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 
crypto_poly1305_init(struct shash_desc * desc)22 static 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 
crypto_poly1305_setdesckey(struct poly1305_desc_ctx * dctx,const u8 * src,unsigned int srclen)34 static 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 
poly1305_blocks(struct poly1305_desc_ctx * dctx,const u8 * src,unsigned int srclen)57 static 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 
crypto_poly1305_update(struct shash_desc * desc,const u8 * src,unsigned int srclen)72 static 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 
crypto_poly1305_final(struct shash_desc * desc,u8 * dst)106 static 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 
117 static 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 
poly1305_mod_init(void)132 static int __init poly1305_mod_init(void)
133 {
134 	return crypto_register_shash(&poly1305_alg);
135 }
136 
poly1305_mod_exit(void)137 static void __exit poly1305_mod_exit(void)
138 {
139 	crypto_unregister_shash(&poly1305_alg);
140 }
141 
142 subsys_initcall(poly1305_mod_init);
143 module_exit(poly1305_mod_exit);
144 
145 MODULE_LICENSE("GPL");
146 MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
147 MODULE_DESCRIPTION("Poly1305 authenticator");
148 MODULE_ALIAS_CRYPTO("poly1305");
149 MODULE_ALIAS_CRYPTO("poly1305-generic");
150