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// Copyright 2016 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 blake2s implements the BLAKE2s hash algorithm defined by RFC 7693
// and the extendable output function (XOF) BLAKE2Xs.
//
// For a detailed specification of BLAKE2s see https://blake2.net/blake2.pdf
// and for BLAKE2Xs see https://blake2.net/blake2x.pdf
//
// If you aren't sure which function you need, use BLAKE2s (Sum256 or New256).
// If you need a secret-key MAC (message authentication code), use the New256
// function with a non-nil key.
//
// BLAKE2X is a construction to compute hash values larger than 32 bytes. It
// can produce hash values between 0 and 65535 bytes.
package blake2s // import "golang.org/x/crypto/blake2s"
import (
"encoding/binary"
"errors"
"hash"
)
const (
// The blocksize of BLAKE2s in bytes.
BlockSize = 64
// The hash size of BLAKE2s-256 in bytes.
Size = 32
// The hash size of BLAKE2s-128 in bytes.
Size128 = 16
)
var errKeySize = errors.New("blake2s: invalid key size")
var iv = [8]uint32{
0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19,
}
// Sum256 returns the BLAKE2s-256 checksum of the data.
func Sum256(data []byte) [Size]byte {
var sum [Size]byte
checkSum(&sum, Size, data)
return sum
}
// New256 returns a new hash.Hash computing the BLAKE2s-256 checksum. A non-nil
// key turns the hash into a MAC. The key must between zero and 32 bytes long.
func New256(key []byte) (hash.Hash, error) { return newDigest(Size, key) }
// New128 returns a new hash.Hash computing the BLAKE2s-128 checksum given a
// non-empty key. Note that a 128-bit digest is too small to be secure as a
// cryptographic hash and should only be used as a MAC, thus the key argument
// is not optional.
func New128(key []byte) (hash.Hash, error) {
if len(key) == 0 {
return nil, errors.New("blake2s: a key is required for a 128-bit hash")
}
return newDigest(Size128, key)
}
func newDigest(hashSize int, key []byte) (*digest, error) {
if len(key) > Size {
return nil, errKeySize
}
d := &digest{
size: hashSize,
keyLen: len(key),
}
copy(d.key[:], key)
d.Reset()
return d, nil
}
func checkSum(sum *[Size]byte, hashSize int, data []byte) {
var (
h [8]uint32
c [2]uint32
)
h = iv
h[0] ^= uint32(hashSize) | (1 << 16) | (1 << 24)
if length := len(data); length > BlockSize {
n := length &^ (BlockSize - 1)
if length == n {
n -= BlockSize
}
hashBlocks(&h, &c, 0, data[:n])
data = data[n:]
}
var block [BlockSize]byte
offset := copy(block[:], data)
remaining := uint32(BlockSize - offset)
if c[0] < remaining {
c[1]--
}
c[0] -= remaining
hashBlocks(&h, &c, 0xFFFFFFFF, block[:])
for i, v := range h {
binary.LittleEndian.PutUint32(sum[4*i:], v)
}
}
type digest struct {
h [8]uint32
c [2]uint32
size int
block [BlockSize]byte
offset int
key [BlockSize]byte
keyLen int
}
func (d *digest) BlockSize() int { return BlockSize }
func (d *digest) Size() int { return d.size }
func (d *digest) Reset() {
d.h = iv
d.h[0] ^= uint32(d.size) | (uint32(d.keyLen) << 8) | (1 << 16) | (1 << 24)
d.offset, d.c[0], d.c[1] = 0, 0, 0
if d.keyLen > 0 {
d.block = d.key
d.offset = BlockSize
}
}
func (d *digest) Write(p []byte) (n int, err error) {
n = len(p)
if d.offset > 0 {
remaining := BlockSize - d.offset
if n <= remaining {
d.offset += copy(d.block[d.offset:], p)
return
}
copy(d.block[d.offset:], p[:remaining])
hashBlocks(&d.h, &d.c, 0, d.block[:])
d.offset = 0
p = p[remaining:]
}
if length := len(p); length > BlockSize {
nn := length &^ (BlockSize - 1)
if length == nn {
nn -= BlockSize
}
hashBlocks(&d.h, &d.c, 0, p[:nn])
p = p[nn:]
}
d.offset += copy(d.block[:], p)
return
}
func (d *digest) Sum(sum []byte) []byte {
var hash [Size]byte
d.finalize(&hash)
return append(sum, hash[:d.size]...)
}
func (d *digest) finalize(hash *[Size]byte) {
var block [BlockSize]byte
h := d.h
c := d.c
copy(block[:], d.block[:d.offset])
remaining := uint32(BlockSize - d.offset)
if c[0] < remaining {
c[1]--
}
c[0] -= remaining
hashBlocks(&h, &c, 0xFFFFFFFF, block[:])
for i, v := range h {
binary.LittleEndian.PutUint32(hash[4*i:], v)
}
}
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