176 lines
3.1 KiB
Go
176 lines
3.1 KiB
Go
// Copyright 2009 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 sha256 implements the SHA224 and SHA256 hash algorithms as defined
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// in FIPS 180-2.
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package sha256
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import (
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"crypto"
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"hash"
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)
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func init() {
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crypto.RegisterHash(crypto.SHA224, New224)
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crypto.RegisterHash(crypto.SHA256, New)
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}
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// The size of a SHA256 checksum in bytes.
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const Size = 32
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// The size of a SHA224 checksum in bytes.
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const Size224 = 28
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// The blocksize of SHA256 and SHA224 in bytes.
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const BlockSize = 64
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const (
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chunk = 64
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init0 = 0x6A09E667
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init1 = 0xBB67AE85
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init2 = 0x3C6EF372
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init3 = 0xA54FF53A
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init4 = 0x510E527F
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init5 = 0x9B05688C
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init6 = 0x1F83D9AB
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init7 = 0x5BE0CD19
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init0_224 = 0xC1059ED8
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init1_224 = 0x367CD507
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init2_224 = 0x3070DD17
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init3_224 = 0xF70E5939
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init4_224 = 0xFFC00B31
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init5_224 = 0x68581511
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init6_224 = 0x64F98FA7
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init7_224 = 0xBEFA4FA4
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)
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// digest represents the partial evaluation of a checksum.
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type digest struct {
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h [8]uint32
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x [chunk]byte
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nx int
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len uint64
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is224 bool // mark if this digest is SHA-224
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}
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func (d *digest) Reset() {
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if !d.is224 {
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d.h[0] = init0
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d.h[1] = init1
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d.h[2] = init2
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d.h[3] = init3
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d.h[4] = init4
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d.h[5] = init5
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d.h[6] = init6
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d.h[7] = init7
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} else {
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d.h[0] = init0_224
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d.h[1] = init1_224
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d.h[2] = init2_224
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d.h[3] = init3_224
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d.h[4] = init4_224
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d.h[5] = init5_224
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d.h[6] = init6_224
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d.h[7] = init7_224
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}
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d.nx = 0
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d.len = 0
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}
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// New returns a new hash.Hash computing the SHA256 checksum.
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func New() hash.Hash {
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d := new(digest)
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d.Reset()
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return d
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}
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// New224 returns a new hash.Hash computing the SHA224 checksum.
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func New224() hash.Hash {
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d := new(digest)
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d.is224 = true
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d.Reset()
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return d
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}
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func (d *digest) Size() int {
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if !d.is224 {
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return Size
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}
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return Size224
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}
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func (d *digest) BlockSize() int { return BlockSize }
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func (d *digest) Write(p []byte) (nn int, err error) {
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nn = len(p)
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d.len += uint64(nn)
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if d.nx > 0 {
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n := len(p)
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if n > chunk-d.nx {
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n = chunk - d.nx
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}
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for i := 0; i < n; i++ {
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d.x[d.nx+i] = p[i]
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}
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d.nx += n
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if d.nx == chunk {
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block(d, d.x[0:])
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d.nx = 0
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}
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p = p[n:]
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}
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if len(p) >= chunk {
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n := len(p) &^ (chunk - 1)
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block(d, p[:n])
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p = p[n:]
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}
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if len(p) > 0 {
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d.nx = copy(d.x[:], p)
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}
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return
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}
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func (d0 *digest) Sum(in []byte) []byte {
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// Make a copy of d0 so that caller can keep writing and summing.
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d := *d0
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// Padding. Add a 1 bit and 0 bits until 56 bytes mod 64.
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len := d.len
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var tmp [64]byte
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tmp[0] = 0x80
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if len%64 < 56 {
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d.Write(tmp[0 : 56-len%64])
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} else {
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d.Write(tmp[0 : 64+56-len%64])
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}
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// Length in bits.
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len <<= 3
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for i := uint(0); i < 8; i++ {
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tmp[i] = byte(len >> (56 - 8*i))
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}
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d.Write(tmp[0:8])
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if d.nx != 0 {
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panic("d.nx != 0")
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}
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h := d.h[:]
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size := Size
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if d.is224 {
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h = d.h[:7]
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size = Size224
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}
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var digest [Size]byte
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for i, s := range h {
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digest[i*4] = byte(s >> 24)
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digest[i*4+1] = byte(s >> 16)
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digest[i*4+2] = byte(s >> 8)
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digest[i*4+3] = byte(s)
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}
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return append(in, digest[:size]...)
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}
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