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1 | /* |
2 | * GHASH: digest algorithm for GCM (Galois/Counter Mode). | |
3 | * | |
4 | * Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <mh1@iki.fi> | |
5 | * Copyright (c) 2009 Intel Corp. | |
6 | * Author: Huang Ying <ying.huang@intel.com> | |
7 | * | |
8 | * The algorithm implementation is copied from gcm.c. | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or modify it | |
11 | * under the terms of the GNU General Public License version 2 as published | |
12 | * by the Free Software Foundation. | |
13 | */ | |
14 | ||
15 | #include <crypto/algapi.h> | |
16 | #include <crypto/gf128mul.h> | |
17 | #include <crypto/internal/hash.h> | |
18 | #include <linux/crypto.h> | |
19 | #include <linux/init.h> | |
20 | #include <linux/kernel.h> | |
21 | #include <linux/module.h> | |
22 | ||
23 | #define GHASH_BLOCK_SIZE 16 | |
24 | #define GHASH_DIGEST_SIZE 16 | |
25 | ||
26 | struct ghash_ctx { | |
27 | struct gf128mul_4k *gf128; | |
28 | }; | |
29 | ||
30 | struct ghash_desc_ctx { | |
31 | u8 buffer[GHASH_BLOCK_SIZE]; | |
32 | u32 bytes; | |
33 | }; | |
34 | ||
35 | static int ghash_init(struct shash_desc *desc) | |
36 | { | |
37 | struct ghash_desc_ctx *dctx = shash_desc_ctx(desc); | |
38 | ||
39 | memset(dctx, 0, sizeof(*dctx)); | |
40 | ||
41 | return 0; | |
42 | } | |
43 | ||
44 | static int ghash_setkey(struct crypto_shash *tfm, | |
45 | const u8 *key, unsigned int keylen) | |
46 | { | |
47 | struct ghash_ctx *ctx = crypto_shash_ctx(tfm); | |
48 | ||
49 | if (keylen != GHASH_BLOCK_SIZE) { | |
50 | crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN); | |
51 | return -EINVAL; | |
52 | } | |
53 | ||
54 | if (ctx->gf128) | |
55 | gf128mul_free_4k(ctx->gf128); | |
56 | ctx->gf128 = gf128mul_init_4k_lle((be128 *)key); | |
57 | if (!ctx->gf128) | |
58 | return -ENOMEM; | |
59 | ||
60 | return 0; | |
61 | } | |
62 | ||
63 | static int ghash_update(struct shash_desc *desc, | |
64 | const u8 *src, unsigned int srclen) | |
65 | { | |
66 | struct ghash_desc_ctx *dctx = shash_desc_ctx(desc); | |
67 | struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm); | |
68 | u8 *dst = dctx->buffer; | |
69 | ||
70 | if (dctx->bytes) { | |
71 | int n = min(srclen, dctx->bytes); | |
72 | u8 *pos = dst + (GHASH_BLOCK_SIZE - dctx->bytes); | |
73 | ||
74 | dctx->bytes -= n; | |
75 | srclen -= n; | |
76 | ||
77 | while (n--) | |
78 | *pos++ ^= *src++; | |
79 | ||
80 | if (!dctx->bytes) | |
81 | gf128mul_4k_lle((be128 *)dst, ctx->gf128); | |
82 | } | |
83 | ||
84 | while (srclen >= GHASH_BLOCK_SIZE) { | |
85 | crypto_xor(dst, src, GHASH_BLOCK_SIZE); | |
86 | gf128mul_4k_lle((be128 *)dst, ctx->gf128); | |
87 | src += GHASH_BLOCK_SIZE; | |
88 | srclen -= GHASH_BLOCK_SIZE; | |
89 | } | |
90 | ||
91 | if (srclen) { | |
92 | dctx->bytes = GHASH_BLOCK_SIZE - srclen; | |
93 | while (srclen--) | |
94 | *dst++ ^= *src++; | |
95 | } | |
96 | ||
97 | return 0; | |
98 | } | |
99 | ||
100 | static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx) | |
101 | { | |
102 | u8 *dst = dctx->buffer; | |
103 | ||
104 | if (dctx->bytes) { | |
105 | u8 *tmp = dst + (GHASH_BLOCK_SIZE - dctx->bytes); | |
106 | ||
107 | while (dctx->bytes--) | |
108 | *tmp++ ^= 0; | |
109 | ||
110 | gf128mul_4k_lle((be128 *)dst, ctx->gf128); | |
111 | } | |
112 | ||
113 | dctx->bytes = 0; | |
114 | } | |
115 | ||
116 | static int ghash_final(struct shash_desc *desc, u8 *dst) | |
117 | { | |
118 | struct ghash_desc_ctx *dctx = shash_desc_ctx(desc); | |
119 | struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm); | |
120 | u8 *buf = dctx->buffer; | |
121 | ||
122 | ghash_flush(ctx, dctx); | |
123 | memcpy(dst, buf, GHASH_BLOCK_SIZE); | |
124 | ||
125 | return 0; | |
126 | } | |
127 | ||
128 | static void ghash_exit_tfm(struct crypto_tfm *tfm) | |
129 | { | |
130 | struct ghash_ctx *ctx = crypto_tfm_ctx(tfm); | |
131 | if (ctx->gf128) | |
132 | gf128mul_free_4k(ctx->gf128); | |
133 | } | |
134 | ||
135 | static struct shash_alg ghash_alg = { | |
136 | .digestsize = GHASH_DIGEST_SIZE, | |
137 | .init = ghash_init, | |
138 | .update = ghash_update, | |
139 | .final = ghash_final, | |
140 | .setkey = ghash_setkey, | |
141 | .descsize = sizeof(struct ghash_desc_ctx), | |
142 | .base = { | |
143 | .cra_name = "ghash", | |
144 | .cra_driver_name = "ghash-generic", | |
145 | .cra_priority = 100, | |
146 | .cra_flags = CRYPTO_ALG_TYPE_SHASH, | |
147 | .cra_blocksize = GHASH_BLOCK_SIZE, | |
148 | .cra_ctxsize = sizeof(struct ghash_ctx), | |
149 | .cra_module = THIS_MODULE, | |
150 | .cra_list = LIST_HEAD_INIT(ghash_alg.base.cra_list), | |
151 | .cra_exit = ghash_exit_tfm, | |
152 | }, | |
153 | }; | |
154 | ||
155 | static int __init ghash_mod_init(void) | |
156 | { | |
157 | return crypto_register_shash(&ghash_alg); | |
158 | } | |
159 | ||
160 | static void __exit ghash_mod_exit(void) | |
161 | { | |
162 | crypto_unregister_shash(&ghash_alg); | |
163 | } | |
164 | ||
165 | module_init(ghash_mod_init); | |
166 | module_exit(ghash_mod_exit); | |
167 | ||
168 | MODULE_LICENSE("GPL"); | |
169 | MODULE_DESCRIPTION("GHASH Message Digest Algorithm"); | |
170 | MODULE_ALIAS("ghash"); |