Welcome to the resource topic for 2020/1311
Title:
Cryptanalysis of Feistel-Based Format-Preserving Encryption
Authors: Orr Dunkelman, Abhishek Kumar, Eran Lambooij, Somitra Kumar Sanadhya
Abstract:Format-Preserving Encryption (FPE) is a method to encrypt non-standard domains, thus allowing for securely encrypting not only binary strings, but also special domains, e.g., social security numbers into social security numbers. The need for those resulted in a few standardized constructions such as the NIST standardized FF1 and FF3-1 and the Korean Standards FEA-1 and FEA-2. Moreover, there are currently efforts both in ANSI and in ISO to include such block ciphers to standards (e.g., the ANSI X9.124 discussing encryption for financial services). Most of the proposed FPE schemes, such as the NIST standardized FF1 and FF3-1 and the Korean Standards FEA-1 and FEA-2, are based on a Feistel construction with pseudo-random round functions. Moreover, to mitigate enumeration attacks against the possibly small domains, they all employ tweaks, which enrich the actual domain sizes. In this paper we present distinguishing attacks against Feistel-based FPEs. We show a distinguishing attack against the full FF1 with data complexity of 2^{60} 20-bit plaintexts, against the full FF3-1 with data complexity of 2^{40} 20-bit plaintexts. For FEA-1 with 128-bit, 192-bit and 256-bit keys, the data complexity of the distinguishing attack is 2^{32}, 2^{40}, and 2^{48} 8-bit plaintexts, respectively. The data complexity of the distinguishing attack against the full FEA-2 with 128-bit, 192-bit and 256-bit is 2^{56}, 2^{68}, and 2^{80} 8-bit plaintexts, respectively. Moreover, we show how to extend the distinguishing attack on FEA-1 and FEA-2 using 192-bit and 256-bit keys into key recovery attacks with time complexity 2^{136} (for both attacks).
ePrint: https://eprint.iacr.org/2020/1311
See all topics related to this paper.
Feel free to post resources that are related to this paper below.
Example resources include: implementations, explanation materials, talks, slides, links to previous discussions on other websites.
For more information, see the rules for Resource Topics .