/*

   * Cryptographic API.
   *
   * Null algorithms, aka Much Ado About Nothing.
   *
   * These are needed for IPsec, and may be useful in general for
   * testing & debugging.

   *

   * The null cipher is compliant with RFC2410.
   *
   * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
   *
   * 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 <crypto/internal/skcipher.h>

  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/mm.h>

  #include <linux/string.h>

  
  #define NULL_KEY_SIZE		0
  #define NULL_BLOCK_SIZE		1
  #define NULL_DIGEST_SIZE	0

  #define NULL_IV_SIZE		0

  static int null_compress(struct crypto_tfm *tfm, const u8 *src,
  			 unsigned int slen, u8 *dst, unsigned int *dlen)

  {
  	if (slen > *dlen)
  		return -EINVAL;
  	memcpy(dst, src, slen);
  	*dlen = slen;
  	return 0;
  }

  static int null_init(struct shash_desc *desc)
  {
  	return 0;
  }

  static int null_update(struct shash_desc *desc, const u8 *data,
  		       unsigned int len)
  {
  	return 0;
  }

  static int null_final(struct shash_desc *desc, u8 *out)
  {
  	return 0;
  }
  
  static int null_digest(struct shash_desc *desc, const u8 *data,
  		       unsigned int len, u8 *out)
  {
  	return 0;
  }
  
  static int null_hash_setkey(struct crypto_shash *tfm, const u8 *key,
  			    unsigned int keylen)
  { return 0; }

  static int null_setkey(struct crypto_tfm *tfm, const u8 *key,

  		       unsigned int keylen)

  { return 0; }

  static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)

  {
  	memcpy(dst, src, NULL_BLOCK_SIZE);
  }

  static int skcipher_null_crypt(struct blkcipher_desc *desc,
  			       struct scatterlist *dst,
  			       struct scatterlist *src, unsigned int nbytes)
  {
  	struct blkcipher_walk walk;
  	int err;
  
  	blkcipher_walk_init(&walk, dst, src, nbytes);
  	err = blkcipher_walk_virt(desc, &walk);
  
  	while (walk.nbytes) {
  		if (walk.src.virt.addr != walk.dst.virt.addr)
  			memcpy(walk.dst.virt.addr, walk.src.virt.addr,
  			       walk.nbytes);
  		err = blkcipher_walk_done(desc, &walk, 0);
  	}
  
  	return err;
  }

  static struct shash_alg digest_null = {
  	.digestsize		=	NULL_DIGEST_SIZE,
  	.setkey   		=	null_hash_setkey,
  	.init   		=	null_init,
  	.update 		=	null_update,
  	.finup 			=	null_digest,
  	.digest 		=	null_digest,
  	.final  		=	null_final,
  	.base			=	{
  		.cra_name		=	"digest_null",
  		.cra_flags		=	CRYPTO_ALG_TYPE_SHASH,
  		.cra_blocksize		=	NULL_BLOCK_SIZE,
  		.cra_module		=	THIS_MODULE,
  	}

  };

  static struct crypto_alg null_algs[3] = { {

  	.cra_name		=	"cipher_null",
  	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
  	.cra_blocksize		=	NULL_BLOCK_SIZE,
  	.cra_ctxsize		=	0,
  	.cra_module		=	THIS_MODULE,

  	.cra_u			=	{ .cipher = {
  	.cia_min_keysize	=	NULL_KEY_SIZE,
  	.cia_max_keysize	=	NULL_KEY_SIZE,
  	.cia_setkey		= 	null_setkey,

  	.cia_encrypt		=	null_crypt,
  	.cia_decrypt		=	null_crypt } }

  }, {

  	.cra_name		=	"ecb(cipher_null)",
  	.cra_driver_name	=	"ecb-cipher_null",
  	.cra_priority		=	100,
  	.cra_flags		=	CRYPTO_ALG_TYPE_BLKCIPHER,
  	.cra_blocksize		=	NULL_BLOCK_SIZE,
  	.cra_type		=	&crypto_blkcipher_type,
  	.cra_ctxsize		=	0,
  	.cra_module		=	THIS_MODULE,

  	.cra_u			=	{ .blkcipher = {
  	.min_keysize		=	NULL_KEY_SIZE,
  	.max_keysize		=	NULL_KEY_SIZE,
  	.ivsize			=	NULL_IV_SIZE,
  	.setkey			= 	null_setkey,
  	.encrypt		=	skcipher_null_crypt,
  	.decrypt		=	skcipher_null_crypt } }

  }, {
  	.cra_name		=	"compress_null",
  	.cra_flags		=	CRYPTO_ALG_TYPE_COMPRESS,
  	.cra_blocksize		=	NULL_BLOCK_SIZE,
  	.cra_ctxsize		=	0,
  	.cra_module		=	THIS_MODULE,
  	.cra_u			=	{ .compress = {
  	.coa_compress		=	null_compress,
  	.coa_decompress		=	null_compress } }
  } };

  MODULE_ALIAS("compress_null");
  MODULE_ALIAS("digest_null");
  MODULE_ALIAS("cipher_null");

  static int __init crypto_null_mod_init(void)

  {
  	int ret = 0;

  	ret = crypto_register_algs(null_algs, ARRAY_SIZE(null_algs));

  	if (ret < 0)
  		goto out;

  	ret = crypto_register_shash(&digest_null);

  	if (ret < 0)

  		goto out_unregister_algs;

  	return 0;

  out_unregister_algs:
  	crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));

  out:

  	return ret;
  }

  static void __exit crypto_null_mod_fini(void)

  {

  	crypto_unregister_shash(&digest_null);

  	crypto_unregister_algs(null_algs, ARRAY_SIZE(null_algs));

  }

  module_init(crypto_null_mod_init);
  module_exit(crypto_null_mod_fini);

  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("Null Cryptographic Algorithms");