sha3m

Documentation

Overview

Package sha3m implements the SHA-3 fixed-output-length hash functions with modifications for DeSo proof-of-work

Guidance

Security strengths

The SHA3-x (x equals 224, 256, 384, or 512) functions have a security strength against preimage attacks of x bits. Since they only produce "x" bits of output, their collision-resistance is only "x/2" bits.

The sponge construction

A sponge builds a pseudo-random function from a public pseudo-random permutation, by applying the permutation to a state of "rate + capacity" bytes, but hiding "capacity" of the bytes.

A sponge starts out with a zero state. To hash an input using a sponge, up to "rate" bytes of the input are XORed into the sponge's state. The sponge is then "full" and the permutation is applied to "empty" it. This process is repeated until all the input has been "absorbed". The input is then padded. The digest is "squeezed" from the sponge in the same way, except that output is copied out instead of input being XORed in.

A sponge is parameterized by its generic security strength, which is equal to half its capacity; capacity + rate is equal to the permutation's width. Since the KeccakF-1600 permutation is 1600 bits (200 bytes) wide, this means that the security strength of a sponge instance is equal to (1600 - bitrate) / 2.

The SHA-3 functions are "drop-in" replacements for the SHA-2 functions. They produce output of the same length, with the same security strengths against all attacks. This means, in particular, that SHA3-256 only has 128-bit collision resistance, because its output length is 32 bytes.

Index

• func New256() hash.Hash
• func Sum256(data []byte) (digest [32]byte)

Functions

func New256

func New256() hash.Hash

New256 creates a new SHA3-256 hash. Its generic security strength is 256 bits against preimage attacks, and 128 bits against collision attacks.

func Sum256

func Sum256(data []byte) (digest [32]byte)

Sum256 returns the SHA3-256 digest of the data.