DES-ECB: mask on plain text? - Printable Version

DES-ECB: mask on plain text? - Printable Version

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DES-ECB: mask on plain text? - 1010 - 02-16-2017

Hi, I'm trying to run hashcat to find DES-ECB key. What I know is part of plain text and full encrypted text. Is there a way to apply a mask on the plaintext so that hashcat only consideres part of the plaintext, for example only 6 of 8 bytes? I realize this will result in false positives but that's fine.

Example:

Decrypted bytes:

Code:
AA BB CC DD EE FF ?? ??

DES-ECB Encrypted bytes:

Code:
01 02 03 04 05 06 07 08

Now I want to find all DES keys that will decrypt 0102030405060708 into AABBCCDDEEFFxxxx where xxxx doesn't matter, I just want the keys, any of it, that produces

Code:
AABBCCDDEEFF

by decrypting

Code:
0102030405060708

thanks

RE: DES-ECB: mask on plain text? - atom - 02-16-2017

Yes, but we'd need to switch from encrypt to decrypt and then match out the bits you don't care about. So that's possible but requires a kernel rewrite

RE: DES-ECB: mask on plain text? - 1010 - 02-16-2017

(02-16-2017, 09:32 PM)atom Wrote: Yes, but we'd need to switch from encrypt to decrypt and then match out the bits you don't care about. So that's possible but requires a kernel rewrite

Thanks for letting me know, so it makes sense I couldn't figure out the command line parameters to do this... but what should I do in order to have this feature added?

RE: DES-ECB: mask on plain text? - MaxPower - 02-17-2017

(02-16-2017, 09:46 PM)1010 Wrote:
(02-16-2017, 09:32 PM)atom Wrote: Yes, but we'd need to switch from encrypt to decrypt and then match out the bits you don't care about. So that's possible but requires a kernel rewrite

Thanks for letting me know, so it makes sense I couldn't figure out the command line parameters to do this... but what should I do in order to have this feature added?

Hi 1010,

Apologies if this is seen as hijacking your thread but I think we may be trying to achieve a similar result.

I am currently looking at trying to do something similar except I have all the plain text but only the first part of the encrypted text. From my understanding of DES-ECB, encrypting and decrypting are the same process so maybe what we are trying to achieve is not too different.

I need to find all keys that return AA ?? ?? ?? ?? ?? ?? for a known plain text input.

I am trying to do this as one possible approach to ultimately finding the encryption key in DES-OFB.

I have only just started looking into the process of how to code this, maybe it would be worth working on it together? I would also be willing to contribute $$ if someone else feels they can get this happening much quicker as time is a bit of an issue for me.

Moderator - The forum rules don't appear to prohibit offering to pay to upgrade the code for everyone's future benefit, but if this is the case please feel free to edit my post to remove this reference.

MaxPower.

RE: DES-ECB: mask on plain text? - atom - 02-20-2017

Quote:I need to find all keys that return AA ?? ?? ?? ?? ?? ?? for a known plain text input.

That will be each 1/256th candidate? You will recieve millions. That's a very bad idea!