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Re: SSL trouble
Will French writes
>>> Please don't do anything like this. This will prevent
>>> people like me who prefer the "random" method from
>> You can't use the random method if the CRACK is using a
>> sequential search. It just doesn't fit!
> Hehe... I've always been a bit of a misfit.
>> You can't ACK something which has not been allocated to you.
> But I could announce it on the list.
Then what do you care about the group's procedures? It doesn't
"prevent you from participating" --- you *aren't* participating.
You're attempting to solve the problem on your own.
Statistically, the "random" methods are no different than everyone just
working independently at solving the problem.
I, too, don't recall my statistics well enough, but let me take a shot
at it, and anyone who wants to, please check me...
The probability of having failed to search a particular segment (the
one with the key) after selecting k of n segments at random with
replacement is (1-1/n)^k, whereas in a sequential search from a random
starting point, (or, equivalently, random without replacement) the
probability is k/n.
Assume the segments are farmed out in 2^24 segments of 2^16 keys each
(I don't recall what the current programs use). In the sequential case,
it's even money you'll find the key after searching 8,388,609
segments. In the random case, it's not even money until 11,629,080
segments --- 39% longer. It's when you're "unlucky" that the random
case gets *much* worse. To search 90% of the keyspace takes 15,099,495
sequential searches, but 38,630,967 --- a 156% difference.
Here's the table:
% k-space random sequential percent
searched method method difference
-------- ---------- --------- ----
10 1767657 1677722 5
25 4826505 4194305 15
50 11629080 8388609 39
75 23258160 12582913 85
90 38630967 15099495 156
99 77261933 16609444 365
99.9 115892899 16760439 591
Changing the segment size doesn't affect the results very much, as
a table for 10 bit segments shows:
50 744261117 536870912 37
90 2472381916 966367641 156
The random method is a little more than 1/3 worse in the typical
case, but *lots* worse in the worst cases.