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
|
/*
poly1305 implementation using 32 bit * 32 bit = 64 bit multiplication and 64 bit addition
*/
#define POLY1305_IMPLEMENTATION_NAME "donna32"
#if defined(_MSC_VER)
# define POLY1305_NOINLINE __declspec(noinline)
#elif defined(__GNUC__)
# define POLY1305_NOINLINE __attribute__((noinline))
#else
# define POLY1305_NOINLINE
#endif
#define poly1305_block_size 16
/* 17 + sizeof(unsigned long long) + 14*sizeof(unsigned long) */
typedef struct poly1305_state_internal_t {
unsigned long r[5];
unsigned long h[5];
unsigned long pad[4];
unsigned long long leftover;
unsigned char buffer[poly1305_block_size];
unsigned char final;
} poly1305_state_internal_t;
/* interpret four 8 bit unsigned integers as a 32 bit unsigned integer in little endian */
static unsigned long
U8TO32(const unsigned char *p) {
return
(((unsigned long)(p[0] & 0xff) ) |
((unsigned long)(p[1] & 0xff) << 8) |
((unsigned long)(p[2] & 0xff) << 16) |
((unsigned long)(p[3] & 0xff) << 24));
}
/* store a 32 bit unsigned integer as four 8 bit unsigned integers in little endian */
static void
U32TO8(unsigned char *p, unsigned long v) {
p[0] = (v ) & 0xff;
p[1] = (v >> 8) & 0xff;
p[2] = (v >> 16) & 0xff;
p[3] = (v >> 24) & 0xff;
}
static void
poly1305_init(poly1305_context *ctx, const unsigned char key[32]) {
poly1305_state_internal_t *st = (poly1305_state_internal_t *)(void *)ctx;
/* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
st->r[0] = (U8TO32(&key[ 0]) ) & 0x3ffffff;
st->r[1] = (U8TO32(&key[ 3]) >> 2) & 0x3ffff03;
st->r[2] = (U8TO32(&key[ 6]) >> 4) & 0x3ffc0ff;
st->r[3] = (U8TO32(&key[ 9]) >> 6) & 0x3f03fff;
st->r[4] = (U8TO32(&key[12]) >> 8) & 0x00fffff;
/* h = 0 */
st->h[0] = 0;
st->h[1] = 0;
st->h[2] = 0;
st->h[3] = 0;
st->h[4] = 0;
/* save pad for later */
st->pad[0] = U8TO32(&key[16]);
st->pad[1] = U8TO32(&key[20]);
st->pad[2] = U8TO32(&key[24]);
st->pad[3] = U8TO32(&key[28]);
st->leftover = 0;
st->final = 0;
}
static void
poly1305_blocks(poly1305_state_internal_t *st, const unsigned char *m, unsigned long long bytes) {
const unsigned long hibit = (st->final) ? 0 : (1 << 24); /* 1 << 128 */
unsigned long r0,r1,r2,r3,r4;
unsigned long s1,s2,s3,s4;
unsigned long h0,h1,h2,h3,h4;
unsigned long long d0,d1,d2,d3,d4;
unsigned long c;
r0 = st->r[0];
r1 = st->r[1];
r2 = st->r[2];
r3 = st->r[3];
r4 = st->r[4];
s1 = r1 * 5;
s2 = r2 * 5;
s3 = r3 * 5;
s4 = r4 * 5;
h0 = st->h[0];
h1 = st->h[1];
h2 = st->h[2];
h3 = st->h[3];
h4 = st->h[4];
while (bytes >= poly1305_block_size) {
/* h += m[i] */
h0 += (U8TO32(m+ 0) ) & 0x3ffffff;
h1 += (U8TO32(m+ 3) >> 2) & 0x3ffffff;
h2 += (U8TO32(m+ 6) >> 4) & 0x3ffffff;
h3 += (U8TO32(m+ 9) >> 6) & 0x3ffffff;
h4 += (U8TO32(m+12) >> 8) | hibit;
/* h *= r */
d0 = ((unsigned long long)h0 * r0) + ((unsigned long long)h1 * s4) + ((unsigned long long)h2 * s3) + ((unsigned long long)h3 * s2) + ((unsigned long long)h4 * s1);
d1 = ((unsigned long long)h0 * r1) + ((unsigned long long)h1 * r0) + ((unsigned long long)h2 * s4) + ((unsigned long long)h3 * s3) + ((unsigned long long)h4 * s2);
