/usr/share/gocode/src/github.com/btcsuite/fastsha256/sha256.go is in golang-github-btcsuite-fastsha256-dev 0.0~git20160815.0.637e656-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 | // 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 fastsha256 implements the SHA224 and SHA256 hash algorithms as defined
// in FIPS 180-4.
package fastsha256
import (
"crypto"
"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
}
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.
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
for i := uint(0); i < 8; i++ {
tmp[i] = byte(len >> (56 - 8*i))
}
d.Write(tmp[0:8])
if d.nx != 0 {
panic("d.nx != 0")
}
h := d.h[:]
if d.is224 {
h = d.h[:7]
}
var digest [Size]byte
for i, s := range h {
digest[i*4] = byte(s >> 24)
digest[i*4+1] = byte(s >> 16)
digest[i*4+2] = byte(s >> 8)
digest[i*4+3] = byte(s)
}
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) (sum224 [Size224]byte) {
var d digest
d.is224 = true
d.Reset()
d.Write(data)
sum := d.checkSum()
copy(sum224[:], sum[:Size224])
return
}
// MidState256 returns the internal hashing state after hashing the first chunk
// (BlockSize) of the data. This implemenation does not provide any mechanism
// to initialize the internal hashing state, so this information can't be used
// to skip hashing the first chunk on subsequent calls, but it is exposed so
// sophisticated callers can make use of it.
func MidState256(data []byte) [Size]byte {
if len(data) > BlockSize {
data = data[:BlockSize]
}
var d digest
d.Reset()
d.Write(data)
var midState [Size]byte
for i, s := range d.h {
midState[i*4] = byte(s >> 24)
midState[i*4+1] = byte(s >> 16)
midState[i*4+2] = byte(s >> 8)
midState[i*4+3] = byte(s)
}
return midState
}
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