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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/poly1305.h>
17#include <linux/crypto.h>
18#include <linux/kernel.h>
19#include <linux/module.h>
20
21static inline u64 mlt(u64 a, u64 b)
22{
23 return a * b;
24}
25
26static inline u32 sr(u64 v, u_char n)
27{
28 return v >> n;
29}
30
31static inline u32 and(u32 v, u32 mask)
32{
33 return v & mask;
34}
35
36static inline u32 le32_to_cpuvp(const void *p)
37{
38 return le32_to_cpup(p);
39}
40
41int crypto_poly1305_init(struct shash_desc *desc)
42{
43 struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
44
45 memset(dctx->h, 0, sizeof(dctx->h));
46 dctx->buflen = 0;
47 dctx->rset = false;
48 dctx->sset = false;
49
50 return 0;
51}
52EXPORT_SYMBOL_GPL(crypto_poly1305_init);
53
54int crypto_poly1305_setkey(struct crypto_shash *tfm,
55 const u8 *key, unsigned int keylen)
56{
57 /* Poly1305 requires a unique key for each tag, which implies that
58 * we can't set it on the tfm that gets accessed by multiple users
59 * simultaneously. Instead we expect the key as the first 32 bytes in
60 * the update() call. */
61 return -ENOTSUPP;
62}
63EXPORT_SYMBOL_GPL(crypto_poly1305_setkey);
64
65static void poly1305_setrkey(struct poly1305_desc_ctx *dctx, const u8 *key)
66{
67 /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
68 dctx->r[0] = (le32_to_cpuvp(key + 0) >> 0) & 0x3ffffff;
69 dctx->r[1] = (le32_to_cpuvp(key + 3) >> 2) & 0x3ffff03;
70 dctx->r[2] = (le32_to_cpuvp(key + 6) >> 4) & 0x3ffc0ff;
71 dctx->r[3] = (le32_to_cpuvp(key + 9) >> 6) & 0x3f03fff;
72 dctx->r[4] = (le32_to_cpuvp(key + 12) >> 8) & 0x00fffff;
73}
74
75static void poly1305_setskey(struct poly1305_desc_ctx *dctx, const u8 *key)
76{
77 dctx->s[0] = le32_to_cpuvp(key + 0);
78 dctx->s[1] = le32_to_cpuvp(key + 4);
79 dctx->s[2] = le32_to_cpuvp(key + 8);
80 dctx->s[3] = le32_to_cpuvp(key + 12);
81}
82
83unsigned int crypto_poly1305_setdesckey(struct poly1305_desc_ctx *dctx,
84 const u8 *src, unsigned int srclen)
85{
86 if (!dctx->sset) {
87 if (!dctx->rset && srclen >= POLY1305_BLOCK_SIZE) {
88 poly1305_setrkey(dctx, src);
89 src += POLY1305_BLOCK_SIZE;
90 srclen -= POLY1305_BLOCK_SIZE;
91 dctx->rset = true;
92 }
93 if (srclen >= POLY1305_BLOCK_SIZE) {
94 poly1305_setskey(dctx, src);
95 src += POLY1305_BLOCK_SIZE;
96 srclen -= POLY1305_BLOCK_SIZE;
97 dctx->sset = true;
98 }
99 }
100 return srclen;
101}
102EXPORT_SYMBOL_GPL(crypto_poly1305_setdesckey);
103
104static unsigned int poly1305_blocks(struct poly1305_desc_ctx *dctx,
105 const u8 *src, unsigned int srclen,
106 u32 hibit)
107{
108 u32 r0, r1, r2, r3, r4;
109 u32 s1, s2, s3, s4;
110 u32 h0, h1, h2, h3, h4;
111 u64 d0, d1, d2, d3, d4;
112 unsigned int datalen;
113
114 if (unlikely(!dctx->sset)) {
115 datalen = crypto_poly1305_setdesckey(dctx, src, srclen);
