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f979e014 MW |
1 | /* |
2 | * Poly1305 authenticator algorithm, RFC7539 | |
3 | * | |
4 | * Copyright (C) 2015 Martin Willi | |
5 | * | |
6 | * Based on public domain code by Andrew Moon and Daniel J. Bernstein. | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License as published by | |
10 | * the Free Software Foundation; either version 2 of the License, or | |
11 | * (at your option) any later version. | |
12 | */ | |
13 | ||
14 | #include <crypto/algapi.h> | |
15 | #include <crypto/internal/hash.h> | |
2546f811 | 16 | #include <crypto/poly1305.h> |
f979e014 MW |
17 | #include <linux/crypto.h> |
18 | #include <linux/kernel.h> | |
19 | #include <linux/module.h> | |
109e23bd | 20 | #include <asm/unaligned.h> |
f979e014 | 21 | |
f979e014 MW |
22 | static inline u64 mlt(u64 a, u64 b) |
23 | { | |
24 | return a * b; | |
25 | } | |
26 | ||
27 | static inline u32 sr(u64 v, u_char n) | |
28 | { | |
29 | return v >> n; | |
30 | } | |
31 | ||
32 | static inline u32 and(u32 v, u32 mask) | |
33 | { | |
34 | return v & mask; | |
35 | } | |
36 | ||
2546f811 | 37 | int crypto_poly1305_init(struct shash_desc *desc) |
f979e014 MW |
38 | { |
39 | struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc); | |
40 | ||
41 | memset(dctx->h, 0, sizeof(dctx->h)); | |
42 | dctx->buflen = 0; | |
c2b7b20a MW |
43 | dctx->rset = false; |
44 | dctx->sset = false; | |
f979e014 MW |
45 | |
46 | return 0; | |
47 | } | |
2546f811 | 48 | EXPORT_SYMBOL_GPL(crypto_poly1305_init); |
f979e014 | 49 | |
c2b7b20a MW |
50 | static void poly1305_setrkey(struct poly1305_desc_ctx *dctx, const u8 *key) |
51 | { | |
f979e014 | 52 | /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */ |
109e23bd JD |
53 | dctx->r[0] = (get_unaligned_le32(key + 0) >> 0) & 0x3ffffff; |
54 | dctx->r[1] = (get_unaligned_le32(key + 3) >> 2) & 0x3ffff03; | |
55 | dctx->r[2] = (get_unaligned_le32(key + 6) >> 4) & 0x3ffc0ff; | |
56 | dctx->r[3] = (get_unaligned_le32(key + 9) >> 6) & 0x3f03fff; | |
57 | dctx->r[4] = (get_unaligned_le32(key + 12) >> 8) & 0x00fffff; | |
c2b7b20a | 58 | } |
f979e014 | 59 | |
c2b7b20a MW |
60 | static void poly1305_setskey(struct poly1305_desc_ctx *dctx, const u8 *key) |
61 | { | |
109e23bd JD |
62 | dctx->s[0] = get_unaligned_le32(key + 0); |
63 | dctx->s[1] = get_unaligned_le32(key + 4); | |
64 | dctx->s[2] = get_unaligned_le32(key + 8); | |
65 | dctx->s[3] = get_unaligned_le32(key + 12); | |
f979e014 MW |
66 | } |
67 | ||
a16e772e EB |
68 | /* |
69 | * Poly1305 requires a unique key for each tag, which implies that we can't set | |
70 | * it on the tfm that gets accessed by multiple users simultaneously. Instead we | |
71 | * expect the key as the first 32 bytes in the update() call. | |
