[SANTUARIO-227] impossible to subclass XMLCipher

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Won't Fix
• Component/s: Java
• Security Level: Public (Public issues, viewable by everyone)
• Environment: Operating System: Windows NT; Platform: PC
• Bugzilla Id: 49465
• Assignee: Unassigned
• Reporter: Clement Pellerin
• Created: 18/Jun/10 18:17
• Updated: 28/Mar/12 09:38
• Resolved: 28/Mar/12 09:37

Description

Created an attachment (id=25614)
source code patch and new junit

The constructor of XMLCipher is private which makes it impossible to subclass XMLCipher. Furthermore, much of the work to construct the XMLCipher instance is located in the getInstance() or getProviderInstance() methods. That would force a subclass to duplicate that code once again.

The goal of this effort is to experiment with per KeyInfo KeyResolvers to resolve the Key Encryption Key dynamically based on the EncryptedKey/KeyInfo carried in the message. The junit in attachment shows how to achieve it through subclassing. This might not be the most obvious use of the API, but at least it proves that it can be done. It has the advantage that none of the API changes are controversial.

The solution involves:

• Making the XMLCipher constructor protected. Callers must still call one of the getInstance() or getProviderInstance() methods.
• pushing all the construction code in getInstance() and getProviderInstance() into the real constructor.
• relaxing the requirement that provider must not be null. Passing null for the provider in getProviderInstance() gives the same result as using the equivalent getInstance() method.
• Adding createKeyInfo() and createEncryptedKeyResolver() factory methods in XMLCipher.
• Changing XMLCipher to use the new factory methods when creating internal KeyInfo or EncryptedKeyResolver objects.
• Adding the method createXMLCipher() to EncryptedKeyResolver.
• Also added some test to @return keywords that were empty in XMLCipher

Issue Links

• is superceded by: SANTUARIO-305 No way to register internal key resolvers in DECRYPT_MODE