SMASH is a

cryptographic hash function A cryptographic hash function (CHF) is a hash algorithm (a map of an arbitrary binary string to a binary string with fixed size of n bits) that has special properties desirable for cryptography: * the probability of a particular n-bit output ...

which was created by

Lars R. Knudsen Lars Ramkilde Knudsen (born 21 February 1962) is a Danish researcher in cryptography, particularly interested in the design and analysis of block ciphers, hash functions and message authentication codes (MACs). Academic After some early work i ...

.Knudsen, Lars R.
SMASH - A Cryptographic Hash Function
Accessed 23 November 2009 SMASH comes in two versions: 256-bit and 512-bit. Each version was supposed to rival

SHA-256 SHA-2 (Secure Hash Algorithm 2) is a set of cryptographic hash functions designed by the United States National Security Agency (NSA) and first published in 2001. They are built using the Merkle–Damgård construction, from a one-way compressi ...

and

SHA-512 SHA-2 (Secure Hash Algorithm 2) is a set of cryptographic hash functions designed by the United States National Security Agency (NSA) and first published in 2001. They are built using the Merkle–Damgård construction, from a one-way compressi ...

, respectively, however, shortly after the SMASH presentation at FSE 2005, an attack vector against SMASH was discovered which left the hash broken.

Specifications

The message length was limited to less than 2¹²⁸ for SMASH-256 and 2²⁵⁶ for SMASH-512.

Definition

Input: 256/512-bit message blocks

m_1, m_2, ... ,m_t

and

\theta \in GF(2^n)

h_0 = f(iv) \oplus iv

h_i = h(h_,m_i) = f(h_\oplus m_i)  \oplus m_i \oplus \theta m_i

h_ = f(h_t) \oplus h_t

The function f is a complex compression function consisting of H-Rounds and L-Rounds using

S-boxes In cryptography, an S-box (substitution-box) is a basic component of symmetric key algorithms which performs substitution. In block ciphers, they are typically used to obscure the relationship between the key and the ciphertext, thus ensuring Shan ...

, linear diffusion and variable rotations, details can be found here

Details

The

in SMASH are derived versions from the

Serpent Serpent or The Serpent may refer to: * Snake, a carnivorous reptile of the suborder Serpentes Mythology and religion * Sea serpent, a monstrous ocean creature * Serpent (symbolism), the snake in religious rites and mythological contexts * Serp ...

ones.

References

Cryptographic hash functions {{crypto-stub