72 | */ | |
2546f811 MW |
73 | unsigned int crypto_poly1305_setdesckey(struct poly1305_desc_ctx *dctx, |
74 | const u8 *src, unsigned int srclen) | |
f979e014 | 75 | { |
2546f811 | 76 | if (!dctx->sset) { |
c2b7b20a MW |
77 | if (!dctx->rset && srclen >= POLY1305_BLOCK_SIZE) { |
78 | poly1305_setrkey(dctx, src); | |
79 | src += POLY1305_BLOCK_SIZE; | |
80 | srclen -= POLY1305_BLOCK_SIZE; | |
81 | dctx->rset = true; | |
82 | } | |
83 | if (srclen >= POLY1305_BLOCK_SIZE) { | |
84 | poly1305_setskey(dctx, src); | |
85 | src += POLY1305_BLOCK_SIZE; | |
86 | srclen -= POLY1305_BLOCK_SIZE; | |
87 | dctx->sset = true; | |
88 | } | |
89 | } | |
2546f811 MW |
90 | return srclen; |
91 | } | |
92 | EXPORT_SYMBOL_GPL(crypto_poly1305_setdesckey); | |
93 | ||
94 | static unsigned int poly1305_blocks(struct poly1305_desc_ctx *dctx, | |
95 | const u8 *src, unsigned int srclen, | |
96 | u32 hibit) | |
97 | { | |
98 | u32 r0, r1, r2, r3, r4; | |
99 | u32 s1, s2, s3, s4; | |
100 | u32 h0, h1, h2, h3, h4; | |
101 | u64 d0, d1, d2, d3, d4; | |
102 | unsigned int datalen; | |
103 | ||
104 | if (unlikely(!dctx->sset)) { | |
105 | datalen = crypto_poly1305_setdesckey(dctx, src, srclen); | |
106 | src += srclen - datalen; | |
107 | srclen = datalen; | |
108 | } | |
c2b7b20a MW |
109 | |
110 | r0 = dctx->r[0]; | |
111 | r1 = dctx->r[1]; | |
112 | r2 = dctx->r[2]; | |
113 | r3 = dctx->r[3]; | |
114 | r4 = dctx->r[4]; | |
f979e014 MW |
115 | |
116 | s1 = r1 * 5; | |
117 | s2 = r2 * 5; | |
118 | s3 = r3 * 5; | |
119 | s4 = r4 * 5; | |
120 | ||
121 | h0 = dctx->h[0]; | |
122 | h1 = dctx->h[1]; | |
123 | h2 = dctx->h[2]; | |
124 | h3 = dctx->h[3]; | |
125 | h4 = dctx->h[4]; | |
126 | ||
127 | while (likely(srclen >= POLY1305_BLOCK_SIZE)) { | |
128 | ||
129 | /* h += m[i] */ | |
109e23bd JD |
130 | h0 += (get_unaligned_le32(src + 0) >> 0) & 0x3ffffff; |
131 | h1 += (get_unaligned_le32(src + 3) >> 2) & 0x3ffffff; | |
132 | h2 += (get_unaligned_le32(src + 6) >> 4) & 0x3ffffff; | |
133 | h3 += (get_unaligned_le32(src + 9) >> 6) & 0x3ffffff; | |
134 | h4 += (get_unaligned_le32(src + 12) >> 8) | hibit; | |
f979e014 MW |
135 | |
136 | /* h *= r */ | |
137 | d0 = mlt(h0, r0) + mlt(h1, s4) + mlt(h2, s3) + | |
138 | mlt(h3, s2) + mlt(h4, s1); | |
139 | d1 = mlt(h0, r1) + mlt(h1, r0) + mlt(h2, s4) + | |
140 | mlt(h3, s3) + mlt(h4, s2); | |
141 | d2 = mlt(h0, r2) + mlt(h1, r1) + mlt(h2, r0) + | |
142 | mlt(h3, s4) + mlt(h4, s3); | |
143 | d3 = mlt(h0, r3) + mlt(h1, r2) + mlt(h2, r1) + | |
144 | mlt(h3, r0) + mlt(h4, s4); | |
145 | d4 = mlt(h0, r4) + mlt(h1, r3) + mlt(h2, r2) + | |
146 | mlt(h3, r1) + mlt(h4, r0); | |
147 | ||
148 | /* (partial) h %= p */ | |
149 | d1 += sr(d0, 26); h0 = and(d0, 0x3ffffff); | |
