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Subject[PATCH -v2 1/5] crypto: Add GHASH digest algorithm for GCM
Date
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.

v2:
- Fix a bug in Makefile (Thanks Sebastian)
- Some other minor fixes

Signed-off-by: Huang Ying <ying.huang@intel.com>
---
crypto/Kconfig | 7 ++
crypto/Makefile | 1 +
crypto/ghash-generic.c | 170 ++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 178 insertions(+), 0 deletions(-)
create mode 100644 crypto/ghash-generic.c
diff --git a/crypto/Kconfig b/crypto/Kconfig
index f2002d8..0ae170e 100644
--- 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
--- 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
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");
--
1.6.3.3


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