I have recently seen CAMELLIA, SEED and IDEA cipher suites in use for HTTPS on a web server and am unsure what to suggest to the owner. The keys in use are all over 128 bits in length and standard OpenSSL is in use.
IDEA was deprecated in rfc5469 due to it not seeing widespread use but may not actually be insecure.
Possible reasons to use the above cipher suites may involve being excessively paranoid about potential NSA interference and wanting to use Japanese / European / South Korean cipher suites instead. It is not affected by any local legal requirements to use these ciphers.
Possible reasons not to use these ciphers include they are not widely used across the industry so are likely to have been subject to less research by the security community compared to AES or other alternatives. It is possible someone may be able to develop side channel attacks by adapting those used against other ciphers but this is extremely unlikely for this server. Support from them has been removed from most modern browsers and I cant think of any situation where a client that could use these cipher suites would not support AES which was also available.
Beyond alerting the owner to the deprecation of IDEA and suggesting that it is generally a good idea to use the de-facto industry standard cipher suites, as these have had the most research performed against them, is there anything else I should be aware of?