the security of XOR "encryption" is dependent on the length of the key as follows:

if the key is longer than the message being encrypted and the key is perfectly random, it is provably unbreakable (it's just a one-time pad).

if the key is shorter than the message (so that it has to be repeated to encrypt the entire message), it's trivial to break. using XOR with a key that's repeated is essentially a vigenere cipher and can be broken quite painlessly by looking at the index of coincidence. don't use this method unless you really don't care if the encryption is broken, because it will be by the first hacker who decides to try.

anders pearson

In reply to Re: How secure is XOR encryption? by thraxil
in thread How secure is XOR encryption? by talexb

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