[EMAIL PROTECTED] wrote: > John Machin wrote: >> On Mar 22, 1:11 am, [EMAIL PROTECTED] wrote: >>> A collision sequence is not so rare. >>>>>> [ hash( 2**i ) for i in range( 0, 256, 32 ) ] >>> [1, 1, 1, 1, 1, 1, 1, 1]
>> Bryan did qualify his remarks: "If we exclude the case where an >> adversary is choosing the keys, ..." > > Some adversary. What, you mean, my boss or my customers? We mean that the party supplying the keys deliberately chose them to make the hash table inefficient. In this thread the goal is efficiency; a party working toward an opposing goal is an adversary. If you find real-world data sets that tend to induce bad-case behavior in Python's hash, please do tell. It would be reason enough to adjust the hash function. The hashes in popular software such as Python are already quite well vetted. Even a hash function that behaves as a random oracle has worst-case quadratic-time in the algorithm here, but that's an issue in theory and not in serving customers. -- --Bryan -- http://mail.python.org/mailman/listinfo/python-list
