys, rather than for the bulk of encrypted data communications.

A Comparison Between Secret Key and Public Key Cryptography

Both secret key cryptography and public key cryptography have strengths and weaknesses. With secret key cryptography, data can be encrypted and decrypted quickly, but since both communicating parties must share the same secret key information, the logistics of exchanging the key can be a problem. With public key cryptography, key exchange is not a problem since the public key does not need to be kept secret, but the algorithms used to encrypt and decrypt data require extensive computations, and are therefore very slow.

Public Key Certificates

A public key certificate provides a safe way for an entity to pass on its public key to be used in asymmetric cryptography. The public key certificate avoids the following situation: if Charlie creates his own public key and private key, he can claim that he is Alice and send his public key to Bob. Bob will be able to communicate with Charlie, but Bob will think that he is sending his data to Alice.
A public key certificate can be thought of as the digital equivalent of a passport. It is issued by a trusted organization and provides identification for the bearer. A trusted organization that issues public key certificates is known as a certificate authority (CA). The CA can be likened to a notary public. To obtain a certificate from a CA, one must provide proof of identity. Once the CA is confident that the applicant represents the organization it says it represents, the CA signs the certificate attesting to the validity of the information contained within the certificate.
A public key certificate contains several fields, including:

Issuer - The issuer is the CA that issued the certificate. If a user trusts the CA that issues a certificate, and if the certificate is valid, the user can trust the certificate.

Period of validity - A certificate has an expiration date, and this date is one piece of information that should be checked when verifying the validity of a certificate.

Subject - The subject field includes information about the entity that the certificate represents.

Subject's public key - The primary piece of information that the certificate provides is the subject's public key. All the other fields are provided to ensure the validity of this key.

Signature - The certificate is digitally signed by the CA that issued the certificate. The signature is created using the CA's private key and ensures the validity of the certificate. Because only the certificate is signed, not the data sent in the SSL transaction, SSL does not provide for non-repudiation.

If Bob only accepts Alice's public key as valid when she sends it in a public key certificate, Bob will not be fooled into sending secret information to Charlie when Charlie masquerades as Alice.
Multiple certificates may be linked in a certificate chain. When a certificate chain is used, the first certificate is always that of the sender. The next is the certificate of the entity that issued the sender's certificate. If there are more certificates in the chain, each is that of the authority that issued the previous certificate. The final certificate in the chain is the certificate for a root CA. A root CA is a public certificate authority that is widely trusted. Information for several root CAs is typically stored in the client's Internet browser. This information includes the CA's public key. Well-known CAs include VeriSign, Entrust, and GTE CyberTrust.

Cryptographic Hash Functions

When sending encrypted data, SSL typically uses a cryptographic hash function to ensure data integrity. The hash function prevents Charlie from tampering with data that Alice sends to Bob.
A cryptographic hash function is similar to a checksum. The main difference is that while a checksum is designed to detect accidental alterations in data, a cryptographic hash function is designed to detect deliberate alterations. When data is processed by a cryptographic hash function, a small string of bits, known as a hash, is generated. The slightest change to the message typically makes a large change in the resulting hash. A cryptographic hash function does not require a cryptographic key. Two hash functions often used with SSL are Message Digest 5 (MD5) and Secure Hash Algorithm (SHA). SHA was proposed by the US National Institute of Science and Technology (NIST).

Message Authentication Code

A message authentication code (MAC) is similar to a cryptographic hash, except that it is based on a secret key. When secret key information is included with the data that is processed by a cryptographic hash function, the resulting hash is known as an HMAC.
If Alice wants to be sure that Charlie does not tamper with her message to Bob, she can calculate an HMAC for her message and append the HMAC to her original message. She can then encrypt the message plus the HMAC using a secret key she shares with Bob. When Bob decrypts the message and calculates the HMAC, he will be able to tell if the message was modified in transit. With SSL, an HMAC is used with the transmission of secure data.

Digital Signatures

Once a cryptographic hash is created for a message, the hash is encrypted with the sender's private key. This encrypted hash is called a digital signature.

The SSL Process

Communication using SSL begins with an exchange of information between the client and the server. This exchange of information is called the SSL handshake.
The three main purposes of the SSL handshake are:

Negotiate the cipher suite

Authenticate identity (optional)

Establish information security by agreeing on encryption mechanisms

Negotiating the Cipher Suite

The SSL session begins with a negotiation between the client and the server as to which cipher suite they will use. A cipher suite is a set of cryptographic algorithms and key sizes that a computer can use to encrypt data. The cipher suite includes information about available public key exchange algorithms, secret key encryption algorithms, and cryptographic hash functions. The client tells the server which cipher suites it has available, and the server chooses the best mutually acceptable cipher suite.

Authenticating the Server

In SSL, the authentication step is optional, but in the example of an e-commerce transaction over the Web, the client will generally want to authenticate the server. Authenticating the server allows the client to be sure that the server represents the entity that the client believes the server represents.
To prove that a server belongs to the organization that it claims to represent, the server presents its public key certificate to the client. If this certificate is valid, the client can be sure of the identity of the server.
The client and server exchange information that allows them to agree on the same secret key. For example, with RSA, the client uses the server's public key, obtained from the public key certificate, to encrypt the secret key information. The client sends the encrypted secret key information to the server. Only the server can decrypt this message since the server's private key is required for this decryption.

Sending the Encrypted Data

Both the client and the server now have access to the same secret key. With each message, they use the cryptographic hash function, chosen in the first step of this process, and shared secret information, to compute an HMAC that they append to the message. They then use the secret key and the secret key algorithm negotiated in the first step of this process to encrypt the secure data and the HMAC. The client and server can now communicate securely using their encrypted and hashed data.

The SSL Protocol

The previous section provides a high-level description of the SSL handshake, which is the exchange of information between the client and the server prior to sending the encrypted message. This section provides more detail.
The "SSL Messages" figure below shows the sequence of messages that are exchanged in the SSL handshake. Messages that are only sent in certain situations are noted as optional. Each of the SSL messages is described in the following figure:

The SSL messages are sent in the following order:

Client hello - The client sends the server information including the highest version of SSL it supports and a list of the cipher suites it supports. (TLS 1.0 is indicated as SSL 3.1.) The cipher suite information includes cryptographic algorithms and key sizes.

