Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <adc8d256e096d00aabcdcb94980ddcc9@smtp.hushmail.com>
Date: Sun, 23 Apr 2023 12:46:07 +0200
From: magnum <magnumripper@...hmail.com>
To: john-dev@...ts.openwall.com
Subject: Re: Birthday paradox

On 2023-04-23 12:28, magnum wrote:
> Starting with no bitmap (BLOOM_K=0 disables):
> 
> Using default input encoding: UTF-8
> Loaded 256 password hashes with no different salts (NT-opencl [MD4 OpenCL])
> 256 hashes: Hash table in local memory (2468 B); no filter.
> Offset tbl 380 B, Hash tbl 2088 B, Results 3076 B, Dupe bmp 36 B, TOTAL 
> on GPU: 5580 B
> LWS=256 GWS=34816 (136 blocks) x9025
> Press 'q' or Ctrl-C to abort, 'h' for help, almost any other key for status
> 25g 0:00:00:24 DONE (2023-04-23 12:04) 1.004g/s *30628Mp/s* 30628Mc/s 
> 7190GC/s Dev#2:66°C util:95% aaUh}|..aaUh}|
> Remaining 231 password hashes with no different salts
> Session completed.
> 735091890625 crypts, fp from bitmap: 1/4153061529 (0.00%), 177 hash 
> table lookups

Same without even using local memory:

256 hashes: Hash table in global memory (2532 B); no filter.
Offset tbl 412 B, Hash tbl 2120 B, Results 3076 B, Dupe bmp 36 B, TOTAL 
on GPU: 5644 B
LWS=256 GWS=34816 (136 blocks) x9025
Press 'q' or Ctrl-C to abort, 'h' for help, almost any other key for status
25g 0:00:00:25 DONE (2023-04-23 12:36) 0.9723g/s *29403Mp/s* 29403Mc/s 
6902GC/s Dev#2:67°C util:95% aaUh}|..aaUh}|
Remaining 231 password hashes with no different salts
Session completed.
735091890625 crypts, fp from bitmap: 1/3910063248 (0.00%), 188 hash 
table lookups

The reported "fp from bitmap" in the no-bitmap case are 32-bit false 
positives from the hash table. They should be the same above but somehow 
isn't.  I regard it as some effect of the mentioned randomness in the 
PHT (as you can see the sizes differ as well) but in the no-bitmap case 
it still puzzles me - we're comparing an actual MD4 hash word by word.

magnum

Powered by blists - more mailing lists

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.