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crypto_null.c

/* 
 * 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 <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(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 void null_init(struct crypto_tfm *tfm)
{ }

static void null_update(struct crypto_tfm *tfm, const u8 *data,
                  unsigned int len)
{ }

static void null_final(struct crypto_tfm *tfm, u8 *out)
{ }

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 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");

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