WS-* Security Standards: Too Much Of A Good Thing?

WS-Security 1.1. Describes how XML Encryption and XML Signature can be applied to SOAP documents or messages. Supported by all vendors and used by all other WS-* standards involving security. The latest version, published in February 2006, will likely be the last, as future enhancements will be included in other standards.

WS-SecurityPolicy 1.2. Specifies who is allowed to access a service and how, and restricts the kinds of authentication methods allowed and/or the level of encryption required. It is a subset of WS-Policy, a more general way of expressing a service's capabilities and limitations. Developed by IBM and Microsoft, WS-SecurityPolicy was officially standardized in July 2007 and will eventually be supported by all vendors.

WS-SecureConversation 1.3. A means of implementing the policies expressed in WS-SecurityPolicy using WS-Security. The standard was ratified in March 2007, at which point IBM and Sun demonstrated implementations. Other vendors, including Actional, BEA Systems, Cisco, Computer Associates, Layer 7 Technologies, Oracle, Reactivity, RSA Security, and VeriSign, have also pledged support, though few customers are using it at present.

WS-Trust 1.3. Uses WS-Security to transfer security tokens, such as passwords, digital certificates and SAML assertions. Non-SOAP Web services have a partial equivalent in XKMS (XML Key Management Specification) and SAML.

WS-Federation 1.1. Uses the security tokens transferred in WS-Trust to authenticate to Web services, according to the service's rules as described in WS-SecurityPolicy. Not yet widely used, as SAML provides much of the same functionality. Its main advantage over SAML is Windows support and tight integration with the WS-* stack.