Server hello - The server chooses the highest version of SSL and the best cipher suite that both the client and server support and sends this information to the client.

Certificate - The server sends the client a certificate or a certificate chain. A certificate chain typically begins with the server's public key certificate and ends with the certificate authority's root certificate. This message is optional, but is used whenever server authentication is required.

Certificate request - If the server needs to authenticate the client, it sends the client a certificate request. In Internet applications, this message is rarely sent.

Server key exchange - The server sends the client a server key exchange message when the public key information sent in 3) above is not sufficient for key exchange.

Server hello done - The server tells the client that it is finished with its initial negotiation messages.

Certificate - If the server requests a certificate from the client in Message 4, the client sends its certificate chain, just as the server did in Message 3.

Note: Only a few Internet server applications ask for a certificate from the client.

Client key exchange - The client generates information used to create a key to use for symmetric encryption. For RSA, the client then encrypts this key information with the server's public key and sends it to the server.

Certificate verify - In internet applications, this message is rarely sent. Its purpose is to allow the server to complete the process of authenticating the client. When this message is used, the client sends information that it digitally signs using a cryptographic hash function. When the server decrypts this information with the client's public key, the server is able to authenticate the client.

Change cipher spec - The client sends a message telling the server to change to encrypted mode.

Finished - The client tells the server that it is ready for secure data communication to begin.

Change cipher spec - The server sends a message telling the client to change to encrypted mode.

Finished - The server tells the client that it is ready for secure data communication to begin. This is the end of the SSL handshake.

Encrypted data - The client and the server communicate using the symmetric encryption algorithm and the cryptographic hash function negotiated in Messages 1 and 2, and using the secret key that the client sent to the server in Message 8.

If the parameters generated during an SSL session are saved, these parameters can sometimes be re-used for future SSL sessions. Saving SSL session parameters allows encrypted communication to begin much more quickly.

SSL and TLS References

For a list of resources containing more information about SSL, see Secure Sockets Layer Documentation .

TCP/IP Protocol Stack With SSL
TCP/IP Layer	Protocol
Application Layer	HTTP, NNTP, Telnet, FTP, etc.
Secure Sockets Layer	SSL
Transport Layer	TCP
Internet Layer	IP

Key Classes

Relationship Between Classes

To communicate securely, both sides of the connection must be SSL-enabled. In the JSSE API, the endpoint class of the connection is the SSLSocket. In the diagram below, the major classes used to create SSLSockets are laid out in a logical ordering.

An SSLSocket is created either by an SSLSocketFactory or by an SSLServerSocket accepting an in-bound connection. (In turn, an SSLServerSocket is created by an SSLServerSocketFactory.) Both SSLSocketFactory and SSLServerSocketFactory objects are created by an SSLContext.

There are two ways to obtain and initialize an SSLContext:

The simplest is to call the static getDefault method on either the SSLSocketFactory or SSLServerSocketFactory class. These methods create a default SSLContext with a default KeyManager, TrustManager, and a secure random number generator. (A default KeyManagerFactory and TrustManagerFactory are used to create the KeyManager and TrustManager, respectively.) The key material used is found in the default keystore/truststore, as determined by system properties described in Customizing the Default Key and Trust Stores, Store Types, and Store Passwords.

The approach that gives the caller the most control over the behavior of the created context is to call the static method getInstance on the SSLContext class, then initialize the context by calling the instance's proper init method. One variant of the init method takes three arguments: an array of KeyManager objects, an array of TrustManager objects, and a SecureRandom random number generator. (SunJSSE currently only uses this variant of init.) The KeyManager and TrustManager objects are created by either implementing the appropriate interface(s) or using the KeyManagerFactory and TrustManagerFactory classes to generate implementations. The KeyManagerFactory and TrustManagerFactory can then each be initialized with key material contained in the KeyStore passed as an argument to the TrustManagerFactory/KeyManagerFactory init method. Finally, the getTrustManagers method (in TrustManagerFactory) and getKeyManagers method (in KeyManagerFactory) can be called to obtain the array of trust or key managers, one for each type of trust or key material.

Once an SSL connection is established, an SSLSession is created which contains various information, such as identities established, cipher suite used, etc. The SSLSession is then used to describe an ongoing relationship and state information between two entities. Each SSL connection involves one session at a time, but that session may be used on many connections between those entities, simultaneously or sequentially.

Core Classes and Interfaces

The core JSSE classes are part of the javax.net and javax.net.ssl packages.
SocketFactory and ServerSocketFactory Classes

The abstract javax.net.SocketFactory class is used to create sockets. It must be subclassed by other factories, which create particular subclasses of sockets and thus provide a general framework for the addition of public socket-level functionality. (See, for example, SSLSocketFactory.)
The javax.net.ServerSocketFactory class is analogous to the SocketFactory class, but is used specifically for creating server sockets.
Socket factories are a simple way to capture a variety of policies related to the sockets being constructed, producing such sockets in a way which does not require special configuration of the code which asks for the sockets:

Due to polymorphism of both factories and sockets, different kinds of sockets can be used by the same application code just by passing different kinds of factories.

Factories can themselves be customized with parameters used in socket construction. So for example, factories could be customized to return sockets with different networking timeouts or security parameters already configured.

The sockets returned to the application can be subclasses of java.net.Socket (or javax.net.ssl.SSLSocket), so that they can directly expose new APIs for features such as compression, security, record marking, statistics collection, or firewall tunneling.

SSLSocket and SSLServerSocket Classes

The javax.net.ssl.SSLSocket class is a subclass of the standard Java java.net.Socket class. It supports all of the standard socket methods and adds additional methods specific to secure sockets. Instances of this class encapsulate the SSLContext under which they were created. There are APIs to control the creation of secure socket sessions for a socket instance but trust and key management are not directly exposed.
The javax.net.ssl.SSLServerSocket class is analogous to the SSLSocket class, but is used specifically for creating server sockets.
Implementation Note: Due to the complexity of the SSL and TLS protocols, it is difficult to predict whether incoming bytes on a connection are handshake or application data, and how that data might affect the current connection state (even causing the process to block). In the Sun JSSE implementation, the available() method on the object obtained by SSLSocket.getInputStream() returns a count of the number of application data bytes successfully decrypted from the SSL connection but not yet read by the application.
Obtaining an SSLSocket

Instances of SSLSocket can be obtained in two ways. First, an SSLSocket can be created by an instance of SSLSocketFactory via one of the several createSocket methods on that class. The second way to obtain SSLSockets is through the accept method on the SSLServerSocket class.

