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// Copyright 2009 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 sha256 implements the SHA224 and SHA256 hash algorithms as defined
// in FIPS 180-4.
package sha256
import (
"crypto"
"encoding/binary"
"errors"
"hash"
)
func init() {
crypto.RegisterHash(crypto.SHA224, New224)
crypto.RegisterHash(crypto.SHA256, New)
}
// The size of a SHA256 checksum in bytes.
const Size = 32
// The size of a SHA224 checksum in bytes.
const Size224 = 28
// The blocksize of SHA256 and SHA224 in bytes.
const BlockSize = 64
const (
chunk = 64
init0 = 0x6A09E667
init1 = 0xBB67AE85
init2 = 0x3C6EF372
init3 = 0xA54FF53A
init4 = 0x510E527F
init5 = 0x9B05688C
init6 = 0x1F83D9AB
init7 = 0x5BE0CD19
init0_224 = 0xC1059ED8
init1_224 = 0x367CD507
init2_224 = 0x3070DD17
init3_224 = 0xF70E5939
init4_224 = 0xFFC00B31
init5_224 = 0x68581511
init6_224 = 0x64F98FA7
init7_224 = 0xBEFA4FA4
)
// digest represents the partial evaluation of a checksum.
type digest struct {
h [8]uint32
x [chunk]byte
nx int
len uint64
is224 bool // mark if this digest is SHA-224
}
const (
magic224 = "sha\x02"
magic256 = "sha\x03"
marshaledSize = len(magic256) + 8*4 + chunk + 8
)
func (d *digest) MarshalBinary() ([]byte, error) {
b := make([]byte, 0, marshaledSize)
if d.is224 {
b = append(b, magic224...)
} else {
b = append(b, magic256...)
}
b = appendUint32(b, d.h[0])
b = appendUint32(b, d.h[1])
b = appendUint32(b, d.h[2])
b = appendUint32(b, d.h[3])
b = appendUint32(b, d.h[4])
b = appendUint32(b, d.h[5])
b = appendUint32(b, d.h[6])
b = appendUint32(b, d.h[7])
b = append(b, d.x[:d.nx]...)
b = b[:len(b)+len(d.x)-int(d.nx)] // already zero
b = appendUint64(b, d.len)
return b, nil
}
func (d *digest) UnmarshalBinary(b []byte) error {
if len(b) < len(magic224) || (d.is224 && string(b[:len(magic224)]) != magic224) || (!d.is224 && string(b[:len(magic256)]) != magic256) {
return errors.New("crypto/sha256: invalid hash state identifier")
}
if len(b) != marshaledSize {
return errors.New("crypto/sha256: invalid hash state size")
}
b = b[len(magic224):]
b, d.h[0] = consumeUint32(b)
b, d.h[1] = consumeUint32(b)
b, d.h[2] = consumeUint32(b)
b, d.h[3] = consumeUint32(b)
b, d.h[4] = consumeUint32(b)
b, d.h[5] = consumeUint32(b)
b, d.h[6] = consumeUint32(b)
b, d.h[7] = consumeUint32(b)
b = b[copy(d.x[:], b):]
b, d.len = consumeUint64(b)
d.nx = int(d.len % chunk)
return nil
}
func appendUint64(b []byte, x uint64) []byte {
var a [8]byte
binary.BigEndian.PutUint64(a[:], x)
return append(b, a[:]...)
}
func appendUint32(b []byte, x uint32) []byte {
var a [4]byte
binary.BigEndian.PutUint32(a[:], x)
return append(b, a[:]...)
}
func consumeUint64(b []byte) ([]byte, uint64) {
_ = b[7]
x := uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 |
uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56
return b[8:], x
}
func consumeUint32(b []byte) ([]byte, uint32) {
_ = b[3]
x := uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24
return b[4:], x
}
func (d *digest) Reset() {
if !d.is224 {
d.h[0] = init0
d.h[1] = init1
d.h[2] = init2
d.h[3] = init3
d.h[4] = init4
d.h[5] = init5
d.h[6] = init6
d.h[7] = init7
} else {
d.h[0] = init0_224
d.h[1] = init1_224
d.h[2] = init2_224
d.h[3] = init3_224
d.h[4] = init4_224
d.h[5] = init5_224
d.h[6] = init6_224
d.h[7] = init7_224
}
d.nx = 0
d.len = 0
}
// New returns a new hash.Hash computing the SHA256 checksum. The Hash
// also implements encoding.BinaryMarshaler and
// encoding.BinaryUnmarshaler to marshal and unmarshal the internal
// state of the hash.
func New() hash.Hash {
d := new(digest)
d.Reset()
return d
}
// New224 returns a new hash.Hash computing the SHA224 checksum.
func New224() hash.Hash {
d := new(digest)
d.is224 = true
d.Reset()
return d
}
func (d *digest) Size() int {
if !d.is224 {
return Size
}
return Size224
}
func (d *digest) BlockSize() int { return BlockSize }
func (d *digest) Write(p []byte) (nn int, err error) {
nn = len(p)
d.len += uint64(nn)
if d.nx > 0 {
n := copy(d.x[d.nx:], p)
d.nx += n
if d.nx == chunk {
block(d, d.x[:])
d.nx = 0
}
p = p[n:]
}
if len(p) >= chunk {
n := len(p) &^ (chunk - 1)
block(d, p[:n])
p = p[n:]
}
if len(p) > 0 {
d.nx = copy(d.x[:], p)
}
return
}
func (d *digest) Sum(in []byte) []byte {
// Make a copy of d so that caller can keep writing and summing.
d0 := *d
hash := d0.checkSum()
if d0.is224 {
return append(in, hash[:Size224]...)
}
return append(in, hash[:]...)
}
func (d *digest) checkSum() [Size]byte {
len := d.len
// Padding. Add a 1 bit and 0 bits until 56 bytes mod 64.
var tmp [64]byte
tmp[0] = 0x80
if len%64 < 56 {
d.Write(tmp[0 : 56-len%64])
} else {
d.Write(tmp[0 : 64+56-len%64])
}
// Length in bits.
len <<= 3
binary.BigEndian.PutUint64(tmp[:], len)
d.Write(tmp[0:8])
if d.nx != 0 {
panic("d.nx != 0")
}
var digest [Size]byte
binary.BigEndian.PutUint32(digest[0:], d.h[0])
binary.BigEndian.PutUint32(digest[4:], d.h[1])
binary.BigEndian.PutUint32(digest[8:], d.h[2])
binary.BigEndian.PutUint32(digest[12:], d.h[3])
binary.BigEndian.PutUint32(digest[16:], d.h[4])
binary.BigEndian.PutUint32(digest[20:], d.h[5])
binary.BigEndian.PutUint32(digest[24:], d.h[6])
if !d.is224 {
binary.BigEndian.PutUint32(digest[28:], d.h[7])
}
return digest
}
// Sum256 returns the SHA256 checksum of the data.
func Sum256(data []byte) [Size]byte {
var d digest
d.Reset()
d.Write(data)
return d.checkSum()
}
// Sum224 returns the SHA224 checksum of the data.
func Sum224(data []byte) [Size224]byte {
var d digest
d.is224 = true
d.Reset()
d.Write(data)
sum := d.checkSum()
ap := (*[Size224]byte)(sum[:])
return *ap
}
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