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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 | ||
1b6fd3d5 | 41 | poly1305_core_init(&dctx->h); |
f979e014 | 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 | |
1b6fd3d5 | 50 | void poly1305_core_setkey(struct poly1305_key *key, const u8 *raw_key) |
c2b7b20a | 51 | { |
f979e014 | 52 | /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */ |
1b6fd3d5 EB |
53 | key->r[0] = (get_unaligned_le32(raw_key + 0) >> 0) & 0x3ffffff; |
54 | key->r[1] = (get_unaligned_le32(raw_key + 3) >> 2) & 0x3ffff03; | |
55 | key->r[2] = (get_unaligned_le32(raw_key + 6) >> 4) & 0x3ffc0ff; | |
56 | key->r[3] = (get_unaligned_le32(raw_key + 9) >> 6) & 0x3f03fff; | |
57 | key->r[4] = (get_unaligned_le32(raw_key + 12) >> 8) & 0x00fffff; | |
f979e014 | 58 | } |
1b6fd3d5 | 59 | EXPORT_SYMBOL_GPL(poly1305_core_setkey); |
f979e014 | 60 | |
a16e772e EB |
61 | /* |
62 | * Poly1305 requires a unique key for each tag, which implies that we can't set | |
63 | * it on the tfm that gets accessed by multiple users simultaneously. Instead we | |
64 | * expect the key as the first 32 bytes in the update() call. | |
65 | */ | |
2546f811 MW |
66 | unsigned int crypto_poly1305_setdesckey(struct poly1305_desc_ctx *dctx, |
67 | const u8 *src, unsigned int srclen) | |
f979e014 | 68 | { |
2546f811 | 69 | if (!dctx->sset) { |
c2b7b20a | 70 | if (!dctx->rset && srclen >= POLY1305_BLOCK_SIZE) { |
1b6fd3d5 | 71 | poly1305_core_setkey(&dctx->r, src); |
c2b7b20a MW |
72 | src += POLY1305_BLOCK_SIZE; |
73 | srclen -= POLY1305_BLOCK_SIZE; | |
74 | dctx->rset = true; | |
75 | } | |
76 | if (srclen >= POLY1305_BLOCK_SIZE) { | |
1b6fd3d5 EB |
77 | dctx->s[0] = get_unaligned_le32(src + 0); |
78 | dctx->s[1] = get_unaligned_le32(src + 4); | |
79 | dctx->s[2] = get_unaligned_le32(src + 8); | |
80 | dctx->s[3] = get_unaligned_le32(src + 12); | |
c2b7b20a MW |
81 | src += POLY1305_BLOCK_SIZE; |
82 | srclen -= POLY1305_BLOCK_SIZE; | |
83 | dctx->sset = true; | |
84 | } | |
85 | } | |
2546f811 MW |
86 | return srclen; |
87 | } | |
88 | EXPORT_SYMBOL_GPL(crypto_poly1305_setdesckey); | |
89 | ||
1b6fd3d5 EB |
90 | static void poly1305_blocks_internal(struct poly1305_state *state, |
91 | const struct poly1305_key *key, | |
92 | const void *src, unsigned int nblocks, | |
93 | u32 hibit) | |
2546f811 MW |
94 | { |
95 | u32 r0, r1, r2, r3, r4; | |
96 | u32 s1, s2, s3, s4; | |
97 | u32 h0, h1, h2, h3, h4; | |
98 | u64 d0, d1, d2, d3, d4; | |
2546f811 | 99 | |
1b6fd3d5 EB |
100 | if (!nblocks) |
101 | return; | |
c2b7b20a | 102 | |
1b6fd3d5 EB |
103 | r0 = key->r[0]; |
104 | r1 = key->r[1]; | |
105 | r2 = key->r[2]; | |
106 | r3 = key->r[3]; | |
107 | r4 = key->r[4]; | |
f979e014 MW |
108 | |
109 | s1 = r1 * 5; | |
110 | s2 = r2 * 5; | |
111 | s3 = r3 * 5; | |
112 | s4 = r4 * 5; | |
113 | ||
1b6fd3d5 EB |
114 | h0 = state->h[0]; |
115 | h1 = state->h[1]; | |
116 | h2 = state->h[2]; | |
117 | h3 = state->h[3]; | |
118 | h4 = state->h[4]; | |
f979e014 | 119 | |
1b6fd3d5 | 120 | do { |
f979e014 | 121 | /* h += m[i] */ |
109e23bd JD |
122 | h0 += (get_unaligned_le32(src + 0) >> 0) & 0x3ffffff; |
123 | h1 += (get_unaligned_le32(src + 3) >> 2) & 0x3ffffff; | |
124 | h2 += (get_unaligned_le32(src + 6) >> 4) & 0x3ffffff; | |
