encryption - Why is XOR used in cryptography?

Question

Why is only XOR used in cryptographic algorithms, and other logic gates like OR, AND, and NOR are not used?

Answer 1

It isn't exactly true to say that the logical operation XOR is the only one used throughout all cryptography, however it is the only two way encryption where it is used exclusively.

Here is that explained:

Imagine you have a string of binary digits 10101 and you XOR the string 10111 with it you get 00010

now your original string is encoded and the second string becomes your key if you XOR your key with your encoded string you get your original string back.

XOR allows you to easily encrypt and decrypt a string, the other logic operations don't.

If you have a longer string you can repeat your key until its long enough for example if your string was 1010010011 then you'd simple write your key twice and it would become 1011110111 and XOR it with the new string

Here's a wikipedia link on the XOR cipher.

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