150 | d2 += sr(d1, 26); h1 = and(d1, 0x3ffffff); | |
151 | d3 += sr(d2, 26); h2 = and(d2, 0x3ffffff); | |
152 | d4 += sr(d3, 26); h3 = and(d3, 0x3ffffff); | |
153 | h0 += sr(d4, 26) * 5; h4 = and(d4, 0x3ffffff); | |
154 | h1 += h0 >> 26; h0 = h0 & 0x3ffffff; | |
155 | ||
156 | src += POLY1305_BLOCK_SIZE; | |
157 | srclen -= POLY1305_BLOCK_SIZE; | |
158 | } | |
159 | ||
160 | dctx->h[0] = h0; | |
161 | dctx->h[1] = h1; | |
162 | dctx->h[2] = h2; | |
163 | dctx->h[3] = h3; | |
164 | dctx->h[4] = h4; | |
165 | ||
166 | return srclen; | |
167 | } | |
168 | ||
2546f811 | 169 | int crypto_poly1305_update(struct shash_desc *desc, |
f979e014 MW |
170 | const u8 *src, unsigned int srclen) |
171 | { | |
172 | struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc); | |
f979e014 MW |
173 | unsigned int bytes; |
174 | ||
175 | if (unlikely(dctx->buflen)) { | |
176 | bytes = min(srclen, POLY1305_BLOCK_SIZE - dctx->buflen); | |
177 | memcpy(dctx->buf + dctx->buflen, src, bytes); | |
178 | src += bytes; | |
179 | srclen -= bytes; | |
180 | dctx->buflen += bytes; | |
181 | ||
182 | if (dctx->buflen == POLY1305_BLOCK_SIZE) { | |
c2b7b20a | 183 | poly1305_blocks(dctx, dctx->buf, |
f979e014 MW |
184 | POLY1305_BLOCK_SIZE, 1 << 24); |
185 | dctx->buflen = 0; | |
186 | } | |
187 | } | |
188 | ||
189 | if (likely(srclen >= POLY1305_BLOCK_SIZE)) { | |
c2b7b20a | 190 | bytes = poly1305_blocks(dctx, src, srclen, 1 << 24); |
f979e014 MW |
191 | src += srclen - bytes; |
192 | srclen = bytes; | |
193 | } | |
194 | ||
195 | if (unlikely(srclen)) { | |
196 | dctx->buflen = srclen; | |
197 | memcpy(dctx->buf, src, srclen); | |
198 | } | |
199 | ||
200 | return 0; | |
201 | } | |
2546f811 | 202 | EXPORT_SYMBOL_GPL(crypto_poly1305_update); |
f979e014 | 203 | |
2546f811 | 204 | int crypto_poly1305_final(struct shash_desc *desc, u8 *dst) |
f979e014 MW |
205 | { |
206 | struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc); | |
f979e014 MW |
207 | u32 h0, h1, h2, h3, h4; |
208 | u32 g0, g1, g2, g3, g4; | |
209 | u32 mask; | |
210 | u64 f = 0; | |
211 | ||
c2b7b20a MW |
212 | if (unlikely(!dctx->sset)) |
213 | return -ENOKEY; | |
214 | ||
f979e014 MW |
215 | if (unlikely(dctx->buflen)) { |
216 | dctx->buf[dctx->buflen++] = 1; | |
217 | memset(dctx->buf + dctx->buflen, 0, | |
218 | POLY1305_BLOCK_SIZE - dctx->buflen); | |
c2b7b20a | 219 | poly1305_blocks(dctx, dctx->buf, POLY1305_BLOCK_SIZE, 0); |
f979e014 MW |
220 | } |
221 | ||
222 | /* fully carry h */ | |
223 | h0 = dctx->h[0]; | |
224 | h1 = dctx->h[1]; | |
225 | h2 = dctx->h[2]; | |
226 | h3 = dctx->h[3]; | |
227 | h4 = dctx->h[4]; | |
228 | ||
229 | h2 += (h1 >> 26); h1 = h1 & 0x3ffffff; | |
230 | h3 += (h2 >> 26); h2 = h2 & 0x3ffffff; | |
