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Unknown encryption |
Therma
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Posts: 33
Location: DENMARK
Joined: 07.12.07
Rank: Apprentice |
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Okay, so I get a dump of a text that has been encrypted with a home-made algorithm. Which I wanna try and break.
But where should I start?
If anyone has some experience with something like this, I would like to hear what your first step would be. And maybe second and third steps also 
Thanks in advance.
I hate lying to you, it's just the best way to keep you from knowing the truth.. |
 
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RE: Unknown encryption |
COM
Banned
Posts: 800
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Joined: 31.08.07
Rank: God |
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Frequencies, starting with standard letter frequency. Though having absolutely no knowledge about the encryption whatsoever leaves you pretty crippled.
K'aem'nhi kh'rn, K'aem'nhi kh'r, K'aem'nhi kh'rmnu.
I'a Y'gs-Othoth! |
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RE: Unknown encryption |
suid
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Start by entering simple strings and see what the result is. Then gradually increase the length of the string to try and get a feel for what the algorithm is doing. It's kind of a brute force method but not a blind one. Your mileage may vary. I'm assuming you can do these steps. After you get used to seeing normal strings in their hashed formats, it should begin to come natural for you to reverse the steps starting with a hash.
If this is good advice, then I'm glad I could contribute. Otherwise, see what someone more skilled in this area can suggest. |
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RE: Unknown encryption |
COM
Banned
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suid wrote:
Start by entering simple strings and see what the result is.
Or well, yeah, this; if you have access to deciding and encrypting your own plaintexts. Based on the initial post though, I assume that isn't the case.
K'aem'nhi kh'rn, K'aem'nhi kh'r, K'aem'nhi kh'rmnu.
I'a Y'gs-Othoth! |
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RE: Unknown encryption |
ynori7
Future Emperor of Earth
Posts: 1481
Location: #valhalla
Joined: 08.10.07
Rank: Diabolical |
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If it's a polyalphabetic cipher you may want to try using Friedman's Index of Coincidence method. That'll probably only work if you've got a pretty good sized set of crypt-text.
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RE: Unknown encryption |
Therma
Member
Posts: 33
Location: DENMARK
Joined: 07.12.07
Rank: Apprentice |
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Thanks for the comments guys.
Yea, I have never tried decrypting from this level and its not a polyalphabetic cipher. I think I might have to ask my friend for a bit more information.
Think it might be impossible, since I dont really know what Im looking for, what language ect..
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RE: Unknown encryption |
ynori7
Future Emperor of Earth
Posts: 1481
Location: #valhalla
Joined: 08.10.07
Rank: Diabolical |
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Therma wrote:
its not a polyalphabetic cipher
Out of curiosity, how do you know that? Did your friend give you more information about this cipher that you didn't tell us?
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