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 re ...

which was created by Lars R. Knudsen.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 compression ...

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 compression ...

, respectively, however, shortly after the SMASH presentation at

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, 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 In cryptography, confusion and diffusion are two properties of the operation of a secure cipher identified by Claude Shannon in his 1945 classified report ''A Mathematical Theory of Cryptography'.'' These properties, when present, work to thwart ...

and variable rotations, details can be found here

Details

The

in SMASH are derived versions from the

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ones.

References

Cryptographic hash functions {{crypto-stub