1 // SPDX-License-Identifier: GPL-2.0 OR MIT
2 /*
3 * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
4 *
5 * This is based in part on Andrew Moon's poly1305-donna, which is in the
6 * public domain.
7 */
8
9 #include <crypto/internal/poly1305.h>
10 #include <linux/export.h>
11 #include <linux/kernel.h>
12 #include <linux/unaligned.h>
13
poly1305_core_setkey(struct poly1305_core_key * key,const u8 raw_key[POLY1305_BLOCK_SIZE])14 void poly1305_core_setkey(struct poly1305_core_key *key,
15 const u8 raw_key[POLY1305_BLOCK_SIZE])
16 {
17 /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
18 key->key.r[0] = (get_unaligned_le32(&raw_key[0])) & 0x3ffffff;
19 key->key.r[1] = (get_unaligned_le32(&raw_key[3]) >> 2) & 0x3ffff03;
20 key->key.r[2] = (get_unaligned_le32(&raw_key[6]) >> 4) & 0x3ffc0ff;
21 key->key.r[3] = (get_unaligned_le32(&raw_key[9]) >> 6) & 0x3f03fff;
22 key->key.r[4] = (get_unaligned_le32(&raw_key[12]) >> 8) & 0x00fffff;
23
24 /* s = 5*r */
25 key->precomputed_s.r[0] = key->key.r[1] * 5;
26 key->precomputed_s.r[1] = key->key.r[2] * 5;
27 key->precomputed_s.r[2] = key->key.r[3] * 5;
28 key->precomputed_s.r[3] = key->key.r[4] * 5;
29 }
30 EXPORT_SYMBOL(poly1305_core_setkey);
31
poly1305_core_blocks(struct poly1305_state * state,const struct poly1305_core_key * key,const void * src,unsigned int nblocks,u32 hibit)32 void poly1305_core_blocks(struct poly1305_state *state,
33 const struct poly1305_core_key *key, const void *src,
34 unsigned int nblocks, u32 hibit)
35 {
36 const u8 *input = src;
37 u32 r0, r1, r2, r3, r4;
38 u32 s1, s2, s3, s4;
39 u32 h0, h1, h2, h3, h4;
40 u64 d0, d1, d2, d3, d4;
41 u32 c;
42
43 if (!nblocks)
44 return;
45
46 hibit <<= 24;
47
48 r0 = key->key.r[0];
49 r1 = key->key.r[1];
50 r2 = key->key.r[2];
51 r3 = key->key.r[3];
52 r4 = key->key.r[4];
53
54 s1 = key->precomputed_s.r[0];
55 s2 = key->precomputed_s.r[1];
56 s3 = key->precomputed_s.r[2];
57 s4 = key->precomputed_s.r[3];
58
59 h0 = state->h[0];
60 h1 = state->h[1];
61 h2 = state->h[2];
62 h3 = state->h[3];
63 h4 = state->h[4];
64
65 do {
66 /* h += m[i] */
67 h0 += (get_unaligned_le32(&input[0])) & 0x3ffffff;
68 h1 += (get_unaligned_le32(&input[3]) >> 2) & 0x3ffffff;
69 h2 += (get_unaligned_le32(&input[6]) >> 4) & 0x3ffffff;
70 h3 += (get_unaligned_le32(&input[9]) >> 6) & 0x3ffffff;
71 h4 += (get_unaligned_le32(&input[12]) >> 8) | hibit;
72
73 /* h *= r */
74 d0 = ((u64)h0 * r0) + ((u64)h1 * s4) +
75 ((u64)h2 * s3) + ((u64)h3 * s2) +
76 ((u64)h4 * s1);
77 d1 = ((u64)h0 * r1) + ((u64)h1 * r0) +
78 ((u64)h2 * s4) + ((u64)h3 * s3) +
79 ((u64)h4 * s2);
80 d2 = ((u64)h0 * r2) + ((u64)h1 * r1) +
81 ((u64)h2 * r0) + ((u64)h3 * s4) +
82 ((u64)h4 * s3);
83 d3 = ((u64)h0 * r3) + ((u64)h1 * r2) +
84 ((u64)h2 * r1) + ((u64)h3 * r0) +
85 ((u64)h4 * s4);
