SPF: A New Family of Efficient Format-Preserving Encryption Algorithms

Donghoon Chang, Mohona Ghosh, Kishan Chand Gupta, Arpan Jati, Abhishek Kumar, Dukjae Moon, Indranil Ghosh Ray, Somitra Kumar Sanadhya

Abstract: Commonly used encryption methods treat the plaintext merely as a stream of bits, disregarding any specific format that the data might have. In many situations, it is desirable and essential to have the ciphertext follow the same format as the plaintext. Moreover, ciphertext length expansion is also not allowed in these situations. Encryption of credit card numbers and social security numbers are the two most common examples of this requirement. Format-Preserving Encryption (FPE) is a symmetric key cryptographic primitive that is used to achieve this functionality. Initiated by the work of Black and Rogaway (CT-RSA 2002), many academic solutions have been proposed in literature that have focused on designing efficient FPE schemes. However, almost all the existing FPE schemes are based on Feistel construction and have efficiency issues.