The IPv6 updates to the XDMCP standard include an updated authentication protocol,
XDM-AUTHENTICATION-2, which allows larger addresses to support IPv6, and replaces
Triple-DES with AES for encryption.
xdm should be updated to support this new protocol.
The XDM-AUTHENTICATION-2 was pulled from the final version of the IPv6 changes
to the standards documents as no one had implemented it. The idea still seems
reasonable, should anyone with sufficient interest and knowledge of the
cryptography issues want to pick it up and provide an implementation.
Sorry about the phenomenal bug spam, guys. Adding xorg-team@ to the QA contact so bugs don't get lost in future.