86 d4 = ((u64)h0 * r4) + ((u64)h1 * r3) +
87 ((u64)h2 * r2) + ((u64)h3 * r1) +
88 ((u64)h4 * r0);
89
90 /* (partial) h %= p */
91 c = (u32)(d0 >> 26);
92 h0 = (u32)d0 & 0x3ffffff;
93 d1 += c;
94 c = (u32)(d1 >> 26);
95 h1 = (u32)d1 & 0x3ffffff;
96 d2 += c;
97 c = (u32)(d2 >> 26);
98 h2 = (u32)d2 & 0x3ffffff;
99 d3 += c;
100 c = (u32)(d3 >> 26);
101 h3 = (u32)d3 & 0x3ffffff;
102 d4 += c;
103 c = (u32)(d4 >> 26);
104 h4 = (u32)d4 & 0x3ffffff;
105 h0 += c * 5;
106 c = (h0 >> 26);
107 h0 = h0 & 0x3ffffff;
108 h1 += c;
109
110 input += POLY1305_BLOCK_SIZE;
111 } while (--nblocks);
112
113 state->h[0] = h0;
114 state->h[1] = h1;
115 state->h[2] = h2;
116 state->h[3] = h3;
117 state->h[4] = h4;
118 }
119 EXPORT_SYMBOL(poly1305_core_blocks);
120
poly1305_core_emit(const struct poly1305_state * state,const u32 nonce[4],void * dst)121 void poly1305_core_emit(const struct poly1305_state *state, const u32 nonce[4],
122 void *dst)
123 {
124 u8 *mac = dst;
125 u32 h0, h1, h2, h3, h4, c;
126 u32 g0, g1, g2, g3, g4;
127 u64 f;
128 u32 mask;
129
130 /* fully carry h */
131 h0 = state->h[0];
132 h1 = state->h[1];
133 h2 = state->h[2];
134 h3 = state->h[3];
135 h4 = state->h[4];
136
137 c = h1 >> 26;
138 h1 = h1 & 0x3ffffff;
139 h2 += c;
140 c = h2 >> 26;
141 h2 = h2 & 0x3ffffff;
142 h3 += c;
143 c = h3 >> 26;
144 h3 = h3 & 0x3ffffff;
145 h4 += c;
146 c = h4 >> 26;
147 h4 = h4 & 0x3ffffff;
148 h0 += c * 5;
149 c = h0 >> 26;
150 h0 = h0 & 0x3ffffff;
151 h1 += c;
152
153 /* compute h + -p */
154 g0 = h0 + 5;
155 c = g0 >> 26;
156 g0 &= 0x3ffffff;
157 g1 = h1 + c;
158 c = g1 >> 26;
159 g1 &= 0x3ffffff;
160 g2 = h2 + c;
161 c = g2 >> 26;
162 g2 &= 0x3ffffff;
163 g3 = h3 + c;
164 c = g3 >> 26;
165 g3 &= 0x3ffffff;
166 g4 = h4 + c - (1UL << 26);
167
168 /* select h if h < p, or h + -p if h >= p */
169 mask = (g4 >> ((sizeof(u32) * 8) - 1)) - 1;
170 g0 &= mask;
171 g1 &= mask;
172 g2 &= mask;
173 g3 &= mask;
174 g4 &= mask;
175 mask = ~mask;
176
177 h0 = (h0 & mask) | g0;
178 h1 = (h1 & mask) | g1;
179 h2 = (h2 & mask) | g2;
180 h3 = (h3 & mask) | g3;
181 h4 = (h4 & mask) | g4;
182
183 /* h = h % (2^128) */
184 h0 = ((h0) | (h1 << 26)) & 0xffffffff;
185 h1 = ((h1 >> 6) | (h2 << 20)) & 0xffffffff;
186 h2 = ((h2 >> 12) | (h3 << 14)) & 0xffffffff;
187 h3 = ((h3 >> 18) | (h4 << 8)) & 0xffffffff;
188
189 if (likely(nonce)) {
190 /* mac = (h + nonce) % (2^128) */
191 f = (u64)h0 + nonce[0];
192 h0 = (u32)f;
193 f = (u64)h1 + nonce[1] + (f >> 32);
194 h1 = (u32)f;
195 f = (u64)h2 + nonce[2] + (f >> 32);
196 h2 = (u32)f;
197 f = (u64)h3 + nonce[3] + (f >> 32);
198 h3 = (u32)f;
199 }
200
201 put_unaligned_le32(h0, &mac[0]);
202 put_unaligned_le32(h1, &mac[4]);
203 put_unaligned_le32(h2, &mac[8]);
204 put_unaligned_le32(h3, &mac[12]);
205 }
206 EXPORT_SYMBOL(poly1305_core_emit);
207