hash

Documentation

Overview

Package hash provides an interface that hash functions (as gadget) should implement.

Index

• func Register(name string, builder func(api frontend.API) (FieldHasher, error))
• type BinaryFixedLengthHasher
• type BinaryHasher
• type FieldHasher
  • func GetFieldHasher(name string, api frontend.API) (FieldHasher, error)

Functions

func Register

func Register(name string, builder func(api frontend.API) (FieldHasher, error))

Types

type BinaryFixedLengthHasher

type BinaryFixedLengthHasher interface {
	BinaryHasher
	// FixedLengthSum returns digest of the first length bytes.
	FixedLengthSum(length frontend.Variable) []uints.U8
}

BinaryFixedLengthHasher is like BinaryHasher, but assumes the length of the input is not full length as defined during compile time. This allows to compute digest of variable-length input, unlike BinaryHasher which assumes the length of the input is the total number of bytes written.

type BinaryHasher

type BinaryHasher interface {
	// Sum finalises the current hash and returns the digest.
	Sum() []uints.U8

	// Write writes more bytes into the current hash state.
	Write([]uints.U8)

	// Size returns the number of bytes this hash function returns in a call to
	// [BinaryHasher.Sum].
	Size() int
}

BinaryHasher hashes inputs into a short digest. It takes as inputs bytes and outputs byte array whose length depends on the underlying hash function. For SNARK-native hash functions use FieldHasher.

type FieldHasher

type FieldHasher interface {
	// Sum computes the hash of the internal state of the hash function.
	Sum() frontend.Variable

	// Write populate the internal state of the hash function with data. The inputs are native field elements.
	Write(data ...frontend.Variable)

	// Reset empty the internal state and put the intermediate state to zero.
	Reset()
}

FieldHasher hashes inputs into a short digest. This interface mocks BinaryHasher, but is more suitable in-circuit by assuming the inputs are scalar field elements and outputs digest as a field element. Such hash functions are for examle Poseidon, MiMC etc.

func GetFieldHasher

func GetFieldHasher(name string, api frontend.API) (FieldHasher, error)