d2 = ((unsigned long long)h0 * r2) + ((unsigned long long)h1 * r1) + ((unsigned long long)h2 * r0) + ((unsigned long long)h3 * s4) + ((unsigned long long)h4 * s3);
d3 = ((unsigned long long)h0 * r3) + ((unsigned long long)h1 * r2) + ((unsigned long long)h2 * r1) + ((unsigned long long)h3 * r0) + ((unsigned long long)h4 * s4);
d4 = ((unsigned long long)h0 * r4) + ((unsigned long long)h1 * r3) + ((unsigned long long)h2 * r2) + ((unsigned long long)h3 * r1) + ((unsigned long long)h4 * r0);
/* (partial) h %= p */
c = (unsigned long)(d0 >> 26); h0 = (unsigned long)d0 & 0x3ffffff;
d1 += c; c = (unsigned long)(d1 >> 26); h1 = (unsigned long)d1 & 0x3ffffff;
d2 += c; c = (unsigned long)(d2 >> 26); h2 = (unsigned long)d2 & 0x3ffffff;
d3 += c; c = (unsigned long)(d3 >> 26); h3 = (unsigned long)d3 & 0x3ffffff;
d4 += c; c = (unsigned long)(d4 >> 26); h4 = (unsigned long)d4 & 0x3ffffff;
h0 += c * 5; c = (h0 >> 26); h0 = h0 & 0x3ffffff;
h1 += c;
m += poly1305_block_size;
bytes -= poly1305_block_size;
}
st->h[0] = h0;
st->h[1] = h1;
st->h[2] = h2;
st->h[3] = h3;
st->h[4] = h4;
}
static POLY1305_NOINLINE void
poly1305_finish(poly1305_context *ctx, unsigned char mac[16]) {
poly1305_state_internal_t *st = (poly1305_state_internal_t *)(void *)ctx;
unsigned long h0,h1,h2,h3,h4,c;
unsigned long g0,g1,g2,g3,g4;
unsigned long long f;
unsigned long mask;
/* process the remaining block */
if (st->leftover) {
unsigned long long i = st->leftover;
st->buffer[i++] = 1;
for (; i < poly1305_block_size; i++)
st->buffer[i] = 0;
st->final = 1;
poly1305_blocks(st, st->buffer, poly1305_block_size);
}
/* fully carry h */
h0 = st->h[0];
h1 = st->h[1];
h2 = st->h[2];
h3 = st->h[3];
h4 = st->h[4];
c = h1 >> 26; h1 = h1 & 0x3ffffff;
h2 += c; c = h2 >> 26; h2 = h2 & 0x3ffffff;
h3 += c; c = h3 >> 26; h3 = h3 & 0x3ffffff;
h4 += c; c = h4 >> 26; h4 = h4 & 0x3ffffff;
h0 += c * 5; c = h0 >> 26; h0 = h0 & 0x3ffffff;
h1 += c;
/* compute h + -p */
g0 = h0 + 5; c = g0 >> 26; g0 &= 0x3ffffff;
g1 = h1 + c; c = g1 >> 26; g1 &= 0x3ffffff;
g2 = h2 + c; c = g2 >> 26; g2 &= 0x3ffffff;
g3 = h3 + c; c = g3 >> 26; g3 &= 0x3ffffff;
g4 = h4 + c - (1 << 26);
/* select h if h < p, or h + -p if h >= p */
mask = (g4 >> ((sizeof(unsigned long) * 8) - 1)) - 1;
g0 &= mask;
g1 &= mask;
g2 &= mask;
g3 &= mask;
g4 &= mask;
mask = ~mask;
h0 = (h0 & mask) | g0;
h1 = (h1 & mask) | g1;
h2 = (h2 & mask) | g2;
h3 = (h3 & mask) | g3;
h4 = (h4 & mask) | g4;
/* h = h % (2^128) */
h0 = ((h0 ) | (h1 << 26)) & 0xffffffff;
h1 = ((h1 >> 6) | (h2 << 20)) & 0xffffffff;
h2 = ((h2 >> 12) | (h3 << 14)) & 0xffffffff;
h3 = ((h3 >> 18) | (h4 << 8)) & 0xffffffff;
/* mac = (h + pad) % (2^128) */
f = (unsigned long long)h0 + st->pad[0] ; h0 = (unsigned long)f;
f = (unsigned long long)h1 + st->pad[1] + (f >> 32); h1 = (unsigned long)f;
f = (unsigned long long)h2 + st->pad[2] + (f >> 32); h2 = (unsigned long)f;
f = (unsigned long long)h3 + st->pad[3] + (f >> 32); h3 = (unsigned long)f;
U32TO8(mac + 0, h0);
U32TO8(mac + 4, h1);
U32TO8(mac + 8, h2);
U32TO8(mac + 12, h3);
/* zero out the state */
sodium_memzero((void *)st, sizeof *st);
}
|
