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
|
/*
* Copyright 2017-2018 The OpenSSL Project Authors. All Rights Reserved.
* Copyright 2014 Cryptography Research, Inc.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*
* Originally written by Mike Hamburg
*/
#ifndef HEADER_FIELD_H
# define HEADER_FIELD_H
# include "internal/constant_time_locl.h"
# include <string.h>
# include <assert.h>
# include "word.h"
# define NLIMBS (64/sizeof(word_t))
# define X_SER_BYTES 56
# define SER_BYTES 56
# if defined(__GNUC__) || defined(__clang__)
# define INLINE_UNUSED __inline__ __attribute__((__unused__,__always_inline__))
# define RESTRICT __restrict__
# define ALIGNED __attribute__((__aligned__(16)))
# else
# define INLINE_UNUSED ossl_inline
# define RESTRICT
# define ALIGNED
# endif
typedef struct gf_s {
word_t limb[NLIMBS];
} ALIGNED gf_s, gf[1];
/* RFC 7748 support */
# define X_PUBLIC_BYTES X_SER_BYTES
# define X_PRIVATE_BYTES X_PUBLIC_BYTES
# define X_PRIVATE_BITS 448
static INLINE_UNUSED void gf_copy(gf out, const gf a)
{
*out = *a;
}
static INLINE_UNUSED void gf_add_RAW(gf out, const gf a, const gf b);
static INLINE_UNUSED void gf_sub_RAW(gf out, const gf a, const gf b);
static INLINE_UNUSED void gf_bias(gf inout, int amount);
static INLINE_UNUSED void gf_weak_reduce(gf inout);
void gf_strong_reduce(gf inout);
void gf_add(gf out, const gf a, const gf b);
void gf_sub(gf out, const gf a, const gf b);
void gf_mul(gf_s * RESTRICT out, const gf a, const gf b);
void gf_mulw_unsigned(gf_s * RESTRICT out, const gf a, uint32_t b);
void gf_sqr(gf_s * RESTRICT out, const gf a);
mask_t gf_isr(gf a, const gf x); /** a^2 x = 1, QNR, or 0 if x=0. Return true if successful */
mask_t gf_eq(const gf x, const gf y);
mask_t gf_lobit(const gf x);
mask_t gf_hibit(const gf x);
void gf_serialize(uint8_t *serial, const gf x, int with_highbit);
mask_t gf_deserialize(gf x, const uint8_t serial[SER_BYTES], int with_hibit,
uint8_t hi_nmask);
# include "f_impl.h" /* Bring in the inline implementations */
# define LIMBPERM(i) (i)
# define LIMB_MASK(i) (((1)<<LIMB_PLACE_VALUE(i))-1)
static const gf ZERO = {{{0}}}, ONE = {{{1}}};
/* Square x, n times. */
static ossl_inline void gf_sqrn(gf_s * RESTRICT y, const gf x, int n)
{
gf tmp;
assert(n > 0);
if (n & 1) {
gf_sqr(y, x);
n--;
} else {
gf_sqr(tmp, x);
gf_sqr(y, tmp);
n -= 2;
}
for (; n; n -= 2) {
gf_sqr(tmp, y);
gf_sqr(y, tmp);
}
}
# define gf_add_nr gf_add_RAW
/* Subtract mod p. Bias by 2 and don't reduce */
static ossl_inline void gf_sub_nr(gf c, const gf a, const gf b)
{
gf_sub_RAW(c, a, b);
gf_bias(c, 2);
if (GF_HEADROOM < 3)
gf_weak_reduce(c);
}
/* Subtract mod p. Bias by amt but don't reduce. */
static ossl_inline void gf_subx_nr(gf c, const gf a, const gf b, int amt)
{
gf_sub_RAW(c, a, b);
gf_bias(c, amt);
if (GF_HEADROOM < amt + 1)
gf_weak_reduce(c);
}
/* Mul by signed int. Not constant-time WRT the sign of that int. */
static ossl_inline void gf_mulw(gf c, const gf a, int32_t w)
{
if (w > 0) {
gf_mulw_unsigned(c, a, w);
} else {
gf_mulw_unsigned(c, a, -w);
gf_sub(c, ZERO, c);
}
}
/* Constant time, x = is_z ? z : y */
static ossl_inline void gf_cond_sel(gf x, const gf y, const gf z, mask_t is_z)
{
size_t i;
for (i = 0; i < NLIMBS; i++) {
#if ARCH_WORD_BITS == 32
x[0].limb[i] = constant_time_select_32(is_z, z[0].limb[i],
y[0].limb[i]);
#else
/* Must be 64 bit */
x[0].limb[i] = constant_time_select_64(is_z, z[0].limb[i],
y[0].limb[i]);
#endif
}
}
/* Constant time, if (neg) x=-x; */
static ossl_inline void gf_cond_neg(gf x, mask_t neg)
{
gf y;
gf_sub(y, ZERO, x);
gf_cond_sel(x, x, y, neg);
}
/* Constant time, if (swap) (x,y) = (y,x); */
static ossl_inline void gf_cond_swap(gf x, gf_s * RESTRICT y, mask_t swap)
{
size_t i;
for (i = 0; i < NLIMBS; i++) {
#if ARCH_WORD_BITS == 32
constant_time_cond_swap_32(swap, &(x[0].limb[i]), &(y->limb[i]));
#else
/* Must be 64 bit */
constant_time_cond_swap_64(swap, &(x[0].limb[i]), &(y->limb[i]));
#endif
}
}
#endif /* HEADER_FIELD_H */
|
