[SANTUARIO-616] ClassCastException regression in XMLCipher related to new AgreementMethod support

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Java 3.0.4, Java 4.0.2
• Fix Version/s: Java 3.0.5, Java 4.0.3
• Component/s: Java
• Environment: Java 17
• External issue URL: https://shibboleth.atlassian.net/browse/OSJ-400
• Assignee: Colm O hEigeartaigh
• Reporter: Brent Putman
• Created: 03/Apr/24 01:10
• Updated: 05/Nov/24 06:38
• Resolved: 03/May/24 14:12

Description

The 3.0.4 release (and I assume also the corresponding 4.0.x release, but I can't test that) introduced a regression in  XMLCipher related to the new support for ECDH and AgreementMethod.

The code in XMLCipher#getAlgorithmParameters(EncryptedKey) seems to implicitly assume that if there are AgreementMethod elements present in the KeyInfo, that it needs to actually "do" key agreement, so it unconditionally casts the supplied input Key to PrivateKey (assuming it is an ECPrivateKey, for example).

This assumption doesn't hold, because the caller may have already performed the key agreement op independently on the KeyInfo data, and has inited XMLCipher with the resulting SecretKey. OpenSAML implemented ECDH (and DH classic) support several years ago using this approach.

Issue Links

• links to: GitHub Pull Request #305