231 | h4 += (h3 >> 26); h3 = h3 & 0x3ffffff; | |
232 | h0 += (h4 >> 26) * 5; h4 = h4 & 0x3ffffff; | |
233 | h1 += (h0 >> 26); h0 = h0 & 0x3ffffff; | |
234 | ||
235 | /* compute h + -p */ | |
236 | g0 = h0 + 5; | |
237 | g1 = h1 + (g0 >> 26); g0 &= 0x3ffffff; | |
238 | g2 = h2 + (g1 >> 26); g1 &= 0x3ffffff; | |
239 | g3 = h3 + (g2 >> 26); g2 &= 0x3ffffff; | |
240 | g4 = h4 + (g3 >> 26) - (1 << 26); g3 &= 0x3ffffff; | |
241 | ||
242 | /* select h if h < p, or h + -p if h >= p */ | |
243 | mask = (g4 >> ((sizeof(u32) * 8) - 1)) - 1; | |
244 | g0 &= mask; | |
245 | g1 &= mask; | |
246 | g2 &= mask; | |
247 | g3 &= mask; | |
248 | g4 &= mask; | |
249 | mask = ~mask; | |
250 | h0 = (h0 & mask) | g0; | |
251 | h1 = (h1 & mask) | g1; | |
252 | h2 = (h2 & mask) | g2; | |
253 | h3 = (h3 & mask) | g3; | |
254 | h4 = (h4 & mask) | g4; | |
255 | ||
256 | /* h = h % (2^128) */ | |
257 | h0 = (h0 >> 0) | (h1 << 26); | |
258 | h1 = (h1 >> 6) | (h2 << 20); | |
259 | h2 = (h2 >> 12) | (h3 << 14); | |
260 | h3 = (h3 >> 18) | (h4 << 8); | |
261 | ||
262 | /* mac = (h + s) % (2^128) */ | |
fcfbeedf EB |
263 | f = (f >> 32) + h0 + dctx->s[0]; put_unaligned_le32(f, dst + 0); |
264 | f = (f >> 32) + h1 + dctx->s[1]; put_unaligned_le32(f, dst + 4); | |
265 | f = (f >> 32) + h2 + dctx->s[2]; put_unaligned_le32(f, dst + 8); | |
266 | f = (f >> 32) + h3 + dctx->s[3]; put_unaligned_le32(f, dst + 12); | |
f979e014 MW |
267 | |
268 | return 0; | |
269 | } | |
2546f811 | 270 | EXPORT_SYMBOL_GPL(crypto_poly1305_final); |
f979e014 MW |
271 | |
272 | static struct shash_alg poly1305_alg = { | |
273 | .digestsize = POLY1305_DIGEST_SIZE, | |
2546f811 MW |
274 | .init = crypto_poly1305_init, |
275 | .update = crypto_poly1305_update, | |
276 | .final = crypto_poly1305_final, | |
f979e014 MW |
277 | .descsize = sizeof(struct poly1305_desc_ctx), |
278 | .base = { | |
279 | .cra_name = "poly1305", | |
280 | .cra_driver_name = "poly1305-generic", | |
281 | .cra_priority = 100, | |
f979e014 | 282 | .cra_blocksize = POLY1305_BLOCK_SIZE, |
f979e014 MW |
283 | .cra_module = THIS_MODULE, |
284 | }, | |
285 | }; | |
286 | ||
287 | static int __init poly1305_mod_init(void) | |
288 | { | |
289 | return crypto_register_shash(&poly1305_alg); | |
290 | } | |
291 | ||
292 | static void __exit poly1305_mod_exit(void) | |
293 | { | |
294 | crypto_unregister_shash(&poly1305_alg); | |
295 | } | |
296 | ||
297 | module_init(poly1305_mod_init); | |
298 | module_exit(poly1305_mod_exit); | |
299 | ||
300 | MODULE_LICENSE("GPL"); | |
301 | MODULE_AUTHOR("Martin Willi <[email protected]>"); | |
302 | MODULE_DESCRIPTION("Poly1305 authenticator"); | |
303 | MODULE_ALIAS_CRYPTO("poly1305"); | |
304 | MODULE_ALIAS_CRYPTO("poly1305-generic"); |