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Re^2: Short & Sweet Encryption?

by thor (Priest)
on Jul 30, 2006 at 15:21 UTC ( #564626=note: print w/ replies, xml ) Need Help??


in reply to Re: Short & Sweet Encryption?
in thread Short & Sweet Encryption?

xor-ing is the method used by the One-Time pad, so to say that it's inherintly insecure is somewhat unfair. Also, you'd probably want to do something to bring the characters back into printable range, which you don't do above.

thor

The only easy day was yesterday


Comment on Re^2: Short & Sweet Encryption?
Re^3: Short & Sweet Encryption?
by Anonymous Monk on Jul 30, 2006 at 15:55 UTC

    To encode a high quality 4MP image, XOR requires a 17,000,000 bit (non-reusable) key. Other top ciphers require a 64 or 128 bit (reusable) key. XOR requires extra bits to compensate for its inherent insecurity.

    If your key management system is secure enough to exchange and store a key as big as the data to encrypt, why don't you the system to protect the plaintext instead of the key?

      One Time Pads do have their application. For instance, the Russians used them to great effect for a while during the Cold War. Where they tripped up was they started to reuse keys. The One Time Pad assumes a random key. Once it starts repeating, it becomes a Vigenère Cipher, which has trivial to implement attacks against it.

      As far as why you would implement such a thing, I leave that to your imagination. I wasn't even saying that it was a particularly good choice for this application. I was just defending xor-based ciphers in general.

      thor

      The only easy day was yesterday

Re^3: Short & Sweet Encryption?
by syphilis (Canon) on Jul 30, 2006 at 23:12 UTC
    xor-ing is the method used by the One-Time pad, so to say that it's inherintly insecure is somewhat unfair

    I would never say that. The only shortcoming of a properly constructed one-time pad is that it (or a copy of it) may fall into the wrong hands.

    Also, you'd probably want to do something to bring the characters back into printable range, which you don't do above

    I don't see any need to do that. (Apologies if I'm being dumb :-)

    Cheers,
    Rob

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