/*
   * 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 sha1_generic_mod_init(void)

  {
  	return crypto_register_alg(&alg);
  }

  static void __exit sha1_generic_mod_fini(void)

  {
  	crypto_unregister_alg(&alg);
  }

  module_init(sha1_generic_mod_init);
  module_exit(sha1_generic_mod_fini);

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

  MODULE_ALIAS("sha1");