e/Format-Preserving Encryption

Information
has gloss	eng: In cryptography, format-preserving encryption (FPE) is a mode of operation of a block cipher that keeps the format of the encrypted data the same as the format of the unencrypted data. There are ways to implement FPE that are provably as secure as the underlying block cipher. How to do this was first described in a paper by cryptographers John Black and Phillip Rogaway, which described three ways to do this. FPE is NOT an approved MODE of the AES algorithm and hence its not FIPS Compliant. An approach based on one of these techniques has been accepted by NIST for consideration as an approved mode of the AES algorithm under the name "Feistel Finite Set Encryption Mode (FFSEM)". The following discussion uses AES as the underlying block cipher, but the same results are also true for any other block cipher.
lexicalization	eng: Format Preserving Encryption
lexicalization	eng: Format-Preserving Encryption
instance of	e/Block cipher