Format-Preserving Encryption for Character Data

This paper presents FPE (Formatpreserving Encryption) for character data in both fixed-width and variable-width encoding. Previous researches only studied FPE for fixed-width character data. In this paper, FPE for character data is categorized into NPE (Number-preserving Encryption) and LPE (Length-preserving Encryption). The schemes related to NPE and LPE are proposed to encrypt fixed-width and variable-width character data, respectively. Furthermore, the paper provides a general solution for both data types. The security and efficiency of these schemes are analyzed and verified.