crypto: ghash - Add GHASH digest algorithm for GCM

GHASH is implemented as a shash algorithm. The actual implementation
is copied from gcm.c. This makes it possible to add
architecture/hardware accelerated GHASH implementation.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/Kconfig b/crypto/Kconfig
index f2002d8..0ae170e 100644 (file)
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -290,6 +290,13 @@ config CRYPTO_CRC32C_INTEL
          gain performance compared with software implementation.
          Module will be crc32c-intel.
 
+config CRYPTO_GHASH
+       tristate "GHASH digest algorithm"
+       select CRYPTO_SHASH
+       select CRYPTO_GF128MUL
+       help
+         GHASH is message digest algorithm for GCM (Galois/Counter Mode).
+
 config CRYPTO_MD4
        tristate "MD4 digest algorithm"
        select CRYPTO_HASH

diff --git a/crypto/Makefile b/crypto/Makefile
index 3c961b4..c2ca721 100644 (file)
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -82,6 +82,7 @@ obj-$(CONFIG_CRYPTO_RNG2) += rng.o
 obj-$(CONFIG_CRYPTO_RNG2) += krng.o
 obj-$(CONFIG_CRYPTO_ANSI_CPRNG) += ansi_cprng.o
 obj-$(CONFIG_CRYPTO_TEST) += tcrypt.o
+obj-$(CONFIG_CRYPTO_GHASH) += ghash-generic.o
 
 #
 # generic algorithms and the async_tx api

diff --git a/crypto/ghash-generic.c b/crypto/ghash-generic.c
new file mode 100644 (file)
index 0000000..be44256
--- /dev/null
+++ b/crypto/ghash-generic.c
@@ -0,0 +1,170 @@
+/*
+ * GHASH: digest algorithm for GCM (Galois/Counter Mode).
+ *
+ * Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <mh1@iki.fi>
+ * Copyright (c) 2009 Intel Corp.
+ *   Author: Huang Ying <ying.huang@intel.com>
+ *
+ * The algorithm implementation is copied from gcm.c.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <crypto/algapi.h>
+#include <crypto/gf128mul.h>
+#include <crypto/internal/hash.h>
+#include <linux/crypto.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#define GHASH_BLOCK_SIZE       16
+#define GHASH_DIGEST_SIZE      16
+
+struct ghash_ctx {
+       struct gf128mul_4k *gf128;
+};
+
+struct ghash_desc_ctx {
+       u8 buffer[GHASH_BLOCK_SIZE];
+       u32 bytes;
+};
+
+static int ghash_init(struct shash_desc *desc)
+{
+       struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
+
+       memset(dctx, 0, sizeof(*dctx));
+
+       return 0;
+}
+
+static int ghash_setkey(struct crypto_shash *tfm,
+                       const u8 *key, unsigned int keylen)
+{
+       struct ghash_ctx *ctx = crypto_shash_ctx(tfm);
+
+       if (keylen != GHASH_BLOCK_SIZE) {
+               crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
+               return -EINVAL;
+       }
+
+       if (ctx->gf128)
+               gf128mul_free_4k(ctx->gf128);
+       ctx->gf128 = gf128mul_init_4k_lle((be128 *)key);
+       if (!ctx->gf128)
+               return -ENOMEM;
+
+       return 0;
+}
+
+static int ghash_update(struct shash_desc *desc,
+                        const u8 *src, unsigned int srclen)
+{
+       struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
+       struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
+       u8 *dst = dctx->buffer;
+
+       if (dctx->bytes) {
+               int n = min(srclen, dctx->bytes);
+               u8 *pos = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
+
+               dctx->bytes -= n;
+               srclen -= n;
+
+               while (n--)
+                       *pos++ ^= *src++;
+
+               if (!dctx->bytes)
+                       gf128mul_4k_lle((be128 *)dst, ctx->gf128);
+       }
+
+       while (srclen >= GHASH_BLOCK_SIZE) {
+               crypto_xor(dst, src, GHASH_BLOCK_SIZE);
+               gf128mul_4k_lle((be128 *)dst, ctx->gf128);
+               src += GHASH_BLOCK_SIZE;
+               srclen -= GHASH_BLOCK_SIZE;
+       }
+
+       if (srclen) {
+               dctx->bytes = GHASH_BLOCK_SIZE - srclen;
+               while (srclen--)
+                       *dst++ ^= *src++;
+       }
+
+       return 0;
+}
+
+static void ghash_flush(struct ghash_ctx *ctx, struct ghash_desc_ctx *dctx)
+{
+       u8 *dst = dctx->buffer;
+
+       if (dctx->bytes) {
+               u8 *tmp = dst + (GHASH_BLOCK_SIZE - dctx->bytes);
+
+               while (dctx->bytes--)
+                       *tmp++ ^= 0;
+
+               gf128mul_4k_lle((be128 *)dst, ctx->gf128);
+       }
+
+       dctx->bytes = 0;
+}
+
+static int ghash_final(struct shash_desc *desc, u8 *dst)
+{
+       struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);
+       struct ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
+       u8 *buf = dctx->buffer;
+
+       ghash_flush(ctx, dctx);
+       memcpy(dst, buf, GHASH_BLOCK_SIZE);
+
+       return 0;
+}
+
+static void ghash_exit_tfm(struct crypto_tfm *tfm)
+{
+       struct ghash_ctx *ctx = crypto_tfm_ctx(tfm);
+       if (ctx->gf128)
+               gf128mul_free_4k(ctx->gf128);
+}
+
+static struct shash_alg ghash_alg = {
+       .digestsize     = GHASH_DIGEST_SIZE,
+       .init           = ghash_init,
+       .update         = ghash_update,
+       .final          = ghash_final,
+       .setkey         = ghash_setkey,
+       .descsize       = sizeof(struct ghash_desc_ctx),
+       .base           = {
+               .cra_name               = "ghash",
+               .cra_driver_name        = "ghash-generic",
+               .cra_priority           = 100,
+               .cra_flags              = CRYPTO_ALG_TYPE_SHASH,
+               .cra_blocksize          = GHASH_BLOCK_SIZE,
+               .cra_ctxsize            = sizeof(struct ghash_ctx),
+               .cra_module             = THIS_MODULE,
+               .cra_list               = LIST_HEAD_INIT(ghash_alg.base.cra_list),
+               .cra_exit               = ghash_exit_tfm,
+       },
+};
+
+static int __init ghash_mod_init(void)
+{
+       return crypto_register_shash(&ghash_alg);
+}
+
+static void __exit ghash_mod_exit(void)
+{
+       crypto_unregister_shash(&ghash_alg);
+}
+
+module_init(ghash_mod_init);
+module_exit(ghash_mod_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("GHASH Message Digest Algorithm");
+MODULE_ALIAS("ghash");