Decryption is the act of transforming a ciphertext into a plaintext. The opposite process is encryption.

Let `K`

be a set of keys, `M`

be a set of plaintext messages, and
`C`

be a set of ciphertext messages.
The bijection `D`

, where _{k}:C→M`k`

∈`K`

,
is a decryption function or decryption transformation.

L. R. Knudsen, M. J. B. Robshaw, *The Block Cipher Companion.* Springer, 2011.

Copyright © 2014 Barry Watson. All rights reserved.