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View Full Version : Decode an MD5 string - help pls


newbie2this
January 14th, 2002, 06:25
OK - First time in this forum but I need some help. I am trying to decode an MD5 string e9fe40e4d15ce94e854e83fb82b405b8 I am trying MD5 Crack which is taking absolutely ages (2 weeks so far) with no results. The original string had 0 and X's in it with spaces, but I was told to remove these to run the program.

Does anyone have any ideas as to how I can crack this without taking ages and ages. Any ideas would be appreciated. Email me at eoddynamite@hotmail.com

Kythen
January 14th, 2002, 15:13
Well my friend, I hate to break it to you but you're *not* going to reverse an MD5 signature. That's one of the points of using the hash of a plaintext like that... there are waaaayyy too many possible plaintexts to search through! As for that MD5Crack program, I've never heard of it and while it may have something useful, I'm very skeptical of it.

Now what exactly are you trying to do this for? Is this MD5 signature part of some registration scheme or something? Please give us more details and maybe we can help you down a different path.

Cheers!
Kythen

newbie2this
January 15th, 2002, 03:51
thanks for the response - I kind of guessed that you were going to say that. However the MD5 program will work (brute force) but it may take over a year which is unacceptable.
Ethical or not I am trying to decode a encrypted password that is within a cable modem config file - to tweak it. I need the same password as the router so as the 2 are compared, I get authentication. If no password, no access !!
Any ideas, or am I barking up the wrong tree ???

Kythen
January 15th, 2002, 13:47
I think you'd be very lucky to brute force it in a year, but that's kinda irrelevant. We've firmly established this is not exactly something you want to brute-force

As for your objective, I'm not a hardware person. About all I can suggest is reverse engineering the software that controls the modem and seeing if the password comparison is done in hardware or the software. If it's done in the program, you're all good... if not, sorry but I couldn't tell you what to do.

Snatch
January 15th, 2002, 14:51
newbie2this: Please explain more and more and more about how you have done this. I have 2 cable modems and I would love to do some tweaks on them but I thought that all the handshaking with the router etc was part of the hardware. How did you find that MD5 hash string? If it is part of the software you could be in luck. There might be other ways around what you are trying to do. Tell us how you have gotten the MD5 string and how the modem works please then we can give you some thoughtful answers.

Snatch

B-Boy
January 15th, 2002, 17:34
if the md5 string is in the config file and you have access to it.. why not just put some dummy self-encoded md5 string into it?..

jomamameister
January 17th, 2002, 15:55
using a dummy md5 hash won't work, except to generate an error. the md5 hash algorithm doesn't really recognize anything. it merely produces a hash of the input. the recognition of an error must come from your own prog through some sort of a comparison routine. simply put, if i input "jomamameister" and use the md5 hash i get "580c4ea440a04b5fef88f8087b910a7c".
so if you input anything else, you will just generate another md5 hash string. you couldn't intuitively "guess" the right input. or generate the "right" hash without the "right" input. the odds are against you if you look right below.
you can do the math yourself. each character in this string can be (26 lower case letters plus 10 numbers ) = 36 possible choices all independent of the others. so you can have 36 ^ 32 power of choices. this is quite a huge number. not only that, but you can manipulate the input before sending it to the hash algorithm or hash it again after going through a cycle. it's up to you. how complex you, as the programmer want to make this thing.
it may be better to look for another way around this prog. take care. if you think that's bad, try the sha256 or sha512.
jomamameister