I wanted to register a @live.com e-mail address, but it says it can't register an e-mail address having a password that contains more than 16 chars.Why? So that it would be easier to get the real password? (if the password hashes were stolen . . .)
Why does live.com limit passwords to 16 characters?
microsoft
Actually because when you md5 a password it calculates a hash. Then the string is longer than 16 characters some hashes can collide between them.For example if md5(noroof) gives 9ce405c98406f2f6d5326ee6b51d19cd it is possible that md5(ididntfixedmyroofwhenicould) could give the same hash 9ce405c98406f2f6d5326ee6b51d19cd. Remember that hashes are composed by with 32 characters of 0123456789abcdf (for md5 in this case).Maybe they force 16 character because the algorithm that computes the hash assures that will not have a collision in the database with a previously saved password.