SSLSocketFactory and SSLServerSocketFactory Classes

A javax.net.ssl.SSLSocketFactory acts as a factory for creating secure sockets. This class is an abstract subclass of javax.net.SocketFactory.
Secure socket factories encapsulate the details of creating and initially configuring secure sockets. This includes authentication keys, peer certificate validation, enabled cipher suites and the like.
The javax.net.ssl.SSLServerSocketFactory class is analogous to the SSLSocketFactory class, but is used specifically for creating server sockets.
Obtaining an SSLSocketFactory

There are three primary ways of obtaining an SSLSocketFactory:

Get the default factory by calling the SSLSocketFactory.getDefault static method.

Receive a factory as an API parameter. That is, code which needs to create sockets but which doesn't care about the details of how the sockets are configured can include a method with an SSLSocketFactory parameter that can be called by clients to specify which SSLSocketFactory to use when creating sockets. (For example, javax.net.ssl.HttpsURLConnection.)

Construct a new factory with specifically configured behavior.

The default factory is typically configured to support server authentication only so that sockets created by the default factory do not leak any more information about the client than a normal TCP socket would.
Many classes which create and use sockets do not need to know the details of socket creation behavior. Creating sockets through a socket factory passed in as a parameter is a good way of isolating the details of socket configuration, and increases the reusability of classes which create and use sockets.
You can create new socket factory instances either by implementing your own socket factory subclass or by using another class which acts as a factory for socket factories. One example of such a class is SSLContext, which is provided with the JSSE implementation as a provider-based configuration class.

SSLSession Interface

A javax.net.ssl.SSLSession represents a security context negotiated between the two peers of an SSLSocket connection. Once a session has been arranged, it can be shared by future SSLSockets connected between the same two peers. The session contains the cipher suite which will be used for communications over a secure socket as well as a non-authoritative hint as to the network address of the remote peer, and management information such as the time of creation and last use. A session also contains a shared master secret negotiated between the peers that is used to create cryptographic keys for encrypting and guaranteeing the integrity of the communications over an SSLSocket. The value of this master secret is known only to the underlying secure socket implementation and is not exposed through the SSLSession API.

HttpsURLConnection Class

The https protocol is similar to http, but https first establishes a secure channel via SSL/TLS sockets before requesting/receiving data. javax.net.ssl.HttpsURLConnection extends the java.net.HttpsURLConnection class, and adds support for https-specific features. See the java.net.URL, java.net.URLConnection, and java.net.HttpURLConnection classes for more information about how http URLs are constructed and used.
Upon obtaining a HttpsURLConnection, you can configure a number of http/https parameters before actually initiating the network connection via the method URLConnection.connect. Of particular interest are:

Setting the Assigned SSLSocketFactory
Setting the Assigned HostnameVerifier

Setting the Assigned SSLSocketFactory

In some situations, it is desirable to specify the SSLSocketFactory that an HttpsURLConnection instance uses. For example, you may wish to tunnel through a proxy type that isn't supported by the default implementation. The new SSLSocketFactory could return sockets that have already performed all necessary tunneling, thus allowing HttpsURLConnection to use additional proxies.
The HttpsURLConnection class has a default SSLSocketFactory which is assigned when the class is loaded. (In particular it is the factory returned by the method SSLSocketFactory.getDefault.) Future instances of HttpsURLConnection will inherit the current default SSLSocketFactory until a new default SSLSocketFactory is assigned to the class via the static method HttpsURLConnection.setDefaultSSLSocketFactory. Once an instance of HttpsURLConnection has been created, the inherited SSLSocketFactory on this instance can be overriden with a call to the setSSLSocketFactory method.
Note that changing the default static SSLSocketFactory has no effect on existing instances of HttpsURLConnections, a call to the setSSLSocketFactory method is necessary to change the existing instance.
One can obtain the per-instance or per-class SSLSocketFactory by making a call to the getSSLSocketFactory/getDefaultSSLSocketFactory methods, respectively.

Setting the Assigned HostnameVerifier

If the hostname of the URL does not match the hostname in the credentials received as part of the SSL/TLS handshake, it's possible that URL spoofing has occured. If the implementation cannot determine a hostname match with reasonable certainty, the SSL implementation will perform a callback to the instance's assigned HostnameVerifier for futher checking. The hostname verifier can perform whatever steps are necessary to make the determination, such as performing alternate hostname pattern matching or perhaps popping up an interactive dialog box. An unsuccessful verification will close the connection. (See RFC 2818 for more information regarding hostname verification.)
The setHostnameVerifier/setDefaultHostnameVerifier methods operate in a similar manner to the setSSLSocketFactory/setDefaultSSLSocketFactory methods, in that there are HostnameVerifiers assigned on a per-instance and per-class basis, and the current values can be obtained by a call to the getHostnameVerifier/getDefaultHostnameVerifier methods.

Support Classes and Interfaces
The classes and interfaces in this section are provided to support the creation and initialization of SSLContext objects, which are used to create SSLSocketFactory and SSLServerSocketFactory objects. The support classes and interfaces are part of the javax.net.ssl package.
Three of the classes described in this section ( SSLContext, KeyManagerFactory, and TrustManagerFactory) are engine classes. An engine class is an API class for specific algorithms (or protocols, in the case of SSLContext), for which implementations may be provided in one or more Cryptographic Service Provider (provider) packages. For more information on providers and engine classes, see the "Design Principles" and "Concepts" sections of the Java^TM Cryptography Architecture API Specification & Reference.
The SunJSSE provider that comes standard with JSSE provides SSLContext, KeyManagerFactory, and TrustManagerFactory implementations, as well as implementations for engine classes in the standard Java security (java.security) API. The implementations supplied by SunJSSE are:
Engine Class        Algorithm or 
Implemented           Protocol

KeyFactory            "RSA"

KeyPairGenerator      "RSA"

