On Sun, 04 Jan 2009 15:58:34 CST, Joe Greco said: > > Technically the only thing necessary to prevent > > this attack has already been done, and that is to stop issuing certs > > signed with MD5 so that no one else can create a rogue CA via this > > means. > > Are we certain that existing certs cannot be subverted?
The attack depends on being able to to jigger up *two* certs that have the same MD5 hash. Therefor, attacking an existing cert would require either: 1) That the existing cert be one of a pair (in other words, somebody else already knew about the current attack and also did it). or 2) Somebody has found a way to cause a collision to a specified MD5 hash (which is still impractical, AFAIK). If anybody has a subvertible cert, it's pretty safe to guess that they *know* they have such a cert, because they themselves *built* the cert that way.
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