One-time pad
= One-time pad
{wiki}
For messages in a <finite additive group>, a one-time pad encrypts $X$ as $C=X+K$, where the key $K$ is uniform and <independent random variables>[independent] of $X$, as long as the message, and never reused. Then $C$ is uniform and <independent random variables>[independent] of $X$, giving <perfect secrecy>.