KeyStore              "PKCS12"

Signature             "MD2withRSA"
Signature             "MD5withRSA"
Signature             "SHA1withRSA"

KeyManagerFactory     "SunX509"
TrustManagerFactory   "SunX509", "SunPKIX"

SSLContext            "SSL"
SSLContext            "SSLv3"
SSLContext            "TLS"
SSLContext            "TLSv1"
SSLContext Class
javax.net.ssl.SSLContext is an engine class for an implementation of a secure socket protocol. An instance of this class acts as a factory for SSL socket factories. An SSLContext holds all of the state information shared across all sockets created under that context. For example, session state is associated with the SSLContext when it is negotiated through the handshake protocol by sockets created by socket factories provided by the context. These cached sessions can be reused and shared by other sockets created under the same context.
Each instance is configured through its init method with the keys, certificate chains, and trusted root CA certificates that it needs to perform authentication. This configuration is provided in the form of key and trust managers. These managers provide support for the authentication and key agreement aspects of the cipher suites supported by the context.
Currently, only X.509-based managers are supported.
Creating an SSLContext Object
Like other JCA provider-based "engine" classes, SSLContext objects are created using the getInstance factory methods of the SSLContext class. These static methods each return an instance that implements at least the requested secure socket protocol. The returned instance may implement other protocols too. For example, getInstance("SSLv3") may return a instance which implements SSLv3 and TLSv1. The getSupportedProtocols method returns a list of supported protocols when an SSLSocket or SSLServerSocket is created from a socket factory obtained from this context. You can control which protocols are actually enabled for an SSL connection by using the method setEnabledProtocols(String[] protocols). (Refer to the API documention for this method in the SSLSocket and the SSLServerSocket classes for more information.)
Note: An SSLContext object is automatically created, initialized, and statically assigned to the SSLSocketFactory class when you call SSLSocketFactory.getDefault. Therefore, you don't have to directly create and initialize an SSLContext object (unless you want to override the default behavior).
To create an SSLContext object by calling a getInstance factory method, you must specify the protocol name. You may also specify which provider you want to supply the implementation of the requested protocol:
public static SSLContext getInstance(String protocol);

public static SSLContext getInstance(String protocol,
                                     String provider);

public static SSLContext getInstance(String protocol,
                                     Provider provider);
If just a protocol name is specified, the system will determine if there is an implementation of the requested protocol available in the environment, and if there is more than one, if there is a preferred one.
If both a protocol name and a provider are specified, the system will determine if there is an implementation of the requested protocol in the provider requested, and throw an exception if there is not.
A protocol is a string (such as "SSL") that describes the secure socket protocol desired. Common protocol names for SSLContext objects are defined in Appendix A.
Here is an example of obtaining an SSLContext:
SSLContext sc = SSLContext.getInstance("SSL");
A newly-created SSLContext should be initialized by calling the init method:
public void init(KeyManager[] km, TrustManager[] tm,
                   SecureRandom random);
If the KeyManager[] paramater is null, then an empty KeyManager will be defined for this context. If the TrustManager[] parameter is null, the installed security providers will be searched for the highest-priority implementation of the TrustManagerFactory, from which an appropriate TrustManager will be obtained. Likewise, the SecureRandom parameter may be null, in which case a default implementation will be used.
If the internal default context is used, (e.g. a SSLContext is created in the internals of JSSE), a default KeyManager and a TrustManager are created. The default SecureRandom implementation is also chosen.
TrustManager Class

The primary responsibility of the TrustManager is to determine whether the presented authentication credentials should be trusted. If the credentials are not trusted, the connection will be terminated. To authenticate the remote identity of a secure socket peer, you need to initialize an SSLContext object with one or more TrustManagers. You need to pass one TrustManager for each authentication mechanism that is supported. If null is passed into the SSLContext initialization, a trust manager will be created for you. Typically, there is a single trust manager that supports authentication based on X.509 public key certificates. Some secure socket implementations may also support authentication based on shared secret keys, Kerberos, or other mechanisms.

TrustManagerFactory Class
The javax.net.ssl.TrustManagerFactory is an engine class for a provider-based service that acts as a factory for one or more types of TrustManager objects. The SunJSSE provider implements a factory which can return a basic X.509 trust manager. Because it is provider-based, additional factories can be implemented and configured that provide additional or alternate trust managers that provide more sophisticated services or that implement installation-specific authentication policies.
In the 1.4.2 release of the Java 2 platform, a CertPath-based X.509 trust manager called "SunPKIX" TrustManagerFactory class was added. SunPKIX is available in addition to the previously available simple X.509 trust manager. For compatibility, it is not active by default. It can be enabled by changing the ssl.TrustManagerFactory.algorithm property in the java.security file from "SunX509" to "SunPKIX". Alternatively, it can be accessed programmatically by calling TrustManagerFactory.getInstance("SunPKIX"). The same "SunX509" TrustManagerFactory algorithm for cacerts (javax.net.ssl.trustStore/jssecacerts/cacerts) also initializes the SunPKIX algorithm.
Note: The algorithm name "SunPKIX" is preliminary and may change after standardization in a future release.
The PKIX trust manager uses the CertPath PKIX implementation from an installed security provider. In the currect release, you cannot specify the PKIXParameters to be used for validation; a suitable API will be added in a future release. Currently, the default PKIXParameters are used with the exception that revocation checking is disabled. It can be enabled by setting the system property com.sun.net.ssl.checkRevocation to true. Note that this setting requires that the CertPath implementation can locate revocation information by itself. The PKIX implementation in the SUN provider can do this in many cases but requires that the system property com.sun.security.enableCRLDP be set to true. For details see the Java^TM Certification Path API Programmer's Guide.
Creating a TrustManagerFactory
You create an instance of this class in a similar manner to SSLContext, except for passing an algorithm name string instead of a protocol name to the getInstance method:
public static TrustManagerFactory
                  getInstance(String algorithm);

public static TrustManagerFactory
                  getInstance(String algorithm,
                              String provider);

public static TrustManagerFactory
                  getInstance(String algorithm,
                              Provider provider);
A sample algorithm name string is:
"SunX509"

