Line data Source code
1 : // Copyright (c) 2019 The Bitcoin Core developers
2 : // Distributed under the MIT software license, see the accompanying
3 : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
4 :
5 : #include <crypto/common.h>
6 : #include <crypto/poly1305.h>
7 :
8 : #include <string.h>
9 :
10 : namespace poly1305_donna {
11 :
12 : // Based on the public domain implementation by Andrew Moon
13 : // poly1305-donna-32.h from https://github.com/floodyberry/poly1305-donna
14 :
15 0 : void poly1305_init(poly1305_context *st, const unsigned char key[32]) noexcept {
16 : /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
17 0 : st->r[0] = (ReadLE32(&key[ 0]) ) & 0x3ffffff;
18 0 : st->r[1] = (ReadLE32(&key[ 3]) >> 2) & 0x3ffff03;
19 0 : st->r[2] = (ReadLE32(&key[ 6]) >> 4) & 0x3ffc0ff;
20 0 : st->r[3] = (ReadLE32(&key[ 9]) >> 6) & 0x3f03fff;
21 0 : st->r[4] = (ReadLE32(&key[12]) >> 8) & 0x00fffff;
22 :
23 : /* h = 0 */
24 0 : st->h[0] = 0;
25 0 : st->h[1] = 0;
26 0 : st->h[2] = 0;
27 0 : st->h[3] = 0;
28 0 : st->h[4] = 0;
29 :
30 : /* save pad for later */
31 0 : st->pad[0] = ReadLE32(&key[16]);
32 0 : st->pad[1] = ReadLE32(&key[20]);
33 0 : st->pad[2] = ReadLE32(&key[24]);
34 0 : st->pad[3] = ReadLE32(&key[28]);
35 :
36 0 : st->leftover = 0;
37 0 : st->final = 0;
38 0 : }
39 :
40 0 : static void poly1305_blocks(poly1305_context *st, const unsigned char *m, size_t bytes) noexcept {
41 0 : const uint32_t hibit = (st->final) ? 0 : (1UL << 24); /* 1 << 128 */
42 : uint32_t r0,r1,r2,r3,r4;
43 : uint32_t s1,s2,s3,s4;
44 : uint32_t h0,h1,h2,h3,h4;
45 : uint64_t d0,d1,d2,d3,d4;
46 : uint32_t c;
47 :
48 0 : r0 = st->r[0];
49 0 : r1 = st->r[1];
50 0 : r2 = st->r[2];
51 0 : r3 = st->r[3];
52 0 : r4 = st->r[4];
53 :
54 0 : s1 = r1 * 5;
55 0 : s2 = r2 * 5;
56 0 : s3 = r3 * 5;
57 0 : s4 = r4 * 5;
58 :
59 0 : h0 = st->h[0];
60 0 : h1 = st->h[1];
61 0 : h2 = st->h[2];
62 0 : h3 = st->h[3];
63 0 : h4 = st->h[4];
64 :
65 0 : while (bytes >= POLY1305_BLOCK_SIZE) {
66 : /* h += m[i] */
67 0 : h0 += (ReadLE32(m+ 0) ) & 0x3ffffff;
68 0 : h1 += (ReadLE32(m+ 3) >> 2) & 0x3ffffff;
69 0 : h2 += (ReadLE32(m+ 6) >> 4) & 0x3ffffff;
70 0 : h3 += (ReadLE32(m+ 9) >> 6) & 0x3ffffff;
71 0 : h4 += (ReadLE32(m+12) >> 8) | hibit;
72 :
73 : /* h *= r */
74 0 : d0 = ((uint64_t)h0 * r0) + ((uint64_t)h1 * s4) + ((uint64_t)h2 * s3) + ((uint64_t)h3 * s2) + ((uint64_t)h4 * s1);