125 | h3 += (get_unaligned_le32(src + 9) >> 6) & 0x3ffffff; | |
126 | h4 += (get_unaligned_le32(src + 12) >> 8) | hibit; | |
f979e014 MW |
127 | |
128 | /* h *= r */ | |
129 | d0 = mlt(h0, r0) + mlt(h1, s4) + mlt(h2, s3) + | |
130 | mlt(h3, s2) + mlt(h4, s1); | |
131 | d1 = mlt(h0, r1) + mlt(h1, r0) + mlt(h2, s4) + | |
132 | mlt(h3, s3) + mlt(h4, s2); | |
133 | d2 = mlt(h0, r2) + mlt(h1, r1) + mlt(h2, r0) + | |
134 | mlt(h3, s4) + mlt(h4, s3); | |
135 | d3 = mlt(h0, r3) + mlt(h1, r2) + mlt(h2, r1) + | |
136 | mlt(h3, r0) + mlt(h4, s4); | |
137 | d4 = mlt(h0, r4) + mlt(h1, r3) + mlt(h2, r2) + | |
138 | mlt(h3, r1) + mlt(h4, r0); | |
139 | ||
140 | /* (partial) h %= p */ | |
141 | d1 += sr(d0, 26); h0 = and(d0, 0x3ffffff); | |
142 | d2 += sr(d1, 26); h1 = and(d1, 0x3ffffff); | |
143 | d3 += sr(d2, 26); h2 = and(d2, 0x3ffffff); | |
144 | d4 += sr(d3, 26); h3 = and(d3, 0x3ffffff); | |
145 | h0 += sr(d4, 26) * 5; h4 = and(d4, 0x3ffffff); | |
146 | h1 += h0 >> 26; h0 = h0 & 0x3ffffff; | |
147 | ||
148 | src += POLY1305_BLOCK_SIZE; | |
1b6fd3d5 | 149 | } while (--nblocks); |
f979e014 | 150 | |
1b6fd3d5 EB |
151 | state->h[0] = h0; |
152 | state->h[1] = h1; | |
153 | state->h[2] = h2; | |
154 | state->h[3] = h3; | |
155 | state->h[4] = h4; | |
156 | } | |
f979e014 | 157 | |
1b6fd3d5 EB |
158 | void poly1305_core_blocks(struct poly1305_state *state, |
159 | const struct poly1305_key *key, | |
160 | const void *src, unsigned int nblocks) | |
161 | { | |
162 | poly1305_blocks_internal(state, key, src, nblocks, 1 << 24); | |
163 | } | |
164 | EXPORT_SYMBOL_GPL(poly1305_core_blocks); | |
165 | ||
166 | static void poly1305_blocks(struct poly1305_desc_ctx *dctx, | |
167 | const u8 *src, unsigned int srclen, u32 hibit) | |
168 | { | |
169 | unsigned int datalen; | |
170 | ||
171 | if (unlikely(!dctx->sset)) { | |
172 | datalen = crypto_poly1305_setdesckey(dctx, src, srclen); | |
173 | src += srclen - datalen; | |
174 | srclen = datalen; | |
175 | } | |
176 | ||
177 | poly1305_blocks_internal(&dctx->h, &dctx->r, | |
178 | src, srclen / POLY1305_BLOCK_SIZE, hibit); | |
f979e014 MW |
179 | } |
180 | ||
2546f811 | 181 | int crypto_poly1305_update(struct shash_desc *desc, |
f979e014 MW |
182 | const u8 *src, unsigned int srclen) |
183 | { | |
184 | struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc); | |
f979e014 MW |
185 | unsigned int bytes; |
186 | ||
187 | if (unlikely(dctx->buflen)) { | |
188 | bytes = min(srclen, POLY1305_BLOCK_SIZE - dctx->buflen); | |
189 | memcpy(dctx->buf + dctx->buflen, src, bytes); | |
190 | src += bytes; | |
191 | srclen -= bytes; | |
192 | dctx->buflen += bytes; | |
193 | ||
194 | if (dctx->buflen == POLY1305_BLOCK_SIZE) { | |
c2b7b20a | 195 | poly1305_blocks(dctx, dctx->buf, |
f979e014 MW |
196 | POLY1305_BLOCK_SIZE, 1 << 24); |
197 | dctx->buflen = 0; | |
198 | } | |
199 | } | |
200 | ||
201 | if (likely(srclen >= POLY1305_BLOCK_SIZE)) { | |
1b6fd3d5 EB |
202 | poly1305_blocks(dctx, src, srclen, 1 << 24); |
203 | src += srclen - (srclen % POLY1305_BLOCK_SIZE); | |
204 | srclen %= POLY1305_BLOCK_SIZE; | |
f979e014 MW |
205 | } |
206 | ||
207 | if (unlikely(srclen)) { | |
208 | dctx->buflen = srclen; | |
209 | memcpy(dctx->buf, src, srclen); | |
210 | } | |
211 | ||
212 | return 0; | |
213 | } | |
2546f811 | 214 | EXPORT_SYMBOL_GPL(crypto_poly1305_update); |
