blob: be4425616931ffcf0f1747aa752d76f15379c989 [file] [log] [blame]
Huang Ying2cdc6892009-08-06 15:32:38 +10001/*
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
26struct ghash_ctx {
27 struct gf128mul_4k *gf128;
28};
29
30struct ghash_desc_ctx {
31 u8 buffer[GHASH_BLOCK_SIZE];
32 u32 bytes;
33};
34
35static 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
44static 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
63static 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
100static 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
116static 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
128static 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
135static 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
155static int __init ghash_mod_init(void)
156{
157 return crypto_register_shash(&ghash_alg);
158}
159
160static void __exit ghash_mod_exit(void)
161{
162 crypto_unregister_shash(&ghash_alg);
163}
164
165module_init(ghash_mod_init);
166module_exit(ghash_mod_exit);
167
168MODULE_LICENSE("GPL");
169MODULE_DESCRIPTION("GHASH Message Digest Algorithm");
170MODULE_ALIAS("ghash");