75 0 : d1 = ((uint64_t)h0 * r1) + ((uint64_t)h1 * r0) + ((uint64_t)h2 * s4) + ((uint64_t)h3 * s3) + ((uint64_t)h4 * s2);
76 0 : d2 = ((uint64_t)h0 * r2) + ((uint64_t)h1 * r1) + ((uint64_t)h2 * r0) + ((uint64_t)h3 * s4) + ((uint64_t)h4 * s3);
77 0 : d3 = ((uint64_t)h0 * r3) + ((uint64_t)h1 * r2) + ((uint64_t)h2 * r1) + ((uint64_t)h3 * r0) + ((uint64_t)h4 * s4);
78 0 : d4 = ((uint64_t)h0 * r4) + ((uint64_t)h1 * r3) + ((uint64_t)h2 * r2) + ((uint64_t)h3 * r1) + ((uint64_t)h4 * r0);
79 :
80 : /* (partial) h %= p */
81 0 : c = (uint32_t)(d0 >> 26); h0 = (uint32_t)d0 & 0x3ffffff;
82 0 : d1 += c; c = (uint32_t)(d1 >> 26); h1 = (uint32_t)d1 & 0x3ffffff;
83 0 : d2 += c; c = (uint32_t)(d2 >> 26); h2 = (uint32_t)d2 & 0x3ffffff;
84 0 : d3 += c; c = (uint32_t)(d3 >> 26); h3 = (uint32_t)d3 & 0x3ffffff;
85 0 : d4 += c; c = (uint32_t)(d4 >> 26); h4 = (uint32_t)d4 & 0x3ffffff;
86 0 : h0 += c * 5; c = (h0 >> 26); h0 = h0 & 0x3ffffff;
87 0 : h1 += c;
88 :
89 0 : m += POLY1305_BLOCK_SIZE;
90 0 : bytes -= POLY1305_BLOCK_SIZE;
91 : }
92 :
93 0 : st->h[0] = h0;
94 0 : st->h[1] = h1;
95 0 : st->h[2] = h2;
96 0 : st->h[3] = h3;
97 0 : st->h[4] = h4;
98 0 : }
99 :
100 0 : void poly1305_finish(poly1305_context *st, unsigned char mac[16]) noexcept {
101 : uint32_t h0,h1,h2,h3,h4,c;
102 : uint32_t g0,g1,g2,g3,g4;
103 : uint64_t f;
104 : uint32_t mask;
105 :
106 : /* process the remaining block */
107 0 : if (st->leftover) {
108 0 : size_t i = st->leftover;
109 0 : st->buffer[i++] = 1;
110 0 : for (; i < POLY1305_BLOCK_SIZE; i++) {
111 0 : st->buffer[i] = 0;
112 0 : }
113 0 : st->final = 1;
114 0 : poly1305_blocks(st, st->buffer, POLY1305_BLOCK_SIZE);
115 0 : }
116 :
117 : /* fully carry h */
118 0 : h0 = st->h[0];
119 0 : h1 = st->h[1];
120 0 : h2 = st->h[2];
121 0 : h3 = st->h[3];
122 0 : h4 = st->h[4];
123 :
124 0 : c = h1 >> 26; h1 = h1 & 0x3ffffff;
125 0 : h2 += c; c = h2 >> 26; h2 = h2 & 0x3ffffff;
126 0 : h3 += c; c = h3 >> 26; h3 = h3 & 0x3ffffff;
127 0 : h4 += c; c = h4 >> 26; h4 = h4 & 0x3ffffff;
128 0 : h0 += c * 5; c = h0 >> 26; h0 = h0 & 0x3ffffff;
129 0 : h1 += c;
130 :
131 : /* compute h + -p */
132 0 : g0 = h0 + 5; c = g0 >> 26; g0 &= 0x3ffffff;
133 0 : g1 = h1 + c; c = g1 >> 26; g1 &= 0x3ffffff;
134 0 : g2 = h2 + c; c = g2 >> 26; g2 &= 0x3ffffff;
135 0 : g3 = h3 + c; c = g3 >> 26; g3 &= 0x3ffffff;
136 0 : g4 = h4 + c - (1UL << 26);
137 :
138 : /* select h if h < p, or h + -p if h >= p */
139 0 : mask = (g4 >> ((sizeof(uint32_t) * 8) - 1)) - 1;
140 0 : g0 &= mask;