A sample call is the following:
TrustManagerFactory tmf =
    TrustManagerFactory.getInstance("SunX509", "SunJSSE");
The above call will create an instance of the SunJSSE provider's default trust manager factory. This factory can then be used to create trust managers which provide basic X.509-based certification path validity checking.
When initializing a SSLContext, you can use trust managers created from a trust manager factory, or you can write your own trust manager, perhaps using the CertPath API. (See the Java^TM Certification Path API Programmer's Guide for details.) You don't need to use a trust manager factory at all if you implement a trust manager using the X509TrustManager interface.
A newly-created factory should be initialized by calling one of the init methods:
public void init(KeyStore ks);
public void init(ManagerFactoryParameters spec);
You should call whichever init method is appropriate for the TrustManagerFactory you are using. (Ask the provider vendor.)
For many factories, such as the default "SunX509" TrustManagerFactory from the SunJSSE provider, the KeyStore is the only information required in order to initialize the TrustManagerFactory and thus the first init method is the appropriate one to call. The TrustManagerFactory will query the KeyStore for information on which remote certificates should be trusted during authorization checks.
In some cases, initialization parameters other than a KeyStore may be needed by a provider. Users of that particular provider are expected to pass an implementation of the appropriate ManagerFactoryParameters as defined by the provider. The provider can then call the specified methods in the ManagerFactoryParameters implementation to obtain the needed information.
For example, suppose the TrustManagerFactory provider requires initialization parameters B, R, and S from any application that wishes to use that provider. Like all providers that require initialization parameters other than a KeyStore, the provider will require that the application provide an instance of a class that implements a particular ManagerFactoryParameters sub-interface. In our example, suppose the provider requires that the calling application implement and create an instance of MyTrustManagerFactoryParams and pass it to the second init. Here is what MyTrustManagerFactoryParams may look like:
public interface MyTrustManagerFactoryParams extends 
       ManagerFactoryParameters {
    public boolean getBValue();
    public float getRValue();
    public String getSValue():
}
Some trustmanagers are capable of making trust decisions without having to be explicitly initialized with a KeyStore object or any other parameters. For example, they may access trust material from a local directory service via LDAP, may use a remote online certificate status checking server, or may access default trust material from a standard local location.
X509TrustManager Interface
The javax.net.ssl.X509TrustManager interface extends the general TrustManager interface. This interface must be implemented by a trust manager when using X.509-based authentication.
In order to support X.509 authentication of remote socket peers through JSSE, an instance of this interface must be passed to the init method of an SSLContext object.
Creating an X509TrustManager
You can either implement this interface directly yourself or obtain one from a provider-based TrustManagerFactory (such as that supplied by the SunJSSE provider). You could also implement your own that delegates to a factory-generated trust manager. For example, you might do this in order to filter the resulting trust decisions and query an end-user through a graphical user interface.
Note: If a null KeyStore parameter is passed to the SunJSSE default "SunX509" TrustManagerFactory, the factory uses the following steps to try to find trust material:
If the system property:
javax.net.ssl.trustStore
is defined, then the TrustManagerFactory attempts to find a file using the filename specified by that system property, and uses that file for the KeyStore. If the javax.net.ssl.trustStorePassword system property is also defined, its value is used to check the integrity of the data in the truststore before opening it.
If javax.net.ssl.trustStore is defined but the specified file does not exist, then a default TrustManager using an empty keystore is created.
If the javax.net.ssl.trustStore system property was not specified, then if the file
<java-home>/lib/security/jssecacerts
exists, that file is used. (See The Installation Directory <java-home> for information about what <java-home> refers to.) Otherwise,
If the file
<java-home>/lib/security/cacerts
exists, that file is used.
(If none of these files exists, that may be okay because there are SSL cipher suites which are anonymous, that is, which don't do any authentication and thus don't need a truststore.)
The factory looks for a file specified via the security property javax.net.ssl.trustStore or for the jssecacerts file before checking for a cacerts file so that you can provide a JSSE-specific set of trusted root certificates separate from ones that might be present in cacerts for code-signing purposes.
Creating Your Own X509TrustManager
If the default X509TrustManager behavior isn't suitable for your situation, you can create your own X509TrustManager by either creating and registering your own TrustManagerFactory or by implementing the X509TrustManager interface directly.
The following MyX509TrustManager class enhances the default SunJSSE X509 TrustManager behavior by providing alternative authentication logic when the default SunJSSE X509 TrustManager fails.
class MyX509TrustManager implements X509TrustManager {

    X509TrustManager sunX509TrustManager;

    MyX509TrustManager() {
        // create sunX509TrustManager
        //
        // for example:
        //     Create/load a keystore
        //     Get instance of a "SunX509" TrustManagerFactory "tmf"
        //     init the TrustManagerFactory with the keystore

        sunX509TrustManager = tmf.getTrustManagers()[0]
    }

    ... // checkClientTrusted method omitted

    public void checkServerTrusted(X509Certificate[] chain,
                                   String authType)
                                   throws CertificateException) {
        try {
            sunX509TrustManager.checkServerTrusted(chain, authType);
        } catch (CertificateException excep) {
            // do any special handling, such as popping up
            // dialog boxes, prompting the user, etc.
        }
    }

    public X509Certificate[] getAcceptedIssuers() {
        return sunJSSETrustManager.getAcceptedIssuers();
    }
}
Once you have created such a trust manager, assign it to an SSLContext via the init method. Future SocketFactories created from this SSLContext will use your new TrustManager when making trust decisions.
TrustManager[] myTM = new TrustManager [] { 
                             new MyX509TrustManager() };
SSLContext ctx = SSLContext.getInstance("TLS");
ctx.init(null, myTM, null);
Updating the keyStore Dynamically

You can enhance MyX509TrustManager to handle dynamic keystore updates. When a checkClientTrusted or checkServerTrusted test fails and does not establish a trusted certificate chain, you can add the required trusted certificate to the keystore. You need to create a new sunX509TrustManager from the TrustManagerFactory initialized with the updated keystore. When you establish a new connection (using the previously initialized SSLContext), the newly added certificate will be called to make the trust decisions.
KeyManager Class

The primary responsibility of the KeyManager is to select the authentication credentials that will eventually be sent to the remote host. To authenticate yourself (a local secure socket peer) to a remote secure socket peer, you need to initialize an SSLContext object with one or more KeyManagers. You need to pass one KeyManager for each different authentication mechanism that will be supported. If null is passed into the SSLContext initialization, an empty KeyManager will be created. If the internal default context is used, a default KeyManager is created. Typically, there is a single key manager that supports authentication based on X.509 public key certificates. Some secure socket implementations may also support authentication based on shared secret keys, Kerberos, or other mechanisms.

