One round of Simon
|Designers||Ray Beaulieu, Douglas Shors, Jason Smith, Stefan Treatman-Clark, Bryan Weeks, Louis Wingers NSA|
|Key sizes||64, 72, 96, 128, 144, 192 or 256 bits|
|Block sizes||32, 48, 64, 96 or 128 bits|
|Structure||Balanced Feistel network|
|Rounds||32, 36, 42, 44, 52, 54, 68, 69 or 72 (depending on block and key size)|
|Speed||7.5 cpb (21.6 without SSE) on Intel Xeon 5640 (Simon128/128)|
|Best public cryptanalysis|
|Differential cryptanalysis can break 46 rounds of Simon128/128 with 2125.6 data, 240.6 bytes memory and time complexity of 2125.7 with success rate of 0.632.|
Simon is a family of lightweight block ciphers publicly released by the National Security Agency (NSA) in June 2013. Simon has been optimized for performance in hardware implementations, while its sister algorithm, Speck, has been optimized for software implementations.
Description of the cipher
The Simon block cipher is a balanced Feistel cipher with an n-bit word, and therefore the block length is 2n. The key length is a multiple of n by 2, 3, or 4, which is the value m. Therefore, a Simon cipher implementation is denoted as Simon2n/nm. For example, Simon64/128 refers to the cipher operating on a 64-bit plaintext block (n=32) that uses a 128-bit key. The block component of the cipher is uniform between the Simon implementations; however, the key generation logic is dependent on the implementation of 2, 3 or 4 keys.
Simon supports the following combinations of block sizes, key sizes and number of rounds:
|Block size (bits)||Key size (bits)||Rounds|
Opposition to ISO approval
German, Japanese and Israeli delegates to the International Organization for Standardization have opposed efforts by the NSA to standardise the Simon and Speck ciphers, citing concerns that the NSA is pushing for their standardisation with knowledge of exploitable weaknesses in the ciphers, based on partial evidence of weaknesses in the ciphers, lack of clear need for standardisation of the new ciphers, and the NSA's previous involvement in the creation and promotion of the backdoored Dual_EC_DRBG cryptographic algorithm.
- "Differential and Linear Cryptanalysis of Reduced-Round Simon". Retrieved 2014-04-16.
- Farzaneh Abed, Eik List, Stefan Lucks, Jakob Wenzel (5 March 2014). Differential Cryptanalysis of Round-Reduced Simon and Speck (PDF). FSE 2014. conference slides.
- Hoda Alkhzaimi, Martin Lauridsen (28 Aug 2013). "Cryptanalysis of the SIMON Family of Block Ciphers" (PDF).
- Schneier, Bruce. "SIMON and SPECK: New NSA Encryption Algorithms". Schneier on Security. Retrieved 2013-07-17.
- The Simon and Speck Families Of Lightwieght Block Ciphers (PDF). ePrint. Retrieved 2016-06-16.
- Claire Swedberg (17 July 2015). "NSA Offers Block Ciphers to Help Secure RFID Transmissions". RFID Journal.
- "Distrustful U.S. allies force spy agency to back down in encryption fight".
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