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[POLY1305_BLOCK_SIZE])13 void poly1305_core_setkey(struct poly1305_core_key *key,
14 const u8 raw_key[POLY1305_BLOCK_SIZE])
15 {
16 u64 t0, t1;
17
18 /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
19 t0 = get_unaligned_le64(&raw_key[0]);
20 t1 = get_unaligned_le64(&raw_key[8]);
21
22 key->key.r64[0] = t0 & 0xffc0fffffffULL;
23 key->key.r64[1] = ((t0 >> 44) | (t1 << 20)) & 0xfffffc0ffffULL;
24 key->key.r64[2] = ((t1 >> 24)) & 0x00ffffffc0fULL;
25
26 /* s = 20*r */
27 key->precomputed_s.r64[0] = key->key.r64[1] * 20;
28 key->precomputed_s.r64[1] = key->key.r64[2] * 20;
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 u64 hibit64;
38 u64 r0, r1, r2;
39 u64 s1, s2;
40 u64 h0, h1, h2;
41 u64 c;
42 u128 d0, d1, d2, d;
43
44 if (!nblocks)
45 return;
46
47 hibit64 = ((u64)hibit) << 40;
48
49 r0 = key->key.r64[0];
50 r1 = key->key.r64[1];
51 r2 = key->key.r64[2];
52
53 h0 = state->h64[0];
54 h1 = state->h64[1];
55 h2 = state->h64[2];
56
57 s1 = key->precomputed_s.r64[0];
58 s2 = key->precomputed_s.r64[1];
59
60 do {
61 u64 t0, t1;
62
63 /* h += m[i] */
64 t0 = get_unaligned_le64(&input[0]);
65 t1 = get_unaligned_le64(&input[8]);
66
67 h0 += t0 & 0xfffffffffffULL;
68 h1 += ((t0 >> 44) | (t1 << 20)) & 0xfffffffffffULL;
69 h2 += (((t1 >> 24)) & 0x3ffffffffffULL) | hibit64;
70
71 /* h *= r */
72 d0 = (u128)h0 * r0;
73 d = (u128)h1 * s2;
74 d0 += d;
75 d = (u128)h2 * s1;
76 d0 += d;
77 d1 = (u128)h0 * r1;
78 d = (u128)h1 * r0;
79 d1 += d;
80 d = (u128)h2 * s2;
81 d1 += d;
82 d2 = (u128)h0 * r2;
83 d = (u128)h1 * r1;
84 d2 += d;
85 d = (u128)h2 * r0;
86 d2 += d;
87
88 /* (partial) h %= p */
89 c = (u64)(d0 >> 44);
90 h0 = (u64)d0 & 0xfffffffffffULL;
91 d1 += c;
92 c = (u64)(d1 >> 44);
93 h1 = (u64)d1 & 0xfffffffffffULL;
94 d2 += c;
95 c = (u64)(d2 >> 42);
96 h2 = (u64)d2 & 0x3ffffffffffULL;
97 h0 += c * 5;
98 c = h0 >> 44;
99 h0 = h0 & 0xfffffffffffULL;
100 h1 += c;
101
102 input += POLY1305_BLOCK_SIZE;
103 } while (--nblocks);
104
105 state->h64[0] = h0;
106 state->h64[1] = h1;
107 state->h64[2] = h2;
108 }
109 EXPORT_SYMBOL(poly1305_core_blocks);
110
poly1305_core_emit(const struct poly1305_state * state,const u32 nonce[4],void * dst)111 void poly1305_core_emit(const struct poly1305_state *state, const u32 nonce[4],
112 void *dst)
113 {
114 u8 *mac = dst;
115 u64 h0, h1, h2, c;
116 u64 g0, g1, g2;
117 u64 t0, t1;
118
119 /* fully carry h */
120 h0 = state->h64[0];
121 h1 = state->h64[1];
122 h2 = state->h64[2];
123
124 c = h1 >> 44;
125 h1 &= 0xfffffffffffULL;
126 h2 += c;
127 c = h2 >> 42;
128 h2 &= 0x3ffffffffffULL;
129 h0 += c * 5;
130 c = h0 >> 44;
131 h0 &= 0xfffffffffffULL;
132 h1 += c;
133 c = h1 >> 44;
134 h1 &= 0xfffffffffffULL;
135 h2 += c;
136 c = h2 >> 42;
137 h2 &= 0x3ffffffffffULL;
138 h0 += c * 5;
139 c = h0 >> 44;
140 h0 &= 0xfffffffffffULL;
141 h1 += c;
142
143 /* compute h + -p */
144 g0 = h0 + 5;
145 c = g0 >> 44;
146 g0 &= 0xfffffffffffULL;
147 g1 = h1 + c;
148 c = g1 >> 44;
149 g1 &= 0xfffffffffffULL;
150 g2 = h2 + c - (1ULL << 42);
151
152 /* select h if h < p, or h + -p if h >= p */
153 c = (g2 >> ((sizeof(u64) * 8) - 1)) - 1;
154 g0 &= c;
155 g1 &= c;
156 g2 &= c;
157 c = ~c;
158 h0 = (h0 & c) | g0;
159 h1 = (h1 & c) | g1;
160 h2 = (h2 & c) | g2;
161
162 if (likely(nonce)) {
163 /* h = (h + nonce) */
164 t0 = ((u64)nonce[1] << 32) | nonce[0];
165 t1 = ((u64)nonce[3] << 32) | nonce[2];
166
167 h0 += t0 & 0xfffffffffffULL;
168 c = h0 >> 44;
169 h0 &= 0xfffffffffffULL;
170 h1 += (((t0 >> 44) | (t1 << 20)) & 0xfffffffffffULL) + c;
171 c = h1 >> 44;
172 h1 &= 0xfffffffffffULL;
173 h2 += (((t1 >> 24)) & 0x3ffffffffffULL) + c;
174 h2 &= 0x3ffffffffffULL;
175 }
176
177 /* mac = h % (2^128) */
178 h0 = h0 | (h1 << 44);
179 h1 = (h1 >> 20) | (h2 << 24);
180
181 put_unaligned_le64(h0, &mac[0]);
182 put_unaligned_le64(h1, &mac[8]);
183 }
184 EXPORT_SYMBOL(poly1305_core_emit);
185