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
|
// Copyright © 2022 siddharth <s@ricketyspace.net>
// SPDX-License-Identifier: ISC
package lib
// SHA-256 implementation.
// Reference https://csrc.nist.gov/publications/detail/fips/180/4/final
type Sha256 struct {
hvs []uint32
Msg []byte
MsgLen int
}
// SHA-256 Constants
var sha256K []uint32 = []uint32{
0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2,
}
// SHA-256 initial hash values.
var sha256HashValues []uint32 = []uint32{
0x6a09e667,
0xbb67ae85,
0x3c6ef372,
0xa54ff53a,
0x510e527f,
0x9b05688c,
0x1f83d9ab,
0x5be0cd19,
}
// Ch(x,y,z) function.
func sha256FCh(x, y, z uint32) uint32 {
return (x & y) ^ (^x & z)
}
// Maj(x,y,z) function.
func sha256FMaj(x, y, z uint32) uint32 {
return (x & y) ^ (x & z) ^ (y & z)
}
// Σ0(x) function.
func sha256FΣ0(x uint32) uint32 {
return shaRotr(x, 2) ^ shaRotr(x, 13) ^ shaRotr(x, 22)
}
// Σ1(x) function.
func sha256FΣ1(x uint32) uint32 {
return shaRotr(x, 6) ^ shaRotr(x, 11) ^ shaRotr(x, 25)
}
// σ0(x) function.
func sha256Fσ0(x uint32) uint32 {
return shaRotr(x, 7) ^ shaRotr(x, 18) ^ shaShr(x, 3)
}
// σ1(x) function.
func sha256Fσ1(x uint32) uint32 {
return shaRotr(x, 17) ^ shaRotr(x, 19) ^ shaShr(x, 10)
}
// Returns the message schedule W_t for a message block `mb`
// The message schedule has 64 32-bit words.
func sha256MessageSchedule(mb []uint32) []uint32 {
// Message schedule.
w := make([]uint32, 0)
// Generate message schedule.
for t := 0; t < 64; t++ {
if t <= 15 {
w = append(w, mb[t])
} else {
w = append(w, shaAdd(
sha256Fσ1(w[t-2]),
w[t-7],
sha256Fσ0(w[t-15]),
w[t-16],
))
}
}
return w
}
func (s *Sha256) Init(hvs []uint32) {
// Set initial hash values.
h := make([]uint32, 8)
if len(hvs) == 8 {
copy(h, hvs)
s.hvs = h
} else {
copy(h, sha256HashValues)
s.hvs = h
}
}
func (s *Sha256) Message(m []byte) {
s.Msg = m
s.MsgLen = len(m)
}
// SHA-256 - Pad message such that its length is a multiple of 512.
func (s *Sha256) Pad() []byte {
// Initialize padded message.
pm := make([]byte, len(s.Msg))
copy(pm, s.Msg)
// Add padding.
pm = append(pm, MDPadding(s.MsgLen)...)
return pm
}
func (s *Sha256) Hash() []byte {
// Pad message.
pm := s.Pad()
// Break int message blocks.
mbs := shaMessageBlocks(pm)
// Initialize hash values.
hvs := make([]uint32, 8)
copy(hvs, s.hvs) // Initial hash values.
// Process each message block.
for _, mb := range mbs {
// Get message schedule.
w := sha256MessageSchedule(mb)
// Initialize working variables.
a := hvs[0]
b := hvs[1]
c := hvs[2]
d := hvs[3]
e := hvs[4]
f := hvs[5]
g := hvs[6]
h := hvs[7]
for t := 0; t <= 63; t++ {
t1 := shaAdd(
h,
sha256FΣ1(e),
sha256FCh(e, f, g),
sha256K[t],
w[t],
)
t2 := shaAdd(sha256FΣ0(a), sha256FMaj(a, b, c))
h = g
g = f
f = e
e = shaAdd(d, t1)
d = c
c = b
b = a
a = shaAdd(t1, t2)
}
// Compute intermediate hash values.
hvs[0] = shaAdd(a, hvs[0])
hvs[1] = shaAdd(b, hvs[1])
hvs[2] = shaAdd(c, hvs[2])
hvs[3] = shaAdd(d, hvs[3])
hvs[4] = shaAdd(e, hvs[4])
hvs[5] = shaAdd(f, hvs[5])
hvs[6] = shaAdd(g, hvs[6])
hvs[7] = shaAdd(h, hvs[7])
}
// Slurp sha256 digest from hash values.
d := make([]byte, 0) // sha256 digest
for i := 0; i < 8; i++ {
// Break 32-bit hash value into 4 bytes.
hb := make([]byte, 4)
for j := 3; j >= 0; j-- {
// Get last 8 bits.
hb[j] = byte(hvs[i] & 0xFF)
// Get rid of last 8 bits.
hvs[i] = hvs[i] >> 8
}
d = append(d, hb...)
}
return d
}
|
