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sha1_generic.c

/*
 * Cryptographic API.
 *
 * SHA1 Secure Hash Algorithm.
 *
 * Derived from cryptoapi implementation, adapted for in-place
 * scatterlist interface.
 *
 * Copyright (c) Alan Smithee.
 * Copyright (c) Andrew McDonald <andrew@mcdonald.org.uk>
 * Copyright (c) Jean-Francois Dive <jef@linuxbe.org>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 */
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/crypto.h>
#include <linux/cryptohash.h>
#include <linux/types.h>
#include <crypto/sha.h>
#include <asm/byteorder.h>

struct sha1_ctx {
        u64 count;
        u32 state[5];
        u8 buffer[64];
};

static void sha1_init(struct crypto_tfm *tfm)
{
      struct sha1_ctx *sctx = crypto_tfm_ctx(tfm);
      static const struct sha1_ctx initstate = {
        0,
        { SHA1_H0, SHA1_H1, SHA1_H2, SHA1_H3, SHA1_H4 },
        { 0, }
      };

      *sctx = initstate;
}

static void sha1_update(struct crypto_tfm *tfm, const u8 *data,
                  unsigned int len)
{
      struct sha1_ctx *sctx = crypto_tfm_ctx(tfm);
      unsigned int partial, done;
      const u8 *src;

      partial = sctx->count & 0x3f;
      sctx->count += len;
      done = 0;
      src = data;

      if ((partial + len) > 63) {
            u32 temp[SHA_WORKSPACE_WORDS];

            if (partial) {
                  done = -partial;
                  memcpy(sctx->buffer + partial, data, done + 64);
                  src = sctx->buffer;
            }

            do {
                  sha_transform(sctx->state, src, temp);
                  done += 64;
                  src = data + done;
            } while (done + 63 < len);

            memset(temp, 0, sizeof(temp));
            partial = 0;
      }
      memcpy(sctx->buffer + partial, src, len - done);
}


/* Add padding and return the message digest. */
static void sha1_final(struct crypto_tfm *tfm, u8 *out)
{
      struct sha1_ctx *sctx = crypto_tfm_ctx(tfm);
      __be32 *dst = (__be32 *)out;
      u32 i, index, padlen;
      __be64 bits;
      static const u8 padding[64] = { 0x80, };

      bits = cpu_to_be64(sctx->count << 3);

      /* Pad out to 56 mod 64 */
      index = sctx->count & 0x3f;
      padlen = (index < 56) ? (56 - index) : ((64+56) - index);
      sha1_update(tfm, padding, padlen);

      /* Append length */
      sha1_update(tfm, (const u8 *)&bits, sizeof(bits));

      /* Store state in digest */
      for (i = 0; i < 5; i++)
            dst[i] = cpu_to_be32(sctx->state[i]);

      /* Wipe context */
      memset(sctx, 0, sizeof *sctx);
}

static struct crypto_alg alg = {
      .cra_name   =     "sha1",
      .cra_driver_name= "sha1-generic",
      .cra_flags  =     CRYPTO_ALG_TYPE_DIGEST,
      .cra_blocksize    =     SHA1_BLOCK_SIZE,
      .cra_ctxsize      =     sizeof(struct sha1_ctx),
      .cra_module =     THIS_MODULE,
      .cra_alignmask    =     3,
      .cra_list       =       LIST_HEAD_INIT(alg.cra_list),
      .cra_u            =     { .digest = {
      .dia_digestsize   =     SHA1_DIGEST_SIZE,
      .dia_init         =     sha1_init,
      .dia_update       =     sha1_update,
      .dia_final        =     sha1_final } }
};

static int __init init(void)
{
      return crypto_register_alg(&alg);
}

static void __exit fini(void)
{
      crypto_unregister_alg(&alg);
}

module_init(init);
module_exit(fini);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("SHA1 Secure Hash Algorithm");

MODULE_ALIAS("sha1");

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