This is an example of how the bitwise XOR can be used to make a simple encryption system.
Suppose Alice wants to send the message
CAT to Bob using the key
First: Convert the characters in the message to ASCII:
C = 01000011
A = 01000001
T = 01010100
Second: Alice shares the key with Bob.
Third: Perform bitwise XOR of each bitstring in the message with the key. (Using
xor for this since math notation not supported here.)
01000011 xor 11000101 = 10000110
01000001 xor 11000101 = 10000100
01010100 xor 11000101 = 10010001
Fourth: Alice sends the encrypted message
01000011 01000001 01010100 to Bob. If an eavesdropper intercepted the message and tried convert this sequence back to ASCII characters, they'd get three indecipherable control characters. (Check the table.)
Fifth: Bob receives the message and XOR's each bitstring with the key:
10000110 xor 11000101 = 01000011
10000100 xor 11000101 = 01000001
10010001 xor 11000101 = 01010100
Sixth: Bob does a reverse lookup in the ASCII table (or using a computer) to convert from binary back to characters:
01000011 = C
01000001 = A
01010100 = T
And that's the original message.