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