linux/crypto/crypto_null.c
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   1/* 
   2 * Cryptographic API.
   3 *
   4 * Null algorithms, aka Much Ado About Nothing.
   5 *
   6 * These are needed for IPsec, and may be useful in general for
   7 * testing & debugging.
   8 * 
   9 * The null cipher is compliant with RFC2410.
  10 *
  11 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
  12 *
  13 * This program is free software; you can redistribute it and/or modify
  14 * it under the terms of the GNU General Public License as published by
  15 * the Free Software Foundation; either version 2 of the License, or
  16 * (at your option) any later version.
  17 *
  18 */
  19#include <linux/init.h>
  20#include <linux/module.h>
  21#include <linux/mm.h>
  22#include <asm/scatterlist.h>
  23#include <linux/crypto.h>
  24#include <linux/string.h>
  25
  26#define NULL_KEY_SIZE           0
  27#define NULL_BLOCK_SIZE         1
  28#define NULL_DIGEST_SIZE        0
  29
  30static int null_compress(struct crypto_tfm *tfm, const u8 *src,
  31                         unsigned int slen, u8 *dst, unsigned int *dlen)
  32{
  33        if (slen > *dlen)
  34                return -EINVAL;
  35        memcpy(dst, src, slen);
  36        *dlen = slen;
  37        return 0;
  38}
  39
  40static void null_init(struct crypto_tfm *tfm)
  41{ }
  42
  43static void null_update(struct crypto_tfm *tfm, const u8 *data,
  44                        unsigned int len)
  45{ }
  46
  47static void null_final(struct crypto_tfm *tfm, u8 *out)
  48{ }
  49
  50static int null_setkey(struct crypto_tfm *tfm, const u8 *key,
  51                       unsigned int keylen)
  52{ return 0; }
  53
  54static void null_crypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
  55{
  56        memcpy(dst, src, NULL_BLOCK_SIZE);
  57}
  58
  59static struct crypto_alg compress_null = {
  60        .cra_name               =       "compress_null",
  61        .cra_flags              =       CRYPTO_ALG_TYPE_COMPRESS,
  62        .cra_blocksize          =       NULL_BLOCK_SIZE,
  63        .cra_ctxsize            =       0,
  64        .cra_module             =       THIS_MODULE,
  65        .cra_list               =       LIST_HEAD_INIT(compress_null.cra_list),
  66        .cra_u                  =       { .compress = {
  67        .coa_compress           =       null_compress,
  68        .coa_decompress         =       null_compress } }
  69};
  70
  71static struct crypto_alg digest_null = {
  72        .cra_name               =       "digest_null",
  73        .cra_flags              =       CRYPTO_ALG_TYPE_DIGEST,
  74        .cra_blocksize          =       NULL_BLOCK_SIZE,
  75        .cra_ctxsize            =       0,
  76        .cra_module             =       THIS_MODULE,
  77        .cra_list               =       LIST_HEAD_INIT(digest_null.cra_list),   
  78        .cra_u                  =       { .digest = {
  79        .dia_digestsize         =       NULL_DIGEST_SIZE,
  80        .dia_init               =       null_init,
  81        .dia_update             =       null_update,
  82        .dia_final              =       null_final } }
  83};
  84
  85static struct crypto_alg cipher_null = {
  86        .cra_name               =       "cipher_null",
  87        .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,
  88        .cra_blocksize          =       NULL_BLOCK_SIZE,
  89        .cra_ctxsize            =       0,
  90        .cra_module             =       THIS_MODULE,
  91        .cra_list               =       LIST_HEAD_INIT(cipher_null.cra_list),
  92        .cra_u                  =       { .cipher = {
  93        .cia_min_keysize        =       NULL_KEY_SIZE,
  94        .cia_max_keysize        =       NULL_KEY_SIZE,
  95        .cia_setkey             =       null_setkey,
  96        .cia_encrypt            =       null_crypt,
  97        .cia_decrypt            =       null_crypt } }
  98};
  99
 100MODULE_ALIAS("compress_null");
 101MODULE_ALIAS("digest_null");
 102MODULE_ALIAS("cipher_null");
 103
 104static int __init init(void)
 105{
 106        int ret = 0;
 107        
 108        ret = crypto_register_alg(&cipher_null);
 109        if (ret < 0)
 110                goto out;
 111
 112        ret = crypto_register_alg(&digest_null);
 113        if (ret < 0) {
 114                crypto_unregister_alg(&cipher_null);
 115                goto out;
 116        }
 117
 118        ret = crypto_register_alg(&compress_null);
 119        if (ret < 0) {
 120                crypto_unregister_alg(&digest_null);
 121                crypto_unregister_alg(&cipher_null);
 122                goto out;
 123        }
 124
 125out:    
 126        return ret;
 127}
 128
 129static void __exit fini(void)
 130{
 131        crypto_unregister_alg(&compress_null);
 132        crypto_unregister_alg(&digest_null);
 133        crypto_unregister_alg(&cipher_null);
 134}
 135
 136module_init(init);
 137module_exit(fini);
 138
 139MODULE_LICENSE("GPL");
 140MODULE_DESCRIPTION("Null Cryptographic Algorithms");
 141
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