KeyManagerFactory Class
javax.net.ssl.KeyManagerFactory is an engine class for a provider-based service that acts as a factory for one or more types of KeyManager objects. The SunJSSE provider implements a factory which can return a basic X.509 key manager. Because it is provider-based, additional factories can be implemented and configured to provide additional or alternate key managers.
Creating a KeyManagerFactory
You create an instance of this class in a similar manner to SSLContext, except for passing an algorithm name string instead of a protocol name to the getInstance method:
public static KeyManagerFactory
                  getInstance(String algorithm);

public static KeyManagerFactory
                  getInstance(String algorithm,
                              String provider);

public static KeyManagerFactory
                  getInstance(String algorithm,
                              Provider provider);
A sample algorithm name string is:
"SunX509"

A sample call is the following:
KeyManagerFactory kmf =
    KeyManagerFactory.getInstance("SunX509", "SunJSSE");
The above call will create an instance of the SunJSSE provider's default key manager factory, which provides basic X.509-based authentication keys.
A newly-created factory should be initialized by calling one of the init methods:
public void init(KeyStore ks, char[] password);
public void init(ManagerFactoryParameters spec);
You should call whichever init method is appropriate for the KeyManagerFactory you are using. (Ask the provider vendor.)
For many factories, such as the default "SunX509" KeyManagerFactory from the SunJSSE provider, the KeyStore and password are the only information required in order to initialize the KeyManagerFactory and thus the first init method is the appropriate one to call. The KeyManagerFactory will query the KeyStore for information on which private key and matching public key certificates should be used for authenticating to a remote socket peer. The password parameter specifies the password that will be used with the methods for accessing keys from the KeyStore. All keys in the KeyStore must be protected by the same password.
In some cases, initialization parameters other than a KeyStore and password may be needed by a provider. Users of that particular provider are expected to pass an implementation of the appropriate ManagerFactoryParameters as defined by the provider. The provider can then call the specified methods in the ManagerFactoryParameters implementation to obtain the needed information.
Some factories are capable of providing access to authentication material without having to be initialized with a KeyStore object or any other parameters. For example, they may access key material as part of a login mechanism such as one based on JAAS, the Java Authentication and Authorization Service.
As indicated above, the SunJSSE provider supports a "SunX509" factory that must be initialized with a KeyStore parameter.
X509KeyManager Interface
The javax.net.ssl.X509KeyManager interface extends the general KeyManager interface. It must be implemented by a key manager for X.509-based authentication. In order to support X.509 authentication to remote socket peers through JSSE, an instance of this interface must be passed to the init method of an SSLContext object.
Creating an X509KeyManager
You can either implement this interface directly yourself or obtain one from a provider-based KeyManagerFactory (such as that supplied by the SunJSSE provider). You could also implement your own that delegates to a factory-generated key manager. For example, you might do this in order to filter the resulting keys and query an end-user through a graphical user interface.
Note: If no KeyStore parameter is passed to the SunJSSE default "SunX509" KeyManagerFactory, the factory tries to find key material by consulting the system properties
javax.net.ssl.keyStore
javax.net.ssl.keyStorePassword
If these properties specify a file with an appropriate password, the factory uses this file for the KeyStore. If that file does not exist, then a default KeyManager using an empty keystore is created.
Generally, the process acting as the server in the handshake will need a keystore for its KeyManager in order to obtain credentials for authentication to the client. However, if one of the anonymous cipher suites is selected, the server's KeyManager keystore is not necessary. And, unless the server requires client authentication, the process acting as the client will not need a KeyManager keystore. Thus, in these situations it may be okay if there is no javax.net.ssl.keyStore system property value defined.
Creating Your Own X509KeyManager

If the default X509KeyManager behavior isn't suitable for your situation, you can create your own X509KeyManager in a way similiar to that shown in Creating Your Own X509TrustManager.
Relationships between TrustManagers and KeyManagers

Historically there has been confusion regarding the jobs of TrustManagers and KeyManagers. In summary, here are the primary responsibilities of each manager type:

Type Function

TrustManager Determines whether the remote authentication credentials (and thus the connection) should be trusted.

KeyManager Determines which authentication credentials to send to the remote host.

Secondary Support Classes and Interfaces
These classes are provided as part of the JSSE API to support the creation, use, and management of secure sockets. They are less likely to be used by secure socket applications than are the core and support classes. The secondary support classes and interfaces are part of the javax.net.ssl and javax.security.cert packages.
SSLSessionContext Interface

A javax.net.ssl.SSLSessionContext is a grouping of SSLSessions associated with a single entity. For example, it could be associated with a server or client that participates in many sessions concurrently. The methods on this interface enable the enumeration of all sessions in a context and allow lookup of specific sessions via their session ids.
An SSLSessionContext may optionally be obtained from an SSLSession by calling the SSLSession getSessionContext method. The context may be unavailable in some environments, in which case the getSessionContext method returns null.

SSLSessionBindingListener Interface

javax.net.ssl.SSLSessionBindingListener is an interface implemented by objects which want to be notified when they are being bound or unbound from an SSLSession.

SSLSessionBindingEvent Class

A javax.net.ssl.SSLSessionBindingEvent is the event communicated to an SSLSessionBindingListener when it is bound or unbound from an SSLSession.

HandShakeCompletedListener Interface

javax.net.ssl.HandShakeCompletedListener is an interface implemented by any class which wants to receive notification of the completion of an SSL protocol handshake on a given SSLSocket connection.

HandShakeCompletedEvent Class

A javax.net.ssl.HandShakeCompletedEvent is the event communicated to a HandShakeCompletedListener upon completion of an SSL protocol handshake on a given SSLSocket connection.

