src/crypto/sha1/sha1.go - go - Git at Google

 // 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 sha1 implements the SHA-1 hash algorithm as defined in RFC 3174.
 //
 // SHA-1 is cryptographically broken and should not be used for secure
 // applications.
 package sha1

 import (
 	"crypto"
 	"errors"
 	"hash"
 )

 func init() {
 	crypto.RegisterHash(crypto.SHA1, New)
 }

 // The size of a SHA-1 checksum in bytes.
 const Size = 20

 // The blocksize of SHA-1 in bytes.
 const BlockSize = 64

 const (
 	chunk = 64
 	init0 = 0x67452301
 	init1 = 0xEFCDAB89
 	init2 = 0x98BADCFE
 	init3 = 0x10325476
 	init4 = 0xC3D2E1F0
 )

 // digest represents the partial evaluation of a checksum.
 type digest struct {
 	h   [5]uint32
 	x   [chunk]byte
 	nx  int
 	len uint64
 }

 const (
 	magic         = "sha\x01"
 	marshaledSize = len(magic) + 5*4 + chunk + 8
 )

 func (d *digest) MarshalBinary() ([]byte, error) {
 	b := make([]byte, 0, marshaledSize)
 	b = append(b, magic...)
 	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 = 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(magic) || string(b[:len(magic)]) != magic {
 		return errors.New("crypto/sha1: invalid hash state identifier")
 	}
 	if len(b) != marshaledSize {
 		return errors.New("crypto/sha1: invalid hash state size")
 	}
 	b = b[len(magic):]
 	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 = 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
 	putUint64(a[:], x)
 	return append(b, a[:]...)
 }

 func appendUint32(b []byte, x uint32) []byte {
 	var a [4]byte
 	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() {
 	d.h[0] = init0
 	d.h[1] = init1
 	d.h[2] = init2
 	d.h[3] = init3
 	d.h[4] = init4
 	d.nx = 0
 	d.len = 0
 }

 // New returns a new hash.Hash computing the SHA1 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
 }

 func (d *digest) Size() int { return Size }

 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()
 	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
 	putUint64(tmp[:], len)
 	d.Write(tmp[0:8])

 	if d.nx != 0 {
 		panic("d.nx != 0")
 	}

 	var digest [Size]byte

 	putUint32(digest[0:], d.h[0])
 	putUint32(digest[4:], d.h[1])
 	putUint32(digest[8:], d.h[2])
 	putUint32(digest[12:], d.h[3])
 	putUint32(digest[16:], d.h[4])

 	return digest
 }

 // ConstantTimeSum computes the same result of Sum() but in constant time
 func (d *digest) ConstantTimeSum(in []byte) []byte {
 	d0 := *d
 	hash := d0.constSum()
 	return append(in, hash[:]...)
 }

 func (d *digest) constSum() [Size]byte {
 	var length [8]byte
 	l := d.len << 3
 	for i := uint(0); i < 8; i++ {
 		length[i] = byte(l >> (56 - 8*i))
 	}

 	nx := byte(d.nx)
 	t := nx - 56                 // if nx < 56 then the MSB of t is one
 	mask1b := byte(int8(t) >> 7) // mask1b is 0xFF iff one block is enough

 	separator := byte(0x80) // gets reset to 0x00 once used
 	for i := byte(0); i < chunk; i++ {
 		mask := byte(int8(i-nx) >> 7) // 0x00 after the end of data

 		// if we reached the end of the data, replace with 0x80 or 0x00
 		d.x[i] = (^mask & separator) | (mask & d.x[i])

 		// zero the separator once used
 		separator &= mask

 		if i >= 56 {
 			// we might have to write the length here if all fit in one block
 			d.x[i] |= mask1b & length[i-56]
 		}
 	}

 	// compress, and only keep the digest if all fit in one block
 	block(d, d.x[:])

 	var digest [Size]byte
 	for i, s := range d.h {
 		digest[i*4] = mask1b & byte(s>>24)
 		digest[i*4+1] = mask1b & byte(s>>16)
 		digest[i*4+2] = mask1b & byte(s>>8)
 		digest[i*4+3] = mask1b & byte(s)
 	}

 	for i := byte(0); i < chunk; i++ {
 		// second block, it's always past the end of data, might start with 0x80
 		if i < 56 {
 			d.x[i] = separator
 			separator = 0
 		} else {
 			d.x[i] = length[i-56]
 		}
 	}

 	// compress, and only keep the digest if we actually needed the second block
 	block(d, d.x[:])

 	for i, s := range d.h {
 		digest[i*4] |= ^mask1b & byte(s>>24)
 		digest[i*4+1] |= ^mask1b & byte(s>>16)
 		digest[i*4+2] |= ^mask1b & byte(s>>8)
 		digest[i*4+3] |= ^mask1b & byte(s)
 	}

 	return digest
 }

 // Sum returns the SHA-1 checksum of the data.
 func Sum(data []byte) [Size]byte {
 	var d digest
 	d.Reset()
 	d.Write(data)
 	return d.checkSum()
 }

 func putUint64(x []byte, s uint64) {
 	_ = x[7]
 	x[0] = byte(s >> 56)
 	x[1] = byte(s >> 48)
 	x[2] = byte(s >> 40)
 	x[3] = byte(s >> 32)
 	x[4] = byte(s >> 24)
 	x[5] = byte(s >> 16)
 	x[6] = byte(s >> 8)
 	x[7] = byte(s)
 }

