161 lines
3.1 KiB
Go
161 lines
3.1 KiB
Go
// Copyright 2016 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package blake2s implements the BLAKE2s hash algorithm as
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// defined in RFC 7693.
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package blake2s
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import (
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"encoding/binary"
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"errors"
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"hash"
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)
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const (
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// The blocksize of BLAKE2s in bytes.
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BlockSize = 64
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// The hash size of BLAKE2s-256 in bytes.
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Size = 32
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)
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var errKeySize = errors.New("blake2s: invalid key size")
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var iv = [8]uint32{
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0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
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0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19,
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}
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// Sum256 returns the BLAKE2s-256 checksum of the data.
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func Sum256(data []byte) [Size]byte {
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var sum [Size]byte
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checkSum(&sum, Size, data)
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return sum
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}
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// New256 returns a new hash.Hash computing the BLAKE2s-256 checksum. A non-nil
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// key turns the hash into a MAC. The key must between zero and 32 bytes long.
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func New256(key []byte) (hash.Hash, error) { return newDigest(Size, key) }
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func newDigest(hashSize int, key []byte) (*digest, error) {
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if len(key) > Size {
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return nil, errKeySize
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}
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d := &digest{
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size: hashSize,
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keyLen: len(key),
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}
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copy(d.key[:], key)
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d.Reset()
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return d, nil
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}
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func checkSum(sum *[Size]byte, hashSize int, data []byte) {
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var (
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h [8]uint32
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c [2]uint32
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)
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h = iv
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h[0] ^= uint32(hashSize) | (1 << 16) | (1 << 24)
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if length := len(data); length > BlockSize {
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n := length &^ (BlockSize - 1)
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if length == n {
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n -= BlockSize
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}
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hashBlocks(&h, &c, 0, data[:n])
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data = data[n:]
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}
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var block [BlockSize]byte
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offset := copy(block[:], data)
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remaining := uint32(BlockSize - offset)
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if c[0] < remaining {
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c[1]--
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}
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c[0] -= remaining
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hashBlocks(&h, &c, 0xFFFFFFFF, block[:])
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for i, v := range h {
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binary.LittleEndian.PutUint32(sum[4*i:], v)
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}
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}
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type digest struct {
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h [8]uint32
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c [2]uint32
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size int
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block [BlockSize]byte
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offset int
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key [BlockSize]byte
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keyLen int
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}
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func (d *digest) BlockSize() int { return BlockSize }
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func (d *digest) Size() int { return d.size }
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func (d *digest) Reset() {
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d.h = iv
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d.h[0] ^= uint32(d.size) | (uint32(d.keyLen) << 8) | (1 << 16) | (1 << 24)
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d.offset, d.c[0], d.c[1] = 0, 0, 0
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if d.keyLen > 0 {
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d.block = d.key
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d.offset = BlockSize
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}
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}
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func (d *digest) Write(p []byte) (n int, err error) {
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n = len(p)
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if d.offset > 0 {
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remaining := BlockSize - d.offset
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if n <= remaining {
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d.offset += copy(d.block[d.offset:], p)
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return
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}
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copy(d.block[d.offset:], p[:remaining])
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hashBlocks(&d.h, &d.c, 0, d.block[:])
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d.offset = 0
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p = p[remaining:]
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}
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if length := len(p); length > BlockSize {
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nn := length &^ (BlockSize - 1)
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if length == nn {
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nn -= BlockSize
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}
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hashBlocks(&d.h, &d.c, 0, p[:nn])
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p = p[nn:]
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}
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d.offset += copy(d.block[:], p)
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return
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}
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func (d *digest) Sum(b []byte) []byte {
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var block [BlockSize]byte
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h := d.h
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c := d.c
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copy(block[:], d.block[:d.offset])
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remaining := uint32(BlockSize - d.offset)
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if c[0] < remaining {
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c[1]--
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}
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c[0] -= remaining
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hashBlocks(&h, &c, 0xFFFFFFFF, block[:])
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var sum [Size]byte
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for i, v := range h {
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binary.LittleEndian.PutUint32(sum[4*i:], v)
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}
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return append(b, sum[:d.size]...)
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}
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