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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/internal/poly1305.h>
17#include <linux/crypto.h>
18#include <linux/kernel.h>
19#include <linux/module.h>
20#include <asm/unaligned.h>
21
22static int crypto_poly1305_init(struct shash_desc *desc)
23{
24 struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
25
26 poly1305_core_init(&dctx->h);
27 dctx->buflen = 0;
28 dctx->rset = 0;
29 dctx->sset = false;
30
31 return 0;
32}
33
34static unsigned int crypto_poly1305_setdesckey(struct poly1305_desc_ctx *dctx,
35 const u8 *src, unsigned int srclen)
36{
37 if (!dctx->sset) {
38 if (!dctx->rset && srclen >= POLY1305_BLOCK_SIZE) {
39 poly1305_core_setkey(&dctx->core_r, src);
40 src += POLY1305_BLOCK_SIZE;
41 srclen -= POLY1305_BLOCK_SIZE;
42 dctx->rset = 2;
43 }
44 if (srclen >= POLY1305_BLOCK_SIZE) {
45 dctx->s[0] = get_unaligned_le32(src + 0);
46 dctx->s[1] = get_unaligned_le32(src + 4);
47 dctx->s[2] = get_unaligned_le32(src + 8);
48 dctx->s[3] = get_unaligned_le32(src + 12);
49 src += POLY1305_BLOCK_SIZE;
50 srclen -= POLY1305_BLOCK_SIZE;
51 dctx->sset = true;
52 }
53 }
54 return srclen;
55}
56
57static void poly1305_blocks(struct poly1305_desc_ctx *dctx, const u8 *src,
58 unsigned int srclen)
59{
60 unsigned int datalen;
61
62 if (unlikely(!dctx->sset)) {
63 datalen = crypto_poly1305_setdesckey(dctx, src, srclen);
64 src += srclen - datalen;
65 srclen = datalen;
66 }
67
68 poly1305_core_blocks(&dctx->h, &dctx->core_r, src,
69 srclen / POLY1305_BLOCK_SIZE, 1);
70}
71
72static int crypto_poly1305_update(struct shash_desc *desc,
73 const u8 *src, unsigned int srclen)
74{
75 struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
76 unsigned int bytes;
77
78 if (unlikely(dctx->buflen)) {
79 bytes = min(srclen, POLY1305_BLOCK_SIZE - dctx->buflen);
80 memcpy(dctx->buf + dctx->buflen, src, bytes);
81 src += bytes;
82 srclen -= bytes;
83 dctx->buflen += bytes;
84
85 if (dctx->buflen == POLY1305_BLOCK_SIZE) {
86 poly1305_blocks(dctx, dctx->buf,
87 POLY1305_BLOCK_SIZE);
88 dctx->buflen = 0;
89 }
90 }
91
92 if (likely(srclen >= POLY1305_BLOCK_SIZE)) {
93 poly1305_blocks(dctx, src, srclen);
94 src += srclen - (srclen % POLY1305_BLOCK_SIZE);
95 srclen %= POLY1305_BLOCK_SIZE;
96 }
97
98 if (unlikely(srclen)) {
99 dctx->buflen = srclen;
100 memcpy(dctx->buf, src, srclen);
101 }
102
103 return 0;
104}
105
106static int crypto_poly1305_final(struct shash_desc *desc, u8 *dst)
107{
108 struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
109
110 if (unlikely(!dctx->sset))
111 return -ENOKEY;
112
113 poly1305_final_generic(dctx, dst);
114 return 0;
115}
116
117static struct shash_alg poly1305_alg = {
118 .digestsize = POLY1305_DIGEST_SIZE,
119 .init = crypto_poly1305_init,
120 .update = crypto_poly1305_update,
121 .final = crypto_poly1305_final,
122 .descsize = sizeof(struct poly1305_desc_ctx),
123 .base = {
124 .cra_name = "poly1305",