116 src += srclen - datalen;
117 srclen = datalen;
118 }
119
120 r0 = dctx->r[0];
121 r1 = dctx->r[1];
122 r2 = dctx->r[2];
123 r3 = dctx->r[3];
124 r4 = dctx->r[4];
125
126 s1 = r1 * 5;
127 s2 = r2 * 5;
128 s3 = r3 * 5;
129 s4 = r4 * 5;
130
131 h0 = dctx->h[0];
132 h1 = dctx->h[1];
133 h2 = dctx->h[2];
134 h3 = dctx->h[3];
135 h4 = dctx->h[4];
136
137 while (likely(srclen >= POLY1305_BLOCK_SIZE)) {
138
139 /* h += m[i] */
140 h0 += (le32_to_cpuvp(src + 0) >> 0) & 0x3ffffff;
141 h1 += (le32_to_cpuvp(src + 3) >> 2) & 0x3ffffff;
142 h2 += (le32_to_cpuvp(src + 6) >> 4) & 0x3ffffff;
143 h3 += (le32_to_cpuvp(src + 9) >> 6) & 0x3ffffff;
144 h4 += (le32_to_cpuvp(src + 12) >> 8) | hibit;
145
146 /* h *= r */
147 d0 = mlt(h0, r0) + mlt(h1, s4) + mlt(h2, s3) +
148 mlt(h3, s2) + mlt(h4, s1);
149 d1 = mlt(h0, r1) + mlt(h1, r0) + mlt(h2, s4) +
150 mlt(h3, s3) + mlt(h4, s2);
151 d2 = mlt(h0, r2) + mlt(h1, r1) + mlt(h2, r0) +
152 mlt(h3, s4) + mlt(h4, s3);
153 d3 = mlt(h0, r3) + mlt(h1, r2) + mlt(h2, r1) +
154 mlt(h3, r0) + mlt(h4, s4);
155 d4 = mlt(h0, r4) + mlt(h1, r3) + mlt(h2, r2) +
156 mlt(h3, r1) + mlt(h4, r0);
157
158 /* (partial) h %= p */
159 d1 += sr(d0, 26); h0 = and(d0, 0x3ffffff);
160 d2 += sr(d1, 26); h1 = and(d1, 0x3ffffff);
161 d3 += sr(d2, 26); h2 = and(d2, 0x3ffffff);
162 d4 += sr(d3, 26); h3 = and(d3, 0x3ffffff);
163 h0 += sr(d4, 26) * 5; h4 = and(d4, 0x3ffffff);
164 h1 += h0 >> 26; h0 = h0 & 0x3ffffff;
165
166 src += POLY1305_BLOCK_SIZE;
167 srclen -= POLY1305_BLOCK_SIZE;
168 }
169
170 dctx->h[0] = h0;
171 dctx->h[1] = h1;
172 dctx->h[2] = h2;
173 dctx->h[3] = h3;
174 dctx->h[4] = h4;
175
176 return srclen;
177}
178
179int crypto_poly1305_update(struct shash_desc *desc,
180 const u8 *src, unsigned int srclen)
181{
182 struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
183 unsigned int bytes;
184
185 if (unlikely(dctx->buflen)) {
186 bytes = min(srclen, POLY1305_BLOCK_SIZE - dctx->buflen);
187 memcpy(dctx->buf + dctx->buflen, src, bytes);
188 src += bytes;
189 srclen -= bytes;
190 dctx->buflen += bytes;
191
192 if (dctx->buflen == POLY1305_BLOCK_SIZE) {
193 poly1305_blocks(dctx, dctx->buf,
194 POLY1305_BLOCK_SIZE, 1 << 24);
195 dctx->buflen = 0;
196 }
197 }
198
199 if (likely(srclen >= POLY1305_BLOCK_SIZE)) {
200 bytes = poly1305_blocks(dctx, src, srclen, 1 << 24);
201 src += srclen - bytes;
202 srclen = bytes;
203 }
204
205 if (unlikely(srclen)) {
206 dctx->buflen = srclen;
207 memcpy(dctx->buf, src, srclen);
208 }
209
210 return 0;
211}
212EXPORT_SYMBOL_GPL(crypto_poly1305_update);
213
214int crypto_poly1305_final(struct shash_desc *desc, u8 *dst)
215{
216 struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
217 __le32 *mac = (__le32 *)dst;
218 u32 h0, h1, h2, h3, h4;
219 u32 g0, g1, g2, g3, g4;
220 u32 mask;
221 u64 f = 0;
222
223 if (unlikely(!dctx->sset))
