1 // SPDX-License-Identifier: GPL-2.0-only
3 * GHASH: digest algorithm for GCM (Galois/Counter Mode).
5 * Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <mh1@iki.fi>
6 * Copyright (c) 2009 Intel Corp.
7 * Author: Huang Ying <ying.huang@intel.com>
9 * The algorithm implementation is copied from gcm.c.
12 #include <crypto/algapi.h>
13 #include <crypto/gf128mul.h>
14 #include <crypto/ghash.h>
15 #include <crypto/internal/hash.h>
16 #include <linux/crypto.h>
17 #include <linux/init.h>
18 #include <linux/kernel.h>
19 #include <linux/module.h>
21 static int ghash_init(struct shash_desc *desc)
23 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
25 memset(dctx, 0, sizeof(*dctx));
30 static int ghash_setkey(struct crypto_shash *tfm,
31 const u8 *key, unsigned int keylen)
33 struct ghash_ctx *ctx = crypto_shash_ctx(tfm);
36 if (keylen != GHASH_BLOCK_SIZE) {
37 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
42 gf128mul_free_4k(ctx->gf128);
44 BUILD_BUG_ON(sizeof(k) != GHASH_BLOCK_SIZE);
45 memcpy(&k, key, GHASH_BLOCK_SIZE); /* avoid violating alignment rules */
46 ctx->gf128 = gf128mul_init_4k_lle(&k);
47 memzero_explicit(&k, GHASH_BLOCK_SIZE);
55 static int ghash_update(struct shash_desc *desc,
56 const u8 *src, unsigned int srclen)
58 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
59 struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
60 u8 *dst = dctx->buffer;
63 int n = min(srclen, dctx->bytes);
64 u8 *pos = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
73 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
76 while (srclen >= GHASH_BLOCK_SIZE) {
77 crypto_xor(dst, src, GHASH_BLOCK_SIZE);
78 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
79 src += GHASH_BLOCK_SIZE;
80 srclen -= GHASH_BLOCK_SIZE;
84 dctx->bytes = GHASH_BLOCK_SIZE - srclen;
92 static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx)
94 u8 *dst = dctx->buffer;
97 u8 *tmp = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
102 gf128mul_4k_lle((be128 *)dst, ctx->gf128);
108 static int ghash_final(struct shash_desc *desc, u8 *dst)
110 struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
111 struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
112 u8 *buf = dctx->buffer;
114 ghash_flush(ctx, dctx);
115 memcpy(dst, buf, GHASH_BLOCK_SIZE);
120 static void ghash_exit_tfm(struct crypto_tfm *tfm)
122 struct ghash_ctx *ctx = crypto_tfm_ctx(tfm);
124 gf128mul_free_4k(ctx->gf128);
127 static struct shash_alg ghash_alg = {
128 .digestsize = GHASH_DIGEST_SIZE,
130 .update = ghash_update,
131 .final = ghash_final,
132 .setkey = ghash_setkey,
133 .descsize = sizeof(struct ghash_desc_ctx),
136 .cra_driver_name = "ghash-generic",
138 .cra_blocksize = GHASH_BLOCK_SIZE,
139 .cra_ctxsize = sizeof(struct ghash_ctx),
140 .cra_module = THIS_MODULE,
141 .cra_exit = ghash_exit_tfm,
145 static int __init ghash_mod_init(void)
147 return crypto_register_shash(&ghash_alg);
150 static void __exit ghash_mod_exit(void)
152 crypto_unregister_shash(&ghash_alg);
155 subsys_initcall(ghash_mod_init);
156 module_exit(ghash_mod_exit);
158 MODULE_LICENSE("GPL");
159 MODULE_DESCRIPTION("GHASH Message Digest Algorithm");
160 MODULE_ALIAS_CRYPTO("ghash");
161 MODULE_ALIAS_CRYPTO("ghash-generic");