Confidentiality is concerned with keeping information secret. It is a key information security objective.

A cipher can be used to achieve confidentiality.
As an example, if Alice wishes to communicate secretly with Bob, then they would choose a keypair
`(e,d)`

which would give the encryption function
`E`

and the decryption function
_{e}`D`

. If Alice's plaintext is _{d}`m`

then Alice sends the ciphertext `c=E`

to Bob.
Bob can then compute the original plaintext as _{e}(m)`D`

.
_{d}(c)=m

A. Menzes, P. van Oorschot, and S. Vanstone, *Handbook of Applied Cryptography.* CRC Press, 1996.

Copyright © 2014 Barry Watson. All rights reserved.