Logic Gate

What is XOR?

exclusive or (XOR) 1 , 2

  • used in cryptography because it let's us 'flip' the bits using a mask in a reversable operations

  • p1 (+) p2 (+) ... (+) pn is true if the number of variables with the value true (1) is odd, because the XOR is associative

  • XOR is the same as addition modulo 2

    • p1 (+) p2 (+) ... (+) pn == ( p1 + p2 + ... + pn) % 2 - dividing mod 2 is one way to determine if a number is even or odd
    • Only the variables that have value 1 contribute to the sum, that determines how many variables have value 1

  • doing parity check

    • kind of checksum: use the XOR to check whether there is the flip