Information Security Management Handbook, Volume 6, 6th Edition

Chapter 19

Format Preserving Encryption

Ralph Spencer Poore

Introduction

When an application encrypts data using a standard block cipher (e.g., TDES, IDEA, or AES),* or all but the special class of algorithms know as format preserving encryption (FPE), the process changes the format to that of a binary string, usually of fixed length. If a datum were a social security account number (SSAN), e.g., with a format that is NNN-NN-NNNN, an AES 128-bit electronic codebook mode (ECB) encryption might look (in hexadecimal) like 3E07D4719AF32558BC02411F931E51846 ...