HostnameVerifier Interface
If the SSL/TLS implementation's standard hostname verification logic fails, the implementation will call the verify method of the class which implements this interface and is assigned to this HttpsURLConnection instance. If the callback class can determine that the hostname is acceptable given the parameters, it should report that the connection should be allowed. An unacceptable response will cause the connection to be terminated.
For example:
public class MyHostnameVerifier implements HostnameVerifier {

    public boolean verify(String hostname, SSLSession session) {
        // pop up an interactive dialog box
        // or insert additional matching logic
        if (good_address) {
            return true;
        } else {
            return false;
        }
    }
}

//...deleted...

HttpsURLConnection urlc = (HttpsURLConnection)
  (new URL("https://www.sun.com/")).openConnection();
urlc.setHostnameVerifier(new MyHostnameVerifier());
See HttpsURLConnection Class for more information on how to assign the HostnameVerifier to the HttpsURLConnection.
X509Certificate Class

Many secure socket protocols perform authentication using public key certificates, also called X.509 certificates. This is the default authentication mechanism for the SSL and TLS protocols.
The java.security.cert.X509Certificate abstract class provides a standard way to access the attributes of X.509 certificates.
Note: The javax.security.cert.X509Certificate class is supported only for backward compatibility with previous (1.0.x and 1.1.x) versions of JSSE. New applications should use java.security.cert.X509Certificate, not javax.security.cert.X509Certificate.
Previous (JSSE 1.0.x) Implementation Classes and Interfaces

In previous (1.0.x) versions of JSSE, there was a reference implementation whose classes and interfaces were provided in the com.sun.net.ssl package.
Now JSSE has been integrated into the J2SDK, v 1.4. The classes formerly in com.sun.net.ssl have been promoted to the javax.net.ssl package and are now a part of the standard JSSE API.
For compatibility purposes the com.sun.net.ssl classes and interfaces still exist, but have been deprecated. Applications written using them can run in the J2SDK, v 1.4 without being recompiled. This may change in a future release; these classes/interfaces may be removed. Thus, all new applications should be written using the javax classes/interfaces.
For now, applications written using the com.sun.net.ssl API can utilize either JSSE 1.0.2 providers (ones using com.sun.net.ssl) or JSSE providers written for the J2SDK, v 1.4 (ones using the javax API). However, applications written using the JSSE API in the J2SDK, v 1.4 can only utilize JSSE providers written for the J2SDK, v 1.4. This new release contains some new functionality and attempting to access such functionality on a provider that doesn't supply it wouldn't work. SunJSSE, provided with the J2SDK from Sun Microsystems, is a provider written using the javax API.
You can still obtain a com.sun.net.ssl.HttpsURLConnection if you update the URL search path by setting the java.protocol.handler.pkgs System property as you did when using JSSE 1.0.2. For more information, see Code Using HttpsURLConnection Class... in the Troubleshooting section.

Type	Function
`TrustManager`	Determines whether the remote authentication credentials (and thus the connection) should be trusted.
`KeyManager`	Determines which authentication credentials to send to the remote host.

Customizing JSSE

The Installation Directory <java-home>
The term <java-home> is used throughout this document to refer to the directory where the Java 2 Runtime Environment (JRE) is installed. It is determined based on whether you are running JSSE on a JRE with or without the Java^TM 2 SDK installed. Java 2 SDK includes the JRE, but it is located in a different level in the file hierarchy.
The following are some examples of which directories <java-home> refers to:
On Solaris, if the Java 2 SDK is installed in /home/user1/j2sdk1.4.0, then <java-home> is
/home/user1/j2sdk1.4.0/jre
On Solaris, if JRE is installed in /home/user1/j2re1.4.0 and the Java 2 SDK is not installed, then <java-home> is
/home/user1/j2re1.4.0
On Microsoft Windows platforms, if the Java 2 SDK is installed in C:\j2sdk1.4.0, then <java-home> is
C:\j2sdk1.4.0\jre
On Microsoft Windows platforms, if the JRE is installed in C:\j2re1.4.0 and the Java 2 SDK is not installed, then <java-home> is
C:\j2re1.4.0
Customization

JSSE includes an implementation that all users can utilize. If desired, it is also possible to customize a number of aspects of JSSE, plugging in different implementations or specifying the default keystore, etc. The table below summarizes which aspects can be customized, what the defaults are, and which mechanisms are used to provide customization. The first column of the table provides links to more detailed descriptions of each designated aspect and how to customize it.
Some of the customizations are done by setting system property or security property values. Sections following the table explain how to set such property values.

IMPORTANT NOTE: Many of the properties shown in this table are currently utilized by the JSSE implementation, but there is no guarantee that they will continue to have the same names and types (system or security) or even that they will exist at all in future releases. All such properties are flagged with an "*". They are documented here for your convenience for use with the JSSE implementation.

JSSE Customization

Customizable Item

Default

How To Customize

X509Certificate implementation
X509Certificate implementation from Sun Microsystems

cert.provider.x509v1 security property

HTTPS protocol implementation
Implementation from Sun Microsystems

java.protocol.handler.pkgs system property

provider implementation
SunJSSE

A security.provider.n= line in security properties file. See description.

default SSLSocketFactory implementation
SSLSocketFactory implementation from Sun Microsystems.

** ssl.SocketFactory.provider security property

default SSLServerSocketFactory implementation
SSLServerSocketFactory implementation from Sun Microsystems.

** ssl.ServerSocketFactory.provider security property

default keystore
None.

* javax.net.ssl.keyStore system property

default keystore type
KeyStore.getDefaultType()

* javax.net.ssl.keyStoreType system property

default keystore password
None.

* javax.net.ssl.keyStorePassword system property

default truststore
jssecacerts, if it exists. Otherwise, cacerts

* javax.net.ssl.trustStore system property

default truststore type
KeyStore.getDefaultType()

* javax.net.ssl.trustStoreType system property

default truststore password
None.

* javax.net.ssl.trustStorePassword system property

default key manager factory algorithm name
"SunX509"
ssl.KeyManagerFactory.algorithm security property

default trust manager factory algorithm name
"SunX509"
ssl.TrustManagerFactory.algorithm security property

default proxy host
None.
* https.proxyHost system property

default proxy port
80
* https.proxyPort system property

default ciphersuites
Determined by the socket factory
* https.cipherSuites system property. This contains a comma-separated list of cipher suite names specifying which cipher suites to enable for use on this HttpsURLConnection. See the SSLSocket setEnabledCipherSuites(String[]) method.

default handshaking protocols
Determined by the socket factory
* https.protocols system property. This contains a comma-separated list of protocol suite names specifying which protocol suites to enable on this HttpsURLConnection. See the SSLSocket setEnabledProtocols(String[]) method.