 func putUint32(x []byte, s uint32) {
 	_ = x[3]
 	x[0] = byte(s >> 24)
 	x[1] = byte(s >> 16)
 	x[2] = byte(s >> 8)
 	x[3] = byte(s)
 }
	// 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 sha1 implements the SHA-1 hash algorithm as defined in RFC 3174.
	//
	// SHA-1 is cryptographically broken and should not be used for secure
	// applications.
	package sha1

	import (
	"crypto"
	"errors"
	"hash"
	)

	func init() {
	crypto.RegisterHash(crypto.SHA1, New)
	}

	// The size of a SHA-1 checksum in bytes.
	const Size = 20

	// The blocksize of SHA-1 in bytes.
	const BlockSize = 64

	const (
	chunk = 64
	init0 = 0x67452301
	init1 = 0xEFCDAB89
	init2 = 0x98BADCFE
	init3 = 0x10325476
	init4 = 0xC3D2E1F0
	)

	// digest represents the partial evaluation of a checksum.
	type digest struct {
	h [5]uint32
	x [chunk]byte
	nx int
	len uint64
	}

	const (
	magic = "sha\x01"
	marshaledSize = len(magic) + 5*4 + chunk + 8
	)

	func (d *digest) MarshalBinary() ([]byte, error) {
	b := make([]byte, 0, marshaledSize)
	b = append(b, magic...)
	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 = 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(magic) \|\| string(b[:len(magic)]) != magic {
	return errors.New("crypto/sha1: invalid hash state identifier")
	}
	if len(b) != marshaledSize {
	return errors.New("crypto/sha1: invalid hash state size")
	}
	b = b[len(magic):]
	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 = 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
	putUint64(a[:], x)
	return append(b, a[:]...)
	}

	func appendUint32(b []byte, x uint32) []byte {
	var a [4]byte
	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() {
	d.h[0] = init0
	d.h[1] = init1
	d.h[2] = init2
	d.h[3] = init3
	d.h[4] = init4
	d.nx = 0
	d.len = 0
	}

	// New returns a new hash.Hash computing the SHA1 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
	}

	func (d *digest) Size() int { return Size }

	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()
	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
	putUint64(tmp[:], len)
	d.Write(tmp[0:8])

	if d.nx != 0 {
	panic("d.nx != 0")
	}

	var digest [Size]byte

	putUint32(digest[0:], d.h[0])
	putUint32(digest[4:], d.h[1])
	putUint32(digest[8:], d.h[2])
	putUint32(digest[12:], d.h[3])
	putUint32(digest[16:], d.h[4])

	return digest
	}

	// ConstantTimeSum computes the same result of Sum() but in constant time
	func (d *digest) ConstantTimeSum(in []byte) []byte {
	d0 := *d
	hash := d0.constSum()
	return append(in, hash[:]...)
	}

	func (d *digest) constSum() [Size]byte {
	var length [8]byte
	l := d.len << 3
	for i := uint(0); i < 8; i++ {
	length[i] = byte(l >> (56 - 8*i))
	}

	nx := byte(d.nx)
	t := nx - 56 // if nx < 56 then the MSB of t is one
	mask1b := byte(int8(t) >> 7) // mask1b is 0xFF iff one block is enough

	separator := byte(0x80) // gets reset to 0x00 once used
	for i := byte(0); i < chunk; i++ {
	mask := byte(int8(i-nx) >> 7) // 0x00 after the end of data

	// if we reached the end of the data, replace with 0x80 or 0x00
	d.x[i] = (^mask & separator) \| (mask & d.x[i])

	// zero the separator once used
	separator &= mask

	if i >= 56 {
	// we might have to write the length here if all fit in one block
	d.x[i] \|= mask1b & length[i-56]
	}
	}

	// compress, and only keep the digest if all fit in one block
	block(d, d.x[:])

	var digest [Size]byte
	for i, s := range d.h {
	digest[i*4] = mask1b & byte(s>>24)
	digest[i*4+1] = mask1b & byte(s>>16)
	digest[i*4+2] = mask1b & byte(s>>8)
	digest[i*4+3] = mask1b & byte(s)
	}

	for i := byte(0); i < chunk; i++ {
	// second block, it's always past the end of data, might start with 0x80
	if i < 56 {
	d.x[i] = separator
	separator = 0
	} else {
	d.x[i] = length[i-56]
	}
	}

	// compress, and only keep the digest if we actually needed the second block
	block(d, d.x[:])

	for i, s := range d.h {
	digest[i*4] \|= ^mask1b & byte(s>>24)
	digest[i*4+1] \|= ^mask1b & byte(s>>16)
	digest[i*4+2] \|= ^mask1b & byte(s>>8)
	digest[i*4+3] \|= ^mask1b & byte(s)
	}

	return digest
	}

	// Sum returns the SHA-1 checksum of the data.
	func Sum(data []byte) [Size]byte {
	var d digest
	d.Reset()
	d.Write(data)
	return d.checkSum()
	}

	func putUint64(x []byte, s uint64) {
	_ = x[7]
	x[0] = byte(s >> 56)
	x[1] = byte(s >> 48)
	x[2] = byte(s >> 40)
	x[3] = byte(s >> 32)
	x[4] = byte(s >> 24)
	x[5] = byte(s >> 16)
	x[6] = byte(s >> 8)
	x[7] = byte(s)
	}

	func putUint32(x []byte, s uint32) {
	_ = x[3]
	x[0] = byte(s >> 24)
	x[1] = byte(s >> 16)
	x[2] = byte(s >> 8)
	x[3] = byte(s)
	}