This repository contains a VHDL and Python implementation of the Speck cipher as specified in NSA documents [0,1]. The VHDL code of Speck is pipelined and allows to define the desired key and block sizes through generics. CTR is available as cipher mode for Speck in hardware. Tests are provided for both VHDL and Python.

Do not use this code to process sensitive information. While we have done our best to ensure correctness, the code has not been audited and may be susceptible to cryptographic attacks.

The VHDL implementation of the cipher requires a VHDL-93 compatible synthesis tool. The VHDL testbenches use VHDL-2008 and therefore require a simulation tool that supports this standard, e.g. Vivado 2016.4 and later. The Python implementation requires Python 3.6 or later.

The following images show the RTL schematics of Speck 64 96. CTR Mode

Encryption Pipeline

Encryption Round

[0] R. Beaulieu, D. Shors, J. Smith, S. Treatman-Clark, B. Weeks and L. Wingers, "The SIMON and SPECK Families of Lightweight Block Ciphers", Cryptology ePrint Archive, Report 2013/404, Available: https://eprint.iacr.org/2013/404.pdf

[1] R. Beaulieu, D. Shors, J. Smith, S. Treatman-Clark, B. Weeks and L. Wingers, "SIMON and SPECK Implementation Guide", NSA Cybersecurity, June 26, 2018. [Online]. Available: https://nsacyber.github.io/simon-speck/implementations/ImplementationGuide1.1.pdf