// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fips140

import "io"

// Hash is the common interface implemented by all hash functions. It is a copy
// of [hash.Hash] from the standard library, to avoid depending on security
// definitions from outside of the module.
type Hash interface {
	// Write (via the embedded io.Writer interface) adds more data to the
	// running hash. It never returns an error.
	io.Writer

	// Sum appends the current hash to b and returns the resulting slice.
	// It does not change the underlying hash state.
	Sum(b []byte) []byte

	// Reset resets the Hash to its initial state.
	Reset()

	// Size returns the number of bytes Sum will return.
	Size() int

	// BlockSize returns the hash's underlying block size.
	// The Write method must be able to accept any amount
	// of data, but it may operate more efficiently if all writes
	// are a multiple of the block size.
	BlockSize() int
}