125 .cra_driver_name = "poly1305-generic",
126 .cra_priority = 100,
127 .cra_blocksize = POLY1305_BLOCK_SIZE,
128 .cra_module = THIS_MODULE,
129 },
130};
131
132static int __init poly1305_mod_init(void)
133{
134 return crypto_register_shash(&poly1305_alg);
135}
136
137static void __exit poly1305_mod_exit(void)
138{
139 crypto_unregister_shash(&poly1305_alg);
140}
141
142subsys_initcall(poly1305_mod_init);
143module_exit(poly1305_mod_exit);
144
145MODULE_LICENSE("GPL");
146MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
147MODULE_DESCRIPTION("Poly1305 authenticator");
148MODULE_ALIAS_CRYPTO("poly1305");
149MODULE_ALIAS_CRYPTO("poly1305-generic");
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
22static inline u64 mlt(u64 a, u64 b)
23{
24 return a * b;
25}
26
27static inline u32 sr(u64 v, u_char n)
28{
29 return v >> n;
30}
31
32static inline u32 and(u32 v, u32 mask)
33{
34 return v & mask;
35}
36
37int crypto_poly1305_init(struct shash_desc *desc)
38{
39 struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
40
41 memset(dctx->h, 0, sizeof(dctx->h));
42 dctx->buflen = 0;
43 dctx->rset = false;
44 dctx->sset = false;
45
46 return 0;
47}
48EXPORT_SYMBOL_GPL(crypto_poly1305_init);
49
50int crypto_poly1305_setkey(struct crypto_shash *tfm,
51 const u8 *key, unsigned int keylen)
52{
53 /* Poly1305 requires a unique key for each tag, which implies that
54 * we can't set it on the tfm that gets accessed by multiple users
55 * simultaneously. Instead we expect the key as the first 32 bytes in
56 * the update() call. */
57 return -ENOTSUPP;
58}
59EXPORT_SYMBOL_GPL(crypto_poly1305_setkey);
60
61static void poly1305_setrkey(struct poly1305_desc_ctx *dctx, const u8 *key)
62{
63 /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
64 dctx->r[0] = (get_unaligned_le32(key + 0) >> 0) & 0x3ffffff;
65 dctx->r[1] = (get_unaligned_le32(key + 3) >> 2) & 0x3ffff03;
66 dctx->r[2] = (get_unaligned_le32(key + 6) >> 4) & 0x3ffc0ff;
67 dctx->r[3] = (get_unaligned_le32(key + 9) >> 6) & 0x3f03fff;
68 dctx->r[4] = (get_unaligned_le32(key + 12) >> 8) & 0x00fffff;
69}
70
71static void poly1305_setskey(struct poly1305_desc_ctx *dctx, const u8 *key)
72{
73 dctx->s[0] = get_unaligned_le32(key + 0);
74 dctx->s[1] = get_unaligned_le32(key + 4);
75 dctx->s[2] = get_unaligned_le32(key + 8);
76 dctx->s[3] = get_unaligned_le32(key + 12);
77}
78
79unsigned int crypto_poly1305_setdesckey(struct poly1305_desc_ctx *dctx,
80 const u8 *src, unsigned int srclen)
81{
82 if (!dctx->sset) {
83 if (!dctx->rset && srclen >= POLY1305_BLOCK_SIZE) {
84 poly1305_setrkey(dctx, src);
85 src += POLY1305_BLOCK_SIZE;
86 srclen -= POLY1305_BLOCK_SIZE;
87 dctx->rset = true;
88 }
89 if (srclen >= POLY1305_BLOCK_SIZE) {
90 poly1305_setskey(dctx, src);
91 src += POLY1305_BLOCK_SIZE;
92 srclen -= POLY1305_BLOCK_SIZE;
93 dctx->sset = true;
94 }
95 }
96 return srclen;
97}
98EXPORT_SYMBOL_GPL(crypto_poly1305_setdesckey);
99
100static unsigned int poly1305_blocks(struct poly1305_desc_ctx *dctx,
