Hey List, I'm wondering if anyone has an opinion on a "recommended" association timeout for OpenId OP/RP implementations?
I think it takes something like 2^80 operations to brute force SHA1 (the least secure OpenId HMAC Association type). Supposedly, in 2005 SHA1 was "sort of" broken by a Chinese researcher (see here: http://www.schneier.com/blog/archives/2005/02/sha1_broken.html) but according to Bruce Schneier, HMAC is not affected by this development (only digital signatures are). All that to say, it seems like it would still take a long time to brute force an SHA1 association (SHA256 even longer), so I'm wondering what people's thoughts are where OpenId implementation should set this number by default. For example, one of the most popular Java OpenId 2.0 implementations currently uses a 30 minute expiration. What about 3 days? 7 days? Longer? I guess I'm trying to figure out where the "balance between security and convenience" decision should be made. Thanks for your input! David _______________________________________________ security mailing list [email protected] http://openid.net/mailman/listinfo/security
