View Full Version : Bruteforcing DES

February 20th, 2006, 18:59
I have some data I think crypted by DES.I want to bruteforce it.So before reinventing the wheel,is there any software to bruteforce DES? like
descrack plaintext ciphertext startofkey

Also if there is no such program what should be the strategy for bruteforce.AFAIK although key is 64 bit 8 bits used for parity so there are keys which gives same result.So we have to eliminate them too to decrerase key space to 56 bit.I will appreciate any tips on this subject.


February 23rd, 2006, 15:33
Well, it's almost as easy to write your own as to google for one. Here are ten different C implementations of DES from the applied crypto book:


Any one of these will suit your needs. The trouble is, 56 bits is still a lot! It could take weeks or months on a single PC.

However, you could write to Paul Kocher at cryptography.com and ask how much he charges to rent the DEScrack machine he built. It'll do it in a couple of days.

February 26th, 2006, 07:56
Thanks for the links.I have already implemented DES routines from SSLeay package.I dont have any problem with it.I thought there is maybe some program written already for this purpose.Thanks again.

March 6th, 2006, 19:04
I have found another implemantation of DES which is written in MMX and using some technique called bitslice.I have tried to implement it but I failed.Could anybody with good understanding of this algorithm help to implement it?I have downloaded http://http.distributed.net/pub/dcti/source/archives/pub-20000502.zip.It has Des folder with such implemantaion.I have used obj files in it and tried to call
push offset des_key
push offset ciphertext
push offset plaintext
call _whack16

but it didnt worked.Thanks in advance.

June 11th, 2006, 05:24
Have you tried John the Ripper password cracker (http://www.openwall.com/john/)? It supports many brute-force cracking algorithm, includes DES, 3DES...