101 const u8 *src, unsigned int srclen,
102 u32 hibit)
103{
104 u32 r0, r1, r2, r3, r4;
105 u32 s1, s2, s3, s4;
106 u32 h0, h1, h2, h3, h4;
107 u64 d0, d1, d2, d3, d4;
108 unsigned int datalen;
109
110 if (unlikely(!dctx->sset)) {
111 datalen = crypto_poly1305_setdesckey(dctx, src, srclen);
112 src += srclen - datalen;
113 srclen = datalen;
114 }
115
116 r0 = dctx->r[0];
117 r1 = dctx->r[1];
118 r2 = dctx->r[2];
119 r3 = dctx->r[3];
120 r4 = dctx->r[4];
121
122 s1 = r1 * 5;
123 s2 = r2 * 5;
124 s3 = r3 * 5;
125 s4 = r4 * 5;
126
127 h0 = dctx->h[0];
128 h1 = dctx->h[1];
129 h2 = dctx->h[2];
130 h3 = dctx->h[3];
131 h4 = dctx->h[4];
132
133 while (likely(srclen >= POLY1305_BLOCK_SIZE)) {
134
135 /* h += m[i] */
136 h0 += (get_unaligned_le32(src + 0) >> 0) & 0x3ffffff;
137 h1 += (get_unaligned_le32(src + 3) >> 2) & 0x3ffffff;
138 h2 += (get_unaligned_le32(src + 6) >> 4) & 0x3ffffff;
139 h3 += (get_unaligned_le32(src + 9) >> 6) & 0x3ffffff;
140 h4 += (get_unaligned_le32(src + 12) >> 8) | hibit;
141
142 /* h *= r */
143 d0 = mlt(h0, r0) + mlt(h1, s4) + mlt(h2, s3) +
144 mlt(h3, s2) + mlt(h4, s1);
145 d1 = mlt(h0, r1) + mlt(h1, r0) + mlt(h2, s4) +
146 mlt(h3, s3) + mlt(h4, s2);
147 d2 = mlt(h0, r2) + mlt(h1, r1) + mlt(h2, r0) +
148 mlt(h3, s4) + mlt(h4, s3);
149 d3 = mlt(h0, r3) + mlt(h1, r2) + mlt(h2, r1) +
150 mlt(h3, r0) + mlt(h4, s4);
151 d4 = mlt(h0, r4) + mlt(h1, r3) + mlt(h2, r2) +
152 mlt(h3, r1) + mlt(h4, r0);
153
154 /* (partial) h %= p */
155 d1 += sr(d0, 26); h0 = and(d0, 0x3ffffff);
156 d2 += sr(d1, 26); h1 = and(d1, 0x3ffffff);
157 d3 += sr(d2, 26); h2 = and(d2, 0x3ffffff);
158 d4 += sr(d3, 26); h3 = and(d3, 0x3ffffff);
159 h0 += sr(d4, 26) * 5; h4 = and(d4, 0x3ffffff);
160 h1 += h0 >> 26; h0 = h0 & 0x3ffffff;
161
162 src += POLY1305_BLOCK_SIZE;
163 srclen -= POLY1305_BLOCK_SIZE;
164 }
165
166 dctx->h[0] = h0;
167 dctx->h[1] = h1;
168 dctx->h[2] = h2;
169 dctx->h[3] = h3;
170 dctx->h[4] = h4;
171
172 return srclen;
173}
174
175int crypto_poly1305_update(struct shash_desc *desc,
176 const u8 *src, unsigned int srclen)
177{
178 struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
179 unsigned int bytes;
180
181 if (unlikely(dctx->buflen)) {
182 bytes = min(srclen, POLY1305_BLOCK_SIZE - dctx->buflen);
183 memcpy(dctx->buf + dctx->buflen, src, bytes);
184 src += bytes;
185 srclen -= bytes;
186 dctx->buflen += bytes;
187
188 if (dctx->buflen == POLY1305_BLOCK_SIZE) {
189 poly1305_blocks(dctx, dctx->buf,
190 POLY1305_BLOCK_SIZE, 1 << 24);
191 dctx->buflen = 0;
192 }
193 }
194
195 if (likely(srclen >= POLY1305_BLOCK_SIZE)) {
196 bytes = poly1305_blocks(dctx, src, srclen, 1 << 24);
197 src += srclen - bytes;
198 srclen = bytes;
199 }
200
201 if (unlikely(srclen)) {
202 dctx->buflen = srclen;
203 memcpy(dctx->buf, src, srclen);
204 }
205
206 return 0;
207}
208EXPORT_SYMBOL_GPL(crypto_poly1305_update);
209
210int crypto_poly1305_final(struct shash_desc *desc, u8 *dst)
211{
