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File: 1470704111973.png (32.92 KB, 300x276, 1470166361108.jpg)

No.34898

How would one go about decoding a numeric cipher?

Also cryptography thread

  No.34899

File: 1470709873341.png (8.44 MB, 200x200, Applied Cryptography (2ed) - B. Schneier (1996).pdf)

This is objectively the best book on cryptography

  No.34902

>>/tech/res/26059.html#26068
Is there any reason you think cryptography isn't technology

  No.34904

>>34902
I figured that because cryptography is heavily involved with cyber security, it would fit in /cyb/ more than in /tech/. I also thought it would be more likely to gather more attention in the same board that the hackers and security experts/enthusiasts hang out.

  No.34908

>>34898
>How would one go about decoding a numeric cipher?

bang your head against it for a month.

  No.34921

>>34898
If you have one you want to crack post it so we can give it a shot.

>>34908
Also this

  No.34930

Here is an EXCELLENT intro to cipher cracking:

https://inventwithpython.com/hacking/chapters/

  No.34931

File: 1470798897431.png (3.73 MB, 200x200, Hacking-Secret-Ciphers-With-Python.pdf)

>>34930
And here is the .pdf if you're into that kind of thing.

  No.34933

File: 1470802085849.png (118.96 KB, 200x200, 1470800483536.jpg)

I got a password protected rar that needs to be opened. The hints for the password are:

76.353503184713375796178343949045
1756.2038216560509554140127388535
1603.4904458598726114649681528662
1298.0636942675159235668789808917
1915.0159744408945686900958466454
1221.7070063694267515923566878981
1603.4904458598726114649681528662
1068.9936305732484076433121019108

01000100

x = (n*p) / pc

The picture in my post might be relevant too. Anyone got any clues what cipher it could be / what the process is? The file is only available for 2 days here: http://expirebox.com/download/e83c64f4e2fdce5f68732d91e6dc2e7c.html

Any help would be appreciated

  No.34936

>>34933
x is probably the ciphertext, n is probably the plaintext, c is probably the constant given, p is inconsequential because it is cancelled out (x = np/pc -> x = n/c) unless p and pc are different things. It's really unclear.

  No.34937

still >>34936

either way the encryption itself is extremely weak, they've just obfuscated it significantly, which is even more annoying.

  No.34938

>>34936
>>34937
what confuses me are the decimals, I don't see how I'd get them back to text.

So far I assumed x would be the cipher end result, for example 76.353.. and n would indicate the length of the plaintext, p stand for a prime. I think pc is different from the p in (n*p), wouldn't make any sense.

  No.34948

>>34936
I think the lower pc is different as otherwise it would be written as p*c, right?

>>34933
Got the original post, as if this picture is relevant then it could make the process a whole lot harder.


Things I played around with:
01000100 = 68 [dec] = 44 [hex]

All those numbers multiplied give:
1119301859398908872916874 . 59733115802066384500139372453784907161446149870635329125804568617466446668654915987720145155955616313847841409942622599797733192456332585135874626472108931912918985564667732479999000146756336473640389239329896903536503839752

Not a prime, not very helpful.

  No.34961

>>34948
It's still a non prime divided by 2, 3, 4, 5, so on?