blob: b60c1eee9839feae1765d7b0dd559c9a265ed341
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> |
16 | #include <crypto/poly1305.h> |
17 | #include <linux/crypto.h> |
18 | #include <linux/kernel.h> |
19 | #include <linux/module.h> |
20 | #include <asm/unaligned.h> |
21 | |
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 | |
37 | int crypto_poly1305_init(struct shash_desc *desc) |
38 | { |
39 | struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc); |
40 | |
41 | poly1305_core_init(&dctx->h); |
42 | dctx->buflen = 0; |
43 | dctx->rset = false; |
44 | dctx->sset = false; |
45 | |
46 | return 0; |
47 | } |
48 | EXPORT_SYMBOL_GPL(crypto_poly1305_init); |
49 | |
50 | void poly1305_core_setkey(struct poly1305_key *key, const u8 *raw_key) |
51 | { |
52 | /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */ |
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; |
58 | } |
59 | EXPORT_SYMBOL_GPL(poly1305_core_setkey); |
60 | |
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 | */ |
66 | unsigned int crypto_poly1305_setdesckey(struct poly1305_desc_ctx *dctx, |
67 | const u8 *src, unsigned int srclen) |
68 | { |
69 | if (!dctx->sset) { |
70 | if (!dctx->rset && srclen >= POLY1305_BLOCK_SIZE) { |
71 | poly1305_core_setkey(&dctx->r, src); |
72 | src += POLY1305_BLOCK_SIZE; |
73 | srclen -= POLY1305_BLOCK_SIZE; |
74 | dctx->rset = true; |
75 | } |
76 | if (srclen >= POLY1305_BLOCK_SIZE) { |
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); |
81 | src += POLY1305_BLOCK_SIZE; |
82 | srclen -= POLY1305_BLOCK_SIZE; |
83 | dctx->sset = true; |
84 | } |
85 | } |
86 | return srclen; |
87 | } |
88 | EXPORT_SYMBOL_GPL(crypto_poly1305_setdesckey); |
89 | |
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) |
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; |
99 | |
100 | if (!nblocks) |
101 | return; |
102 | |
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]; |
108 | |
109 | s1 = r1 * 5; |
110 | s2 = r2 * 5; |
111 | s3 = r3 * 5; |
112 | s4 = r4 * 5; |
113 | |
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]; |
119 | |
120 | do { |
121 | /* h += m[i] */ |
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; |
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; |
149 | } while (--nblocks); |
150 | |
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 | } |
157 | |
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); |
179 | } |
180 | |
181 | int crypto_poly1305_update(struct shash_desc *desc, |
182 | const u8 *src, unsigned int srclen) |
183 | { |
184 | struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc); |
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) { |
195 | poly1305_blocks(dctx, dctx->buf, |
196 | POLY1305_BLOCK_SIZE, 1 << 24); |
197 | dctx->buflen = 0; |
198 | } |
199 | } |
200 | |
201 | if (likely(srclen >= POLY1305_BLOCK_SIZE)) { |
202 | poly1305_blocks(dctx, src, srclen, 1 << 24); |
203 | src += srclen - (srclen % POLY1305_BLOCK_SIZE); |
204 | srclen %= POLY1305_BLOCK_SIZE; |
205 | } |
206 | |
207 | if (unlikely(srclen)) { |
208 | dctx->buflen = srclen; |
209 | memcpy(dctx->buf, src, srclen); |
210 | } |
211 | |
212 | return 0; |
213 | } |
214 | EXPORT_SYMBOL_GPL(crypto_poly1305_update); |
215 | |
216 | void poly1305_core_emit(const struct poly1305_state *state, void *dst) |
217 | { |
218 | u32 h0, h1, h2, h3, h4; |
219 | u32 g0, g1, g2, g3, g4; |
220 | u32 mask; |
221 | |
222 | /* fully carry h */ |
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]; |
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 | 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); |
281 | |
282 | /* mac = (h + s) % (2^128) */ |
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); |
291 | |
292 | return 0; |
293 | } |
294 | EXPORT_SYMBOL_GPL(crypto_poly1305_final); |
295 | |
296 | static struct shash_alg poly1305_alg = { |
297 | .digestsize = POLY1305_DIGEST_SIZE, |
298 | .init = crypto_poly1305_init, |
299 | .update = crypto_poly1305_update, |
300 | .final = crypto_poly1305_final, |
301 | .descsize = sizeof(struct poly1305_desc_ctx), |
302 | .base = { |
303 | .cra_name = "poly1305", |
304 | .cra_driver_name = "poly1305-generic", |
305 | .cra_priority = 100, |
306 | .cra_flags = CRYPTO_ALG_TYPE_SHASH, |
307 | .cra_alignmask = sizeof(u32) - 1, |
308 | .cra_blocksize = POLY1305_BLOCK_SIZE, |
309 | .cra_module = THIS_MODULE, |
310 | }, |
311 | }; |
312 | |
313 | static int __init poly1305_mod_init(void) |
314 | { |
315 | return crypto_register_shash(&poly1305_alg); |
316 | } |
317 | |
318 | static void __exit poly1305_mod_exit(void) |
319 | { |
320 | crypto_unregister_shash(&poly1305_alg); |
321 | } |
322 | |
323 | module_init(poly1305_mod_init); |
324 | module_exit(poly1305_mod_exit); |
325 | |
326 | MODULE_LICENSE("GPL"); |
327 | MODULE_AUTHOR("Martin Willi <martin@strongswan.org>"); |
328 | MODULE_DESCRIPTION("Poly1305 authenticator"); |
329 | MODULE_ALIAS_CRYPTO("poly1305"); |
330 | MODULE_ALIAS_CRYPTO("poly1305-generic"); |
331 |