141 0 : g1 &= mask;
142 0 : g2 &= mask;
143 0 : g3 &= mask;
144 0 : g4 &= mask;
145 0 : mask = ~mask;
146 0 : h0 = (h0 & mask) | g0;
147 0 : h1 = (h1 & mask) | g1;
148 0 : h2 = (h2 & mask) | g2;
149 0 : h3 = (h3 & mask) | g3;
150 0 : h4 = (h4 & mask) | g4;
151 :
152 : /* h = h % (2^128) */
153 0 : h0 = ((h0 ) | (h1 << 26)) & 0xffffffff;
154 0 : h1 = ((h1 >> 6) | (h2 << 20)) & 0xffffffff;
155 0 : h2 = ((h2 >> 12) | (h3 << 14)) & 0xffffffff;
156 0 : h3 = ((h3 >> 18) | (h4 << 8)) & 0xffffffff;
157 :
158 : /* mac = (h + pad) % (2^128) */
159 0 : f = (uint64_t)h0 + st->pad[0] ; h0 = (uint32_t)f;
160 0 : f = (uint64_t)h1 + st->pad[1] + (f >> 32); h1 = (uint32_t)f;
161 0 : f = (uint64_t)h2 + st->pad[2] + (f >> 32); h2 = (uint32_t)f;
162 0 : f = (uint64_t)h3 + st->pad[3] + (f >> 32); h3 = (uint32_t)f;
163 :
164 0 : WriteLE32(mac + 0, h0);
165 0 : WriteLE32(mac + 4, h1);
166 0 : WriteLE32(mac + 8, h2);
167 0 : WriteLE32(mac + 12, h3);
168 :
169 : /* zero out the state */
170 0 : st->h[0] = 0;
171 0 : st->h[1] = 0;
172 0 : st->h[2] = 0;
173 0 : st->h[3] = 0;
174 0 : st->h[4] = 0;
175 0 : st->r[0] = 0;
176 0 : st->r[1] = 0;
177 0 : st->r[2] = 0;
178 0 : st->r[3] = 0;
179 0 : st->r[4] = 0;
180 0 : st->pad[0] = 0;
181 0 : st->pad[1] = 0;
182 0 : st->pad[2] = 0;
183 0 : st->pad[3] = 0;
184 0 : }
185 :
186 0 : void poly1305_update(poly1305_context *st, const unsigned char *m, size_t bytes) noexcept {
187 : size_t i;
188 :
189 : /* handle leftover */
190 0 : if (st->leftover) {
191 0 : size_t want = (POLY1305_BLOCK_SIZE - st->leftover);
192 0 : if (want > bytes) {
193 0 : want = bytes;
194 0 : }
195 0 : for (i = 0; i < want; i++) {
196 0 : st->buffer[st->leftover + i] = m[i];
197 0 : }
198 0 : bytes -= want;
199 0 : m += want;
200 0 : st->leftover += want;
201 0 : if (st->leftover < POLY1305_BLOCK_SIZE) return;
202 0 : poly1305_blocks(st, st->buffer, POLY1305_BLOCK_SIZE);
203 0 : st->leftover = 0;
204 0 : }
205 :
206 : /* process full blocks */
207 0 : if (bytes >= POLY1305_BLOCK_SIZE) {
208 0 : size_t want = (bytes & ~(POLY1305_BLOCK_SIZE - 1));
209 0 : poly1305_blocks(st, m, want);
210 0 : m += want;
211 0 : bytes -= want;
212 0 : }
213 :
214 : /* store leftover */
215 0 : if (bytes) {
216 0 : for (i = 0; i < bytes; i++) {
217 0 : st->buffer[st->leftover + i] = m[i];
218 0 : }
219 0 : st->leftover += bytes;
220 0 : }
221 0 : }
222 :
223 : } // namespace poly1305_donna
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