text: /*
   * 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 <crypto/internal/hash.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/mm.h>
  #include <linux/cryptohash.h>
  #include <linux/types.h>
  #include <crypto/sha.h>
  #include <asm/byteorder.h>
  
  static int sha1_init(struct shash_desc *desc)
  {
  	struct sha1_state *sctx = shash_desc_ctx(desc);
  
  	*sctx = (struct sha1_state){
  		.state = { SHA1_H0, SHA1_H1, SHA1_H2, SHA1_H3, SHA1_H4 },
  	};
  
  	return 0;
  }
  
  static int sha1_update(struct shash_desc *desc, const u8 *data,
  			unsigned int len)
  {
  	struct sha1_state *sctx = shash_desc_ctx(desc);
  	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);
  
  	return 0;
  }
  
  /* Add padding and return the message digest. */
  static int sha1_final(struct shash_desc *desc, u8 *out)
  {
  	struct sha1_state *sctx = shash_desc_ctx(desc);
  	__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(desc, padding, padlen);
  
  	/* Append length */
  	sha1_update(desc, (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);
  
  	return 0;
  }
  
  static int sha1_export(struct shash_desc *desc, void *out)
  {
  	struct sha1_state *sctx = shash_desc_ctx(desc);
  
  	memcpy(out, sctx, sizeof(*sctx));
  	return 0;
  }
  
  static int sha1_import(struct shash_desc *desc, const void *in)
  {
  	struct sha1_state *sctx = shash_desc_ctx(desc);
  
  	memcpy(sctx, in, sizeof(*sctx));
  	return 0;
  }
  
  static struct shash_alg alg = {
  	.digestsize	=	SHA1_DIGEST_SIZE,
  	.init		=	sha1_init,
  	.update		=	sha1_update,
  	.final		=	sha1_final,
  	.export		=	sha1_export,
  	.import		=	sha1_import,
  	.descsize	=	sizeof(struct sha1_state),
  	.statesize	=	sizeof(struct sha1_state),
  	.base		=	{
  		.cra_name	=	"sha1",
  		.cra_driver_name=	"sha1-generic",
  		.cra_flags	=	CRYPTO_ALG_TYPE_SHASH,
  		.cra_blocksize	=	SHA1_BLOCK_SIZE,
  		.cra_module	=	THIS_MODULE,
  	}
  };
  
  static int __init sha1_generic_mod_init(void)
  {
  	return crypto_register_shash(&alg);
  }
  
  static void __exit sha1_generic_mod_fini(void)
  {
  	crypto_unregister_shash(&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");
  