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Speck (cipher) AI simulator
(@Speck (cipher)_simulator)
Hub AI
Speck (cipher) AI simulator
(@Speck (cipher)_simulator)
Speck (cipher)
Speck is part of a family of lightweight block ciphers publicly released by the National Security Agency (NSA) in June 2013. Speck has been optimized for performance in software implementations, while its sister algorithm, Simon, has been optimized for hardware implementations. Speck is an add–rotate–xor (ARX) cipher.
The NSA began working on the Simon and Speck ciphers in 2011. The agency anticipated some agencies in the US federal government would need a cipher that would operate well on a diverse collection of Internet of Things devices while maintaining an acceptable level of security.
Speck supports a variety of block and key sizes. A block is always two words, but the words may be 16, 24, 32, 48 or 64 bits in size. The corresponding key is 2, 3 or 4 words. The round function consists of two rotations, adding the right word to the left word, xoring the key into the left word, then xoring the left word into the right word. The number of rounds depends on the parameters selected, as follows:
The key schedule uses the same round function as the main block cipher.
The following is the designers' reference implementation, written in C, of the Speck variant with a 128-bit block size and key, where key = (K[1], K[0]). It is adapted from their IACR ePrint.
Note that this code computes the round keys (key schedule) on-demand. In practice, as with other block ciphers it is common for implementations to compute the round keys just once and cache them, rather than recomputing them for every block encrypted or decrypted. Although, as the authors point out, "Given that small code size was a major goal of the design, it made sense to reuse the round function for round key generation. This approach enables on-the-fly round key generation for microcontroller implementations, using just the round function code, very little ROM, and no RAM beyond what is required to hold the key and plaintext."
For 16-bit words (Speck32), the rotates are 7 bits right and 2 bits left; for all other word sizes, they are 8 and 3 as shown here.
If the key is more than 2 words long, there are 2 or 3 a values, which are used in rotation.
Speck (cipher)
Speck is part of a family of lightweight block ciphers publicly released by the National Security Agency (NSA) in June 2013. Speck has been optimized for performance in software implementations, while its sister algorithm, Simon, has been optimized for hardware implementations. Speck is an add–rotate–xor (ARX) cipher.
The NSA began working on the Simon and Speck ciphers in 2011. The agency anticipated some agencies in the US federal government would need a cipher that would operate well on a diverse collection of Internet of Things devices while maintaining an acceptable level of security.
Speck supports a variety of block and key sizes. A block is always two words, but the words may be 16, 24, 32, 48 or 64 bits in size. The corresponding key is 2, 3 or 4 words. The round function consists of two rotations, adding the right word to the left word, xoring the key into the left word, then xoring the left word into the right word. The number of rounds depends on the parameters selected, as follows:
The key schedule uses the same round function as the main block cipher.
The following is the designers' reference implementation, written in C, of the Speck variant with a 128-bit block size and key, where key = (K[1], K[0]). It is adapted from their IACR ePrint.
Note that this code computes the round keys (key schedule) on-demand. In practice, as with other block ciphers it is common for implementations to compute the round keys just once and cache them, rather than recomputing them for every block encrypted or decrypted. Although, as the authors point out, "Given that small code size was a major goal of the design, it made sense to reuse the round function for round key generation. This approach enables on-the-fly round key generation for microcontroller implementations, using just the round function code, very little ROM, and no RAM beyond what is required to hold the key and plaintext."
For 16-bit words (Speck32), the rotates are 7 bits right and 2 bits left; for all other word sizes, they are 8 and 3 as shown here.
If the key is more than 2 words long, there are 2 or 3 a values, which are used in rotation.
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