/* 
   * 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 <linux/init.h>
  #include <linux/module.h>
  #include <linux/mm.h>
  #include <asm/scatterlist.h>
  #include <linux/crypto.h>

  #include <linux/string.h>

  
  #define NULL_KEY_SIZE		0
  #define NULL_BLOCK_SIZE		1
  #define NULL_DIGEST_SIZE	0
  
  static int null_compress(void *ctx, 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 void null_init(void *ctx)
  { }
  
  static void null_update(void *ctx, const u8 *data, unsigned int len)
  { }
  
  static void null_final(void *ctx, u8 *out)
  { }
  
  static int null_setkey(void *ctx, const u8 *key,
                         unsigned int keylen, u32 *flags)
  { return 0; }

  static void null_crypt(void *ctx, u8 *dst, const u8 *src)
  {
  	memcpy(dst, src, NULL_BLOCK_SIZE);
  }

  
  static struct crypto_alg compress_null = {
  	.cra_name		=	"compress_null",
  	.cra_flags		=	CRYPTO_ALG_TYPE_COMPRESS,
  	.cra_blocksize		=	NULL_BLOCK_SIZE,
  	.cra_ctxsize		=	0,
  	.cra_module		=	THIS_MODULE,
  	.cra_list		=       LIST_HEAD_INIT(compress_null.cra_list),
  	.cra_u			=	{ .compress = {
  	.coa_compress 		=	null_compress,

  	.coa_decompress		=	null_compress } }

  };
  
  static struct crypto_alg digest_null = {
  	.cra_name		=	"digest_null",
  	.cra_flags		=	CRYPTO_ALG_TYPE_DIGEST,
  	.cra_blocksize		=	NULL_BLOCK_SIZE,
  	.cra_ctxsize		=	0,
  	.cra_module		=	THIS_MODULE,
  	.cra_list		=       LIST_HEAD_INIT(digest_null.cra_list),	
  	.cra_u			=	{ .digest = {
  	.dia_digestsize		=	NULL_DIGEST_SIZE,
  	.dia_init   		=	null_init,
  	.dia_update 		=	null_update,
  	.dia_final  		=	null_final } }
  };
  
  static struct crypto_alg cipher_null = {
  	.cra_name		=	"cipher_null",
  	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
  	.cra_blocksize		=	NULL_BLOCK_SIZE,
  	.cra_ctxsize		=	0,
  	.cra_module		=	THIS_MODULE,
  	.cra_list		=	LIST_HEAD_INIT(cipher_null.cra_list),
  	.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 } }

  };
  
  MODULE_ALIAS("compress_null");
  MODULE_ALIAS("digest_null");
  MODULE_ALIAS("cipher_null");
  
  static int __init init(void)
  {
  	int ret = 0;
  	
  	ret = crypto_register_alg(&cipher_null);
  	if (ret < 0)
  		goto out;
  
  	ret = crypto_register_alg(&digest_null);
  	if (ret < 0) {
  		crypto_unregister_alg(&cipher_null);
  		goto out;
  	}
  
  	ret = crypto_register_alg(&compress_null);
  	if (ret < 0) {
  		crypto_unregister_alg(&digest_null);
  		crypto_unregister_alg(&cipher_null);
  		goto out;
  	}
  
  out:	
  	return ret;
  }
  
  static void __exit fini(void)
  {
  	crypto_unregister_alg(&compress_null);
  	crypto_unregister_alg(&digest_null);
  	crypto_unregister_alg(&cipher_null);
  }
  
  module_init(init);
  module_exit(fini);
  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("Null Cryptographic Algorithms");