root/crypto/crypto_null.c

DEFINITIONS

1. null_compress
2. null_init
3. null_update
4. null_final
5. null_setkey
6. null_crypt
7. skcipher_null_crypt
8. crypto_null_mod_init
9. crypto_null_mod_fini

/* 
 * 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/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 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 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 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_setkey             =       null_setkey,
        .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 } }
};

static struct crypto_alg skcipher_null = {
        .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_list               =       LIST_HEAD_INIT(skcipher_null.cra_list),
        .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 } }
};

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_alg(&cipher_null);
        if (ret < 0)
                goto out;

        ret = crypto_register_alg(&skcipher_null);
        if (ret < 0)
                goto out_unregister_cipher;

        ret = crypto_register_alg(&digest_null);
        if (ret < 0)
                goto out_unregister_skcipher;

        ret = crypto_register_alg(&compress_null);
        if (ret < 0)
                goto out_unregister_digest;

out:    
        return ret;

out_unregister_digest:
        crypto_unregister_alg(&digest_null);
out_unregister_skcipher:
        crypto_unregister_alg(&skcipher_null);
out_unregister_cipher:
        crypto_unregister_alg(&cipher_null);
        goto out;
}

static void __exit crypto_null_mod_fini(void)
{
        crypto_unregister_alg(&compress_null);
        crypto_unregister_alg(&digest_null);
        crypto_unregister_alg(&skcipher_null);
        crypto_unregister_alg(&cipher_null);
}

module_init(crypto_null_mod_init);
module_exit(crypto_null_mod_fini);

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