Paper 2015/585

SIMON and SPECK: Block Ciphers for the Internet of Things

Ray Beaulieu, Douglas Shors, Jason Smith, Stefan Treatman-Clark, Bryan Weeks, and Louis Wingers


The U.S. National Security Agency (NSA) developed the SIMON and SPECK families of lightweight block ciphers as an aid for securing applications in very constrained environments where AES may not be suitable. This paper summarizes the algorithms, their design rationale, along with current cryptanalysis and implementation results.

Note: We've updated Table 1 to include recent SIMON cryptanalysis results from Chen and Wang (2015/666). We've also edited the discussion of low-latency implementations, to include a PRINCE implementation from 2015/658, fix a reference, update one of our implementations, and tweak the wording.

Available format(s)
Secret-key cryptography
Publication info
Published elsewhere. will be presented at the NIST Lightweight Cryptography Workshop, and will appear on their web page. NIST has OK'ed posting here.
lightweight block cipher
Contact author(s)
djshors @ tycho ncsc mil
2015-07-10: last of 2 revisions
2015-06-21: received
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Short URL
Creative Commons Attribution


      author = {Ray Beaulieu and Douglas Shors and Jason Smith and Stefan Treatman-Clark and Bryan Weeks and Louis Wingers},
      title = {SIMON and SPECK: Block Ciphers for the Internet of Things},
      howpublished = {Cryptology ePrint Archive, Paper 2015/585},
      year = {2015},
      note = {\url{}},
      url = {}
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