224 return -ENOKEY;
225
226 if (unlikely(dctx->buflen)) {
227 dctx->buf[dctx->buflen++] = 1;
228 memset(dctx->buf + dctx->buflen, 0,
229 POLY1305_BLOCK_SIZE - dctx->buflen);
230 poly1305_blocks(dctx, dctx->buf, POLY1305_BLOCK_SIZE, 0);
231 }
232
233 /* fully carry h */
234 h0 = dctx->h[0];
235 h1 = dctx->h[1];
236 h2 = dctx->h[2];
237 h3 = dctx->h[3];
238 h4 = dctx->h[4];
239
240 h2 += (h1 >> 26); h1 = h1 & 0x3ffffff;
241 h3 += (h2 >> 26); h2 = h2 & 0x3ffffff;
242 h4 += (h3 >> 26); h3 = h3 & 0x3ffffff;
243 h0 += (h4 >> 26) * 5; h4 = h4 & 0x3ffffff;
244 h1 += (h0 >> 26); h0 = h0 & 0x3ffffff;
245
246 /* compute h + -p */
247 g0 = h0 + 5;
248 g1 = h1 + (g0 >> 26); g0 &= 0x3ffffff;
249 g2 = h2 + (g1 >> 26); g1 &= 0x3ffffff;
250 g3 = h3 + (g2 >> 26); g2 &= 0x3ffffff;
251 g4 = h4 + (g3 >> 26) - (1 << 26); g3 &= 0x3ffffff;
252
253 /* select h if h < p, or h + -p if h >= p */
254 mask = (g4 >> ((sizeof(u32) * 8) - 1)) - 1;
255 g0 &= mask;
256 g1 &= mask;
257 g2 &= mask;
258 g3 &= mask;
259 g4 &= mask;
260 mask = ~mask;
261 h0 = (h0 & mask) | g0;
262 h1 = (h1 & mask) | g1;
263 h2 = (h2 & mask) | g2;
264 h3 = (h3 & mask) | g3;
265 h4 = (h4 & mask) | g4;
266
267 /* h = h % (2^128) */
268 h0 = (h0 >> 0) | (h1 << 26);
269 h1 = (h1 >> 6) | (h2 << 20);
270 h2 = (h2 >> 12) | (h3 << 14);
271 h3 = (h3 >> 18) | (h4 << 8);
272
273 /* mac = (h + s) % (2^128) */
274 f = (f >> 32) + h0 + dctx->s[0]; mac[0] = cpu_to_le32(f);
275 f = (f >> 32) + h1 + dctx->s[1]; mac[1] = cpu_to_le32(f);
276 f = (f >> 32) + h2 + dctx->s[2]; mac[2] = cpu_to_le32(f);
277 f = (f >> 32) + h3 + dctx->s[3]; mac[3] = cpu_to_le32(f);
278
279 return 0;
280}
281EXPORT_SYMBOL_GPL(crypto_poly1305_final);
282
283static struct shash_alg poly1305_alg = {
284 .digestsize = POLY1305_DIGEST_SIZE,
285 .init = crypto_poly1305_init,
286 .update = crypto_poly1305_update,
287 .final = crypto_poly1305_final,
288 .setkey = crypto_poly1305_setkey,
289 .descsize = sizeof(struct poly1305_desc_ctx),
290 .base = {
291 .cra_name = "poly1305",
292 .cra_driver_name = "poly1305-generic",
293 .cra_priority = 100,
294 .cra_flags = CRYPTO_ALG_TYPE_SHASH,
295 .cra_alignmask = sizeof(u32) - 1,
296 .cra_blocksize = POLY1305_BLOCK_SIZE,
297 .cra_module = THIS_MODULE,
298 },
299};
300
301static int __init poly1305_mod_init(void)
302{
303 return crypto_register_shash(&poly1305_alg);
304}
305
306static void __exit poly1305_mod_exit(void)
307{
308 crypto_unregister_shash(&poly1305_alg);
309}
310
311module_init(poly1305_mod_init);
312module_exit(poly1305_mod_exit);
313
314MODULE_LICENSE("GPL");
315MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
316MODULE_DESCRIPTION("Poly1305 authenticator");
317MODULE_ALIAS_CRYPTO("poly1305");
318MODULE_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/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");