212 struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
213 __le32 *mac = (__le32 *)dst;
214 u32 h0, h1, h2, h3, h4;
215 u32 g0, g1, g2, g3, g4;
216 u32 mask;
217 u64 f = 0;
218
219 if (unlikely(!dctx->sset))
220 return -ENOKEY;
221
222 if (unlikely(dctx->buflen)) {
223 dctx->buf[dctx->buflen++] = 1;
224 memset(dctx->buf + dctx->buflen, 0,
225 POLY1305_BLOCK_SIZE - dctx->buflen);
226 poly1305_blocks(dctx, dctx->buf, POLY1305_BLOCK_SIZE, 0);
227 }
228
229 /* fully carry h */
230 h0 = dctx->h[0];
231 h1 = dctx->h[1];
232 h2 = dctx->h[2];
233 h3 = dctx->h[3];
234 h4 = dctx->h[4];
235
236 h2 += (h1 >> 26); h1 = h1 & 0x3ffffff;
237 h3 += (h2 >> 26); h2 = h2 & 0x3ffffff;
238 h4 += (h3 >> 26); h3 = h3 & 0x3ffffff;
239 h0 += (h4 >> 26) * 5; h4 = h4 & 0x3ffffff;
240 h1 += (h0 >> 26); h0 = h0 & 0x3ffffff;
241
242 /* compute h + -p */
243 g0 = h0 + 5;
244 g1 = h1 + (g0 >> 26); g0 &= 0x3ffffff;
245 g2 = h2 + (g1 >> 26); g1 &= 0x3ffffff;
246 g3 = h3 + (g2 >> 26); g2 &= 0x3ffffff;
247 g4 = h4 + (g3 >> 26) - (1 << 26); g3 &= 0x3ffffff;
248
249 /* select h if h < p, or h + -p if h >= p */
250 mask = (g4 >> ((sizeof(u32) * 8) - 1)) - 1;
251 g0 &= mask;
252 g1 &= mask;
253 g2 &= mask;
254 g3 &= mask;
255 g4 &= mask;
256 mask = ~mask;
257 h0 = (h0 & mask) | g0;
258 h1 = (h1 & mask) | g1;
259 h2 = (h2 & mask) | g2;
260 h3 = (h3 & mask) | g3;
261 h4 = (h4 & mask) | g4;
262
263 /* h = h % (2^128) */
264 h0 = (h0 >> 0) | (h1 << 26);
265 h1 = (h1 >> 6) | (h2 << 20);
266 h2 = (h2 >> 12) | (h3 << 14);
267 h3 = (h3 >> 18) | (h4 << 8);
268
269 /* mac = (h + s) % (2^128) */
270 f = (f >> 32) + h0 + dctx->s[0]; mac[0] = cpu_to_le32(f);
271 f = (f >> 32) + h1 + dctx->s[1]; mac[1] = cpu_to_le32(f);
272 f = (f >> 32) + h2 + dctx->s[2]; mac[2] = cpu_to_le32(f);
273 f = (f >> 32) + h3 + dctx->s[3]; mac[3] = cpu_to_le32(f);
274
275 return 0;
276}
277EXPORT_SYMBOL_GPL(crypto_poly1305_final);
278
279static struct shash_alg poly1305_alg = {
280 .digestsize = POLY1305_DIGEST_SIZE,
281 .init = crypto_poly1305_init,
282 .update = crypto_poly1305_update,
283 .final = crypto_poly1305_final,
284 .setkey = crypto_poly1305_setkey,
285 .descsize = sizeof(struct poly1305_desc_ctx),
286 .base = {
287 .cra_name = "poly1305",
288 .cra_driver_name = "poly1305-generic",
289 .cra_priority = 100,
290 .cra_flags = CRYPTO_ALG_TYPE_SHASH,
291 .cra_alignmask = sizeof(u32) - 1,
292 .cra_blocksize = POLY1305_BLOCK_SIZE,
293 .cra_module = THIS_MODULE,
294 },
295};
296
297static int __init poly1305_mod_init(void)
298{
299 return crypto_register_shash(&poly1305_alg);
300}
301
302static void __exit poly1305_mod_exit(void)
303{
304 crypto_unregister_shash(&poly1305_alg);
305}
306
307module_init(poly1305_mod_init);
308module_exit(poly1305_mod_exit);
309
310MODULE_LICENSE("GPL");
311MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
312MODULE_DESCRIPTION("Poly1305 authenticator");
313MODULE_ALIAS_CRYPTO("poly1305");
314MODULE_ALIAS_CRYPTO("poly1305-generic");