<

Customizable Item	Default	How To Customize
X509Certificate implementation	X509Certificate implementation from Sun Microsystems	cert.provider.x509v1 security property
HTTPS protocol implementation	Implementation from Sun Microsystems	java.protocol.handler.pkgs system property
provider implementation	SunJSSE	A security.provider.n= line in security properties file. See description.
default SSLSocketFactory implementation	SSLSocketFactory implementation from Sun Microsystems.	** ssl.SocketFactory.provider security property
default SSLServerSocketFactory implementation	SSLServerSocketFactory implementation from Sun Microsystems.	** ssl.ServerSocketFactory.provider security property
default keystore	None.	* javax.net.ssl.keyStore system property
default keystore type	KeyStore.getDefaultType()	* javax.net.ssl.keyStoreType system property
default keystore password	None.	* javax.net.ssl.keyStorePassword system property
default truststore	jssecacerts, if it exists. Otherwise, cacerts	* javax.net.ssl.trustStore system property
default truststore type	KeyStore.getDefaultType()	* javax.net.ssl.trustStoreType system property
default truststore password	None.	* javax.net.ssl.trustStorePassword system property
default key manager factory algorithm name	"SunX509"	ssl.KeyManagerFactory.algorithm security property
default trust manager factory algorithm name	"SunX509"	ssl.TrustManagerFactory.algorithm security property
default proxy host	None.	* https.proxyHost system property
default proxy port	80	* https.proxyPort system property
default ciphersuites	Determined by the socket factory	* https.cipherSuites system property. This contains a comma-separated list of cipher suite names specifying which cipher suites to enable for use on this `HttpsURLConnection`. See the SSLSocket setEnabledCipherSuites(String[]) method.
default handshaking protocols	Determined by the socket factory	* https.protocols system property. This contains a comma-separated list of protocol suite names specifying which protocol suites to enable on this `HttpsURLConnection`. See the SSLSocket setEnabledProtocols(String[]) method.
<

JavaTM Secure Socket Extension (JSSE)

Reference Guide

for the JavaTM 2 SDK, Standard Edition, v 1.4.2

Introduction

Features and Benefits

Cryptographic Functionality Available With JSSE

JSSE Standard API

SunJSSE Provider

What's New

What's New in JSSE in the J2SDK, v 1.4.2

What's New in JSSE in the J2SDK, v 1.4

JSSE Is Now in J2SDK

javax.security.cert Should Not Be Used

SunJSSE Provider Can Use JCE Providers for Encryption

Classes Formerly in com.sun.net.ssl Are Now in javax.net.ssl

New Methods and Interfaces

Changed Classes and Methods

Documentation Improvements

Related Documentation

Java Secure Socket Extension Documentation

Java 2 Platform Security Documentation

Export Issues Related to Cryptography

Cryptography Documentation

Secure Sockets Layer Documentation

Terms and Definitions

Authentication

Cipher Suite

Certificate

Cryptographic Hash Function

Cryptographic Service Provider

Digital Signature

Encryption and Decryption

Handshake Protocol

Key Agreement

Key Managers and Trust Managers

Keystores and Truststores

Message Authentication Code

Public Key Cryptography

Record Protocol

Secret Key Cryptography

Session

Trust Managers

Truststore

Secure Sockets Layer (SSL) Protocol Overview

TCP/IP Protocol Stack With SSL

Why Use SSL?

How SSL Works

Cryptographic Processes

Secret Key Cryptography

Public Key Cryptography

A Comparison Between Secret Key and Public Key Cryptography

Public Key Certificates

Cryptographic Hash Functions

Message Authentication Code

Digital Signatures

The SSL Process

Negotiating the Cipher Suite

Authenticating the Server

Sending the Encrypted Data

The SSL Protocol

SSL and TLS References

Key Classes

Relationship Between Classes

Core Classes and Interfaces

SocketFactory and ServerSocketFactory Classes

SSLSocket and SSLServerSocket Classes

Obtaining an SSLSocket

SSLSocketFactory and SSLServerSocketFactory Classes

Obtaining an SSLSocketFactory

SSLSession Interface

HttpsURLConnection Class

Setting the Assigned SSLSocketFactory

Setting the Assigned HostnameVerifier

Support Classes and Interfaces

SSLContext Class

Creating an SSLContext Object

TrustManager Class

TrustManagerFactory Class

Creating a TrustManagerFactory

X509TrustManager Interface

Java^TM Secure Socket Extension (JSSE)

for the Java^TM 2 SDK, Standard Edition, v 1.4.2

`SunJSSE` Provider

`javax.security.cert` Should Not Be Used

`SocketFactory` and `ServerSocketFactory` Classes

`SSLSocket` and `SSLServerSocket` Classes

Obtaining an `SSLSocket`

`SSLSocketFactory` and `SSLServerSocketFactory` Classes

Obtaining an `SSLSocketFactory`

`SSLSession` Interface

`HttpsURLConnection` Class

Setting the Assigned `SSLSocketFactory`

Setting the Assigned `HostnameVerifier`

`SSLContext` Class

Creating an `SSLContext` Object

`TrustManager` Class

`TrustManagerFactory` Class

Creating a `TrustManagerFactory`

`X509TrustManager` Interface

Creating an `X509TrustManager`

Creating Your Own `X509TrustManager`

Updating the `keyStore` Dynamically

`KeyManager` Class

`KeyManagerFactory` Class

Creating a `KeyManagerFactory`

`X509KeyManager` Interface

Creating an `X509KeyManager`

Creating Your Own `X509KeyManager`

Relationships between `TrustManager`s and `KeyManager`s

`SSLSessionContext` Interface

`SSLSessionBindingListener` Interface

`SSLSessionBindingEvent` Class

`HandShakeCompletedListener` Interface

`HandShakeCompletedEvent` Class

`HostnameVerifier` Interface

`X509Certificate` Class