Monday, September 19, 2011

Specifying custom AlgorithmSuite policies in Apache CXF 2.4.3

When specifying a security binding via WS-SecurityPolicy, it is possible to define the algorithm suite via the "sp:AlgorithmSuite" policy. WS-SecurityPolicy defines a number of standard AlgorithmSuite policies, which control various security properties like the maximum and minimum Symmetric and Asymmetric key lengths, the encryption/signature/digest algorithms to use, etc. An example policy is given below. For this policy, the minimum symmetric key length is 256 bits, and the encryption algorithm is AES256:

        <sp:Basic256 />

There are certain scenarios where a user might want to use a non-standard AlgorithmSuite. For example, the minimum Asymmetric Key Length for all standard AlgorithmSuites is 1024 bits. This requires that the JDK has unrestricted security policies installed. If it is not possible to install unresticted security policies, a user might decide that using 512 bits RSA keys is sufficient (this is not recommended).

Apache CXF 2.4.3 provides support for specifying custom algorithm suites. A new interface is defined to create an AlgorithmSuite object given a policy, with a default implementation that supports the standard AlgorithmSuite policies. It is possible to create a new implementation of the AlgorithmSuiteLoader interface, and install it as a bus extension. For an example, there is a CXF system test that allows 512 bit asymmetric keys, with custom AlgorithmSuiteLoader and AlgorithmSuite implementations. The custom AlgorithmSuiteLoader implementation is spring-loaded, and registers itself as a bus extension.

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