f979e014 | 215 | |
1b6fd3d5 | 216 | void poly1305_core_emit(const struct poly1305_state *state, void *dst) |
f979e014 | 217 | { |
f979e014 MW |
218 | u32 h0, h1, h2, h3, h4; |
219 | u32 g0, g1, g2, g3, g4; | |
220 | u32 mask; | |
f979e014 MW |
221 | |
222 | /* fully carry h */ | |
1b6fd3d5 EB |
223 | h0 = state->h[0]; |
224 | h1 = state->h[1]; | |
225 | h2 = state->h[2]; | |
226 | h3 = state->h[3]; | |
227 | h4 = state->h[4]; | |
f979e014 MW |
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) */ | |
1b6fd3d5 EB |
257 | put_unaligned_le32((h0 >> 0) | (h1 << 26), dst + 0); |
258 | put_unaligned_le32((h1 >> 6) | (h2 << 20), dst + 4); | |
259 | put_unaligned_le32((h2 >> 12) | (h3 << 14), dst + 8); | |
260 | put_unaligned_le32((h3 >> 18) | (h4 << 8), dst + 12); | |
261 | } | |
262 | EXPORT_SYMBOL_GPL(poly1305_core_emit); | |
263 | ||
264 | int crypto_poly1305_final(struct shash_desc *desc, u8 *dst) | |
265 | { | |
266 | struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc); | |
267 | __le32 digest[4]; | |
268 | u64 f = 0; | |
269 | ||
270 | if (unlikely(!dctx->sset)) | |
271 | return -ENOKEY; | |
272 | ||
273 | if (unlikely(dctx->buflen)) { | |
274 | dctx->buf[dctx->buflen++] = 1; | |
275 | memset(dctx->buf + dctx->buflen, 0, | |
276 | POLY1305_BLOCK_SIZE - dctx->buflen); | |
277 | poly1305_blocks(dctx, dctx->buf, POLY1305_BLOCK_SIZE, 0); | |
278 | } | |
279 | ||
280 | poly1305_core_emit(&dctx->h, digest); | |
f979e014 MW |
281 | |
282 | /* mac = (h + s) % (2^128) */ | |
1b6fd3d5 EB |
283 | f = (f >> 32) + le32_to_cpu(digest[0]) + dctx->s[0]; |
284 | put_unaligned_le32(f, dst + 0); | |
285 | f = (f >> 32) + le32_to_cpu(digest[1]) + dctx->s[1]; | |
286 | put_unaligned_le32(f, dst + 4); | |
287 | f = (f >> 32) + le32_to_cpu(digest[2]) + dctx->s[2]; | |
288 | put_unaligned_le32(f, dst + 8); | |
289 | f = (f >> 32) + le32_to_cpu(digest[3]) + dctx->s[3]; | |
290 | put_unaligned_le32(f, dst + 12); | |
f979e014 MW |
291 | |
292 | return 0; | |
293 | } | |
2546f811 | 294 | EXPORT_SYMBOL_GPL(crypto_poly1305_final); |
f979e014 MW |
295 | |
296 | static struct shash_alg poly1305_alg = { | |
297 | .digestsize = POLY1305_DIGEST_SIZE, | |
2546f811 MW |
298 | .init = crypto_poly1305_init, |
299 | .update = crypto_poly1305_update, | |
300 | .final = crypto_poly1305_final, | |
f979e014 MW |
301 | .descsize = sizeof(struct poly1305_desc_ctx), |
302 | .base = { | |
303 | .cra_name = "poly1305", | |
304 | .cra_driver_name = "poly1305-generic", | |
305 | .cra_priority = 100, | |
f979e014 | 306 | .cra_blocksize = POLY1305_BLOCK_SIZE, |
f979e014 MW |
307 | .cra_module = THIS_MODULE, |
308 | }, | |
309 | }; | |
310 | ||
311 | static int __init poly1305_mod_init(void) | |
312 | { | |
313 | return crypto_register_shash(&poly1305_alg); | |
314 | } | |
315 | ||
316 | static void __exit poly1305_mod_exit(void) | |
317 | { | |
318 | crypto_unregister_shash(&poly1305_alg); | |
319 | } | |
320 | ||
321 | module_init(poly1305_mod_init); | |
322 | module_exit(poly1305_mod_exit); | |
323 | ||
324 | MODULE_LICENSE("GPL"); | |
325 | MODULE_AUTHOR("Martin Willi <martin@strongswan.org>"); | |
326 | MODULE_DESCRIPTION("Poly1305 authenticator"); | |
327 | MODULE_ALIAS_CRYPTO("poly1305"); | |
328 | MODULE_ALIAS_CRYPTO("poly1305-generic"); |