/
sc_sub.go
222 lines (206 loc) · 4.67 KB
/
sc_sub.go
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
219
220
221
222
package mnemonic
import (
"encoding/binary"
)
//
//nolint:lll
// This file is a Go port of the following code:
// https://github.com/monero-project/monero/blob/v0.18.2.2/src/crypto/crypto_ops_builder/ref10CommentedCombined/sc_sub.xmr.c
//
func load3(in []byte) int64 {
return int64(uint64(in[0]) | uint64(in[1])<<8 | uint64(in[2])<<16)
}
func load4(in []byte) int64 {
return int64(binary.LittleEndian.Uint32(in))
}
func scSub(a []byte, b []byte) []byte {
var s [32]byte // returned result
a0 := 2097151 & load3(a)
a1 := 2097151 & (load4(a[2:]) >> 5)
a2 := 2097151 & (load3(a[5:]) >> 2)
a3 := 2097151 & (load4(a[7:]) >> 7)
a4 := 2097151 & (load4(a[10:]) >> 4)
a5 := 2097151 & (load3(a[13:]) >> 1)
a6 := 2097151 & (load4(a[15:]) >> 6)
a7 := 2097151 & (load3(a[18:]) >> 3)
a8 := 2097151 & load3(a[21:])
a9 := 2097151 & (load4(a[23:]) >> 5)
a10 := 2097151 & (load3(a[26:]) >> 2)
a11 := load4(a[28:]) >> 7
b0 := 2097151 & load3(b)
b1 := 2097151 & (load4(b[2:]) >> 5)
b2 := 2097151 & (load3(b[5:]) >> 2)
b3 := 2097151 & (load4(b[7:]) >> 7)
b4 := 2097151 & (load4(b[10:]) >> 4)
b5 := 2097151 & (load3(b[13:]) >> 1)
b6 := 2097151 & (load4(b[15:]) >> 6)
b7 := 2097151 & (load3(b[18:]) >> 3)
b8 := 2097151 & load3(b[21:])
b9 := 2097151 & (load4(b[23:]) >> 5)
b10 := 2097151 & (load3(b[26:]) >> 2)
b11 := load4(b[28:]) >> 7
s0 := a0 - b0
s1 := a1 - b1
s2 := a2 - b2
s3 := a3 - b3
s4 := a4 - b4
s5 := a5 - b5
s6 := a6 - b6
s7 := a7 - b7
s8 := a8 - b8
s9 := a9 - b9
s10 := a10 - b10
s11 := a11 - b11
s12 := int64(0)
carry0 := (s0 + (1 << 20)) >> 21
s1 += carry0
s0 -= carry0 << 21
carry2 := (s2 + (1 << 20)) >> 21
s3 += carry2
s2 -= carry2 << 21
carry4 := (s4 + (1 << 20)) >> 21
s5 += carry4
s4 -= carry4 << 21
carry6 := (s6 + (1 << 20)) >> 21
s7 += carry6
s6 -= carry6 << 21
carry8 := (s8 + (1 << 20)) >> 21
s9 += carry8
s8 -= carry8 << 21
carry10 := (s10 + (1 << 20)) >> 21
s11 += carry10
s10 -= carry10 << 21
carry1 := (s1 + (1 << 20)) >> 21
s2 += carry1
s1 -= carry1 << 21
carry3 := (s3 + (1 << 20)) >> 21
s4 += carry3
s3 -= carry3 << 21
carry5 := (s5 + (1 << 20)) >> 21
s6 += carry5
s5 -= carry5 << 21
carry7 := (s7 + (1 << 20)) >> 21
s8 += carry7
s7 -= carry7 << 21
carry9 := (s9 + (1 << 20)) >> 21
s10 += carry9
s9 -= carry9 << 21
