A One Time Pad is a information-theoretical secure encryption function. But what does that mean?

On a high level the One Time Pad is a simple XOR function that takes the input and xor’s that with a key-stream.

Encryption and decryption are identical.

Encryption: Takes the plaintext and the key-stream and xor’s it to get the cipher text.

Decryption: Takes the cipher text and the (same) key-stream and xor’s it to get the plaintext.

Some requirements of the One Time Pad are.

Key-stream should only be used once.

Key-stream should only be known by the sender and the receiver.

Key-stream should be generated by true randomness

Hence, the requirement are only on the key-stream, which obviously is the only input to the algorithm.

The beauty of the algorithm is the simplicity.

#one time pad

1.10 GEEK