My Encryption Algorithm...

This is a discussion on My Encryption Algorithm... within the A Brief History of Cprogramming.com forums, part of the Community Boards category; Since the statements were about public key, I felt it appropriate to illuminate this fact when replying to a comment ...

  1. #16
    C++ Witch laserlight's Avatar
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    Since the statements were about public key, I felt it appropriate to illuminate this fact when replying to a comment that changed the discussion from public key to private key in order to attempt to refute a statement made about public key crypto.
    Sounds like a misunderstanding. You were the first one to mention public key cryptography in this thread. citizen's comments were directly concerning Junior89's algorithm.

    While I provided a link to wikipedia to the original poster, that does not mean I advocate wikipedia as the supreme authority on all things crypto.
    Please do not make such assumptions, unless you wish your own statements to be "beneath contempt"
    I did not use Wikipedia as an authority here, though I did use it as a reference to double check. Schneier's website on Blowfish claims: "Vincent Rijmen's Ph.D. thesis includes a second-order differential attack on 4-round Blowfish that cannot be extended to more rounds."

    Last I checked you get AES-512 on thumbdrive encryption utilities.
    FIPS 197 states: "The AES algorithm is capable of using cryptographic keys of 128, 192, and 256 bits to encrypt and decrypt data in blocks of 128 bits."
    There is clearly no mention of 512 bit keys. I had the impression that primes are not needed for keys in symmetric ciphers.
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  2. #17
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    Quote Originally Posted by Junior89 View Post
    Well i couldn't seem to find a good forum (out there on the web) or anything like that for a little review and courteous criticism of my algorithm here. I'm sure it's stupid and insecure but i would like it if someone with some knowledge in the field could point out some of the biggest mistakes i made. I'm not naive and i do know that it probably isn't more than a dressed up XOR encryption but hey, i'll give it a shot!
    Block 1...
    Code:
    a, b, c, d
    a^L, b^L, c^L, d^L
    d^L, a^L, b^L, c^L
    d^L^R, a^L^R, b^L^R, c^L^R
    S(d^L^R), S(a^L^R), S(b^L^R), S(c^L^R)
    We can undo the S(), so it's just a problem of finding L^R, which is just a single XOR problem. Cracking XOR of plaintext is a problem solved long ago.


    On the other hand, look at block 3...
    Code:
    a, b, c, d
    a^R, b^R, c^R, d^R
    S(a^R), S(b^R), S(c^R), S(d^R)
    S(a^R)^L, S(b^R)^L, S(c^R)^L, S(d^R)^L
    S(d^R)^L, S(a^R)^L, S(b^R)^L, S(c^R)^L
    This is better, because L^R can't combine into a single XOR problem. The classic XOR methodology wouldn't work.



    To be honest, the biggest problems with this are...
    1) The permutation method is far too simple.
    2) It doesn't repeat enough times.

    I suggest trying to implement a Feistel cipher, what you have is very close to that, which is the basis of a lot of cryptography.
    Callou collei we'll code the way
    Of prime numbers and pings!

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