It also slows down cracking numerous passwords in parallel using a dictionary/heuristic approach a la john the ripper - without a salt, you can calculate the hash of each password guess once, and then scan through an entire shadow file for the hash. With salts, you have to hash each guess once per user in the list, or at least per user you're interested in attacking. In the case of the postgres passwords, the user name seems to act as a sort of "public" salt. Knowing some user IDs, you might precompute a set of hashes for each targetted user, in anticipation of getting your hands on the password hashes later. Mark > -----Original Message----- > From: Mike Fratto > I am pretty sure the intent the salt is to make > pre-computation of a dictionaries infeasable due to storage > requirements. It doesn't really add to the keyspace because > the salt is known and doesn't have to be guessed. --- end of sensible content --- This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail.
