For the past few months, there has been much talk of the likelihood that
the AES process will come out with two ciphers, not one. This was talked
about at the SAAG meeting in Adelaide, and folks from NIST said that this
was indeed the current thinking.
RFC 2440 and the current 2440bis draft has algorithm IDs that say "Reserved
for AES with 128-bit key" and so on. It might be wise to allocate another
three and specify that the actual algorithms used for IDs 7, 8, and 9 (and
probably 11, 12, and 13) will be defined by a future RFC.
--Paul Hoffman, Director
--Internet Mail Consortium