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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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