LXR RHEL4/crypto/crc32c.c

   1/* 
   2 * Cryptographic API.
   3 *
   4 * CRC32C chksum
   5 *
   6 * This module file is a wrapper to invoke the lib/crc32c routines.
   7 *
   8 * This program is free software; you can redistribute it and/or modify it
   9 * under the terms of the GNU General Public License as published by the Free
  10 * Software Foundation; either version 2 of the License, or (at your option) 
  11 * any later version.
  12 *
  13 */
  14#include <linux/init.h>
  15#include <linux/module.h>
  16#include <linux/string.h>
  17#include <linux/crypto.h>
  18#include <linux/crc32c.h>
  19#include <asm/byteorder.h>
  20
  21#define CHKSUM_BLOCK_SIZE       32
  22#define CHKSUM_DIGEST_SIZE      4
  23
  24struct chksum_ctx {
  25        u32 crc;
  26};
  27
  28/*
  29 * Steps through buffer one byte at at time, calculates reflected 
  30 * crc using table.
  31 */
  32
  33static void chksum_init(void *ctx)
  34{
  35        struct chksum_ctx *mctx = ctx;
  36
  37        mctx->crc = ~(u32)0;                    /* common usage */
  38}
  39
  40/*
  41 * Setting the seed allows arbitrary accumulators and flexible XOR policy
  42 * If your algorithm starts with ~0, then XOR with ~0 before you set
  43 * the seed.
  44 */
  45static int chksum_setkey(void *ctx, const u8 *key, unsigned int keylen,
  46                          u32 *flags)
  47{
  48        struct chksum_ctx *mctx = ctx;
  49
  50        if (keylen != sizeof(mctx->crc)) {
  51                if (flags)
  52                        *flags = CRYPTO_TFM_RES_BAD_KEY_LEN;
  53                return -EINVAL;
  54        }
  55        mctx->crc = __cpu_to_le32(*(u32 *)key);
  56        return 0;
  57}
  58
  59static void chksum_update(void *ctx, const u8 *data, unsigned int length)
  60{
  61        struct chksum_ctx *mctx = ctx;
  62        u32 mcrc;
  63
  64        mcrc = crc32c(mctx->crc, data, (size_t)length);
  65
  66        mctx->crc = mcrc;
  67}
  68
  69static void chksum_final(void *ctx, u8 *out)
  70{
  71        struct chksum_ctx *mctx = ctx;
  72        u32 mcrc = (mctx->crc ^ ~(u32)0);
  73        
  74        *(u32 *)out = __le32_to_cpu(mcrc);
  75}
  76
  77static struct crypto_alg alg = {
  78        .cra_name       =       "crc32c",
  79        .cra_flags      =       CRYPTO_ALG_TYPE_DIGEST,
  80        .cra_blocksize  =       CHKSUM_BLOCK_SIZE,
  81        .cra_ctxsize    =       sizeof(struct chksum_ctx),
  82        .cra_module     =       THIS_MODULE,
  83        .cra_list       =       LIST_HEAD_INIT(alg.cra_list),
  84        .cra_u          =       {
  85                .digest = {
  86                         .dia_digestsize=       CHKSUM_DIGEST_SIZE,
  87                         .dia_setkey    =       chksum_setkey,
  88                         .dia_init      =       chksum_init,
  89                         .dia_update    =       chksum_update,
  90                         .dia_final     =       chksum_final
  91                 }
  92        }
  93};
  94
  95static int __init init(void)
  96{
  97        return crypto_register_alg(&alg);
  98}
  99
 100static void __exit fini(void)
 101{
 102        crypto_unregister_alg(&alg);
 103}
 104
 105module_init(init);
 106module_exit(fini);
 107
 108MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
 109MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c");
 110MODULE_LICENSE("GPL");
 111