Deterministic Counter in Tweak (DCT)

DCT is a beyond-birthday-bound (BBB) secure Deterministic Authenticted Encryption (DAE) scheme inspired by the Counter-in-Tweak encryption scheme by Peyrin and Seurin.

DCT combines a fast almost-XOR-universal family of hash with a single call to a 2n-bit block cipher, and a BBB-secure encryption scheme. First, we describe our construction generically with three independent keys, one for each component. Next, we present an efficient instantiation which

1. requires only a single key,
2. provides software efficiency by encrypting at less than two cycles per byte on current x64 processors, and
3. produces only the minimal t-bit stretch for t bit authenticity.

At the moment, we leave open two minor aspects for future work: our current generic construction is defined for messages of at least 2n-t bits, and the verification algorithm requires the inverse of the used 2n-bit block cipher and the encryption scheme.

Academic Paper:

Christian Forler, Eik List, Stefan Lucks, and Jakob Wenzel: Efficient Beyond- Birthday-Bound-Secure Deterministic Authenticated Encryption with Minimal Stretch. IACR Cryptology ePrint Archive, 2016:407, 2016. https://eprint.iacr.org/2016/407

Instance:

Our instantiation uses

• The efficient Bernstein-Rabin-Winograd (BRW) BRW-256 as 2n-bit hash function [Ber07].
• Simpira [GM16] for 2n-bit blocks as 2n-bit cipher.
• The Counter-in-Tweak (CTRT) encryption scheme [PS15], instantiated with the Deoxys-BC-128-128 [JNP14] tweakable block cipher.

Content:

• C reference implementation
• C optimized implementation (requires the AES-NI, pclmulqdq, and SSE4.1 instructions)

Make Targets:

• ref-tests: Reference implementation tests
• sse-tests: Optimized implementation tests
• sse-bench: Optimized implementation benchmarks
• all
• clean

Dependencies:

• clang/gcc
• make

References:

[Ber07] Daniel J. Bernstein. Polynomial evaluation and message authentication. http://cr.yp.to/papers, permanent ID: b1ef3f2d385a926123e1517392e20f8c, 2, 2007.

[GM16] Shay Gueron and Nicky Mouha. Simpira v2: A Family of Efficient Permutations Using the AES Round Function. IACR Cryptology ePrint Archive, 2016:122, 2016.

[JNP14] Jeremy Jean, Ivica Nikolic, and Thomas Peyrin. Tweaks and Keys for Block Ciphers: The TWEAKEY Framework. In ASIACRYPT (2), volume 8874 of LNCS, pages 274–288, 2014.

[PS15] Thomas Peyrin and Yannick Seurin. Counter-in-Tweak: Authenticated Encryption Modes for Tweakable Block Ciphers. IACR Cryptology ePrint Archive, 2015:1049, 2015.