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
|
/*
* Ed25519
* (C) 2017 Ribose Inc
*
* Based on the public domain code from SUPERCOP ref10 by
* Peter Schwabe, Daniel J. Bernstein, Niels Duif, Tanja Lange, Bo-Yin Yang
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/internal/ed25519_internal.h>
namespace Botan {
/*
Input:
s[0]+256*s[1]+...+256^63*s[63] = s
Output:
s[0]+256*s[1]+...+256^31*s[31] = s mod l
where l = 2^252 + 27742317777372353535851937790883648493.
Overwrites s in place.
*/
void sc_reduce(uint8_t* s)
{
const uint32_t MASK = 0x1fffff;
int64_t s0 = MASK & load_3(s);
int64_t s1 = MASK & (load_4(s + 2) >> 5);
int64_t s2 = MASK & (load_3(s + 5) >> 2);
int64_t s3 = MASK & (load_4(s + 7) >> 7);
int64_t s4 = MASK & (load_4(s + 10) >> 4);
int64_t s5 = MASK & (load_3(s + 13) >> 1);
int64_t s6 = MASK & (load_4(s + 15) >> 6);
int64_t s7 = MASK & (load_3(s + 18) >> 3);
int64_t s8 = MASK & load_3(s + 21);
int64_t s9 = MASK & (load_4(s + 23) >> 5);
int64_t s10 = MASK & (load_3(s + 26) >> 2);
int64_t s11 = MASK & (load_4(s + 28) >> 7);
int64_t s12 = MASK & (load_4(s + 31) >> 4);
int64_t s13 = MASK & (load_3(s + 34) >> 1);
int64_t s14 = MASK & (load_4(s + 36) >> 6);
int64_t s15 = MASK & (load_3(s + 39) >> 3);
int64_t s16 = MASK & load_3(s + 42);
int64_t s17 = MASK & (load_4(s + 44) >> 5);
int64_t s18 = MASK & (load_3(s + 47) >> 2);
int64_t s19 = MASK & (load_4(s + 49) >> 7);
int64_t s20 = MASK & (load_4(s + 52) >> 4);
int64_t s21 = MASK & (load_3(s + 55) >> 1);
int64_t s22 = MASK & (load_4(s + 57) >> 6);
int64_t s23 = (load_4(s + 60) >> 3);
redc_mul(s11, s12, s13, s14, s15, s16, s23);
redc_mul(s10, s11, s12, s13, s14, s15, s22);
redc_mul( s9, s10, s11, s12, s13, s14, s21);
redc_mul( s8, s9, s10, s11, s12, s13, s20);
redc_mul( s7, s8, s9, s10, s11, s12, s19);
redc_mul( s6, s7, s8, s9, s10, s11, s18);
carry<21>(s6, s7);
carry<21>(s8, s9);
carry<21>(s10, s11);
carry<21>(s12, s13);
carry<21>(s14, s15);
carry<21>(s16, s17);
carry<21>(s7, s8);
carry<21>(s9, s10);
carry<21>(s11, s12);
carry<21>(s13, s14);
carry<21>(s15, s16);
redc_mul(s5, s6, s7, s8, s9, s10, s17);
redc_mul(s4, s5, s6, s7, s8, s9, s16);
redc_mul(s3, s4, s5, s6, s7, s8, s15);
redc_mul(s2, s3, s4, s5, s6, s7, s14);
redc_mul(s1, s2, s3, s4, s5, s6, s13);
redc_mul(s0, s1, s2, s3, s4, s5, s12);
carry<21>(s0, s1);
carry<21>(s2, s3);
carry<21>(s4, s5);
carry<21>(s6, s7);
carry<21>(s8, s9);
carry<21>(s10, s11);
carry<21>(s1, s2);
carry<21>(s3, s4);
carry<21>(s5, s6);
carry<21>(s7, s8);
carry<21>(s9, s10);
carry<21>(s11, s12);
redc_mul(s0, s1, s2, s3, s4, s5, s12);
carry0<21>(s0, s1);
carry0<21>(s1, s2);
carry0<21>(s2, s3);
carry0<21>(s3, s4);
carry0<21>(s4, s5);
carry0<21>(s5, s6);
carry0<21>(s6, s7);
carry0<21>(s7, s8);
carry0<21>(s8, s9);
carry0<21>(s9, s10);
carry0<21>(s10, s11);
carry0<21>(s11, s12);
redc_mul(s0, s1, s2, s3, s4, s5, s12);
carry0<21>(s0, s1);
carry0<21>(s1, s2);
carry0<21>(s2, s3);
carry0<21>(s3, s4);
carry0<21>(s4, s5);
carry0<21>(s5, s6);
carry0<21>(s6, s7);
carry0<21>(s7, s8);
carry0<21>(s8, s9);
carry0<21>(s9, s10);
carry0<21>(s10, s11);
carry0<21>(s11, s12);
s[0] = static_cast<uint8_t>(s0 >> 0);
s[1] = static_cast<uint8_t>(s0 >> 8);
s[2] = static_cast<uint8_t>((s0 >> 16) | (s1 << 5));
s[3] = static_cast<uint8_t>(s1 >> 3);
s[4] = static_cast<uint8_t>(s1 >> 11);
s[5] = static_cast<uint8_t>((s1 >> 19) | (s2 << 2));
s[6] = static_cast<uint8_t>(s2 >> 6);
s[7] = static_cast<uint8_t>((s2 >> 14) | (s3 << 7));
s[8] = static_cast<uint8_t>(s3 >> 1);
s[9] = static_cast<uint8_t>(s3 >> 9);
s[10] = static_cast<uint8_t>((s3 >> 17) | (s4 << 4));
s[11] = static_cast<uint8_t>(s4 >> 4);
s[12] = static_cast<uint8_t>(s4 >> 12);
s[13] = static_cast<uint8_t>((s4 >> 20) | (s5 << 1));
s[14] = static_cast<uint8_t>(s5 >> 7);
s[15] = static_cast<uint8_t>((s5 >> 15) | (s6 << 6));
s[16] = static_cast<uint8_t>(s6 >> 2);
s[17] = static_cast<uint8_t>(s6 >> 10);
s[18] = static_cast<uint8_t>((s6 >> 18) | (s7 << 3));
s[19] = static_cast<uint8_t>(s7 >> 5);
s[20] = static_cast<uint8_t>(s7 >> 13);
s[21] = static_cast<uint8_t>(s8 >> 0);
s[22] = static_cast<uint8_t>(s8 >> 8);
s[23] = static_cast<uint8_t>((s8 >> 16) | (s9 << 5));
s[24] = static_cast<uint8_t>(s9 >> 3);
s[25] = static_cast<uint8_t>(s9 >> 11);
s[26] = static_cast<uint8_t>((s9 >> 19) | (s10 << 2));
s[27] = static_cast<uint8_t>(s10 >> 6);
s[28] = static_cast<uint8_t>((s10 >> 14) | (s11 << 7));
s[29] = static_cast<uint8_t>(s11 >> 1);
s[30] = static_cast<uint8_t>(s11 >> 9);
s[31] = static_cast<uint8_t>(s11 >> 17);
}
}
|