carry11 := (s11 + (1 << 20)) >> 21
s12 += carry11
s11 -= carry11 << 21
s0 += s12 * 666643
s1 += s12 * 470296
s2 += s12 * 654183
s3 -= s12 * 997805
s4 += s12 * 136657
s5 -= s12 * 683901
s12 = 0
carry0 = s0 >> 21
s1 += carry0
s0 -= carry0 << 21
carry1 = s1 >> 21
s2 += carry1
s1 -= carry1 << 21
carry2 = s2 >> 21
s3 += carry2
s2 -= carry2 << 21
carry3 = s3 >> 21
s4 += carry3
s3 -= carry3 << 21
carry4 = s4 >> 21
s5 += carry4
s4 -= carry4 << 21
carry5 = s5 >> 21
s6 += carry5
s5 -= carry5 << 21
carry6 = s6 >> 21
s7 += carry6
s6 -= carry6 << 21
carry7 = s7 >> 21
s8 += carry7
s7 -= carry7 << 21
carry8 = s8 >> 21
s9 += carry8
s8 -= carry8 << 21
carry9 = s9 >> 21
s10 += carry9
s9 -= carry9 << 21
carry10 = s10 >> 21
s11 += carry10
s10 -= carry10 << 21
carry11 = s11 >> 21
s12 += carry11
s11 -= carry11 << 21
s0 += s12 * 666643
s1 += s12 * 470296
s2 += s12 * 654183
s3 -= s12 * 997805
s4 += s12 * 136657
s5 -= s12 * 683901
carry0 = s0 >> 21
s1 += carry0
s0 -= carry0 << 21
carry1 = s1 >> 21
s2 += carry1
s1 -= carry1 << 21
carry2 = s2 >> 21
s3 += carry2
s2 -= carry2 << 21
carry3 = s3 >> 21
s4 += carry3
s3 -= carry3 << 21
carry4 = s4 >> 21
s5 += carry4
s4 -= carry4 << 21
carry5 = s5 >> 21
s6 += carry5
s5 -= carry5 << 21
carry6 = s6 >> 21
s7 += carry6
s6 -= carry6 << 21
carry7 = s7 >> 21
s8 += carry7
s7 -= carry7 << 21
carry8 = s8 >> 21
s9 += carry8
s8 -= carry8 << 21
carry9 = s9 >> 21
s10 += carry9
s9 -= carry9 << 21
carry10 = s10 >> 21
s11 += carry10
s10 -= carry10 << 21
s[0] = byte(s0 >> 0)
s[1] = byte(s0 >> 8)
s[2] = byte((s0 >> 16) | (s1 << 5))
s[3] = byte(s1 >> 3)
s[4] = byte(s1 >> 11)
s[5] = byte((s1 >> 19) | (s2 << 2))
s[6] = byte(s2 >> 6)
s[7] = byte((s2 >> 14) | (s3 << 7))
s[8] = byte(s3 >> 1)
s[9] = byte(s3 >> 9)
s[10] = byte((s3 >> 17) | (s4 << 4))
s[11] = byte(s4 >> 4)
s[12] = byte(s4 >> 12)
s[13] = byte((s4 >> 20) | (s5 << 1))
s[14] = byte(s5 >> 7)
s[15] = byte((s5 >> 15) | (s6 << 6))
s[16] = byte(s6 >> 2)
s[17] = byte(s6 >> 10)
s[18] = byte((s6 >> 18) | (s7 << 3))
s[19] = byte(s7 >> 5)
s[20] = byte(s7 >> 13)
s[21] = byte(s8 >> 0)
s[22] = byte(s8 >> 8)
s[23] = byte((s8 >> 16) | (s9 << 5))
s[24] = byte(s9 >> 3)
s[25] = byte(s9 >> 11)
s[26] = byte((s9 >> 19) | (s10 << 2))
s[27] = byte(s10 >> 6)
s[28] = byte((s10 >> 14) | (s11 << 7))
s[29] = byte(s11 >> 1)
s[30] = byte(s11 >> 9)
s[31] = byte(s11 >> 17)
return s[:]
}