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 | |
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(state: &dctx->h); |
27 | dctx->buflen = 0; |
28 | dctx->rset = 0; |
29 | dctx->sset = false; |
30 | |
31 | return 0; |
32 | } |
33 | |
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(key: &dctx->core_r, raw_key: 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(p: src + 0); |
46 | dctx->s[1] = get_unaligned_le32(p: src + 4); |
47 | dctx->s[2] = get_unaligned_le32(p: src + 8); |
48 | dctx->s[3] = get_unaligned_le32(p: src + 12); |
49 | src += POLY1305_BLOCK_SIZE; |
50 | srclen -= POLY1305_BLOCK_SIZE; |
51 | dctx->sset = true; |
52 | } |
53 | } |
54 | return srclen; |
55 | } |
56 | |
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(state: &dctx->h, key: &dctx->core_r, src, |
69 | nblocks: srclen / POLY1305_BLOCK_SIZE, hibit: 1); |
70 | } |
71 | |
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, src: 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 | |
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(desc: dctx, digest: 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 | |
132 | static int __init poly1305_mod_init(void) |
133 | { |
134 | return crypto_register_shash(alg: &poly1305_alg); |
135 | } |
136 | |
137 | static void __exit poly1305_mod_exit(void) |
138 | { |
139 | crypto_unregister_shash(alg: &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 | |