Performance Analysis of Format-Preserving Encryption Based on Unbalanced-feistel Structure

Abstract

Format-Preserving Encryption (FPE) is used to produce a ciphertext with the same length and format as a plaintext. Some approaches to do that are a prefix cipher, a cycle walking, a feistel network and so on. In this paper, we present format-preserving encryption using the unbalanced-feistel structure. We apply our construction to FFX, VAES3 and BPS schemes, which are modes of operation for FPE. We also analyze the performance of three unbalanced-feistel FPE schemes over block ciphers. VAES3 using 128-bit AES encrypts credit card numbers at 5,924,000bps.