linux/crypto/md5.c
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   1/* 
   2 * Cryptographic API.
   3 *
   4 * MD5 Message Digest Algorithm (RFC1321).
   5 *
   6 * Derived from cryptoapi implementation, originally based on the
   7 * public domain implementation written by Colin Plumb in 1993.
   8 *
   9 * Copyright (c) Cryptoapi developers.
  10 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
  11 * 
  12 * This program is free software; you can redistribute it and/or modify it
  13 * under the terms of the GNU General Public License as published by the Free
  14 * Software Foundation; either version 2 of the License, or (at your option) 
  15 * any later version.
  16 *
  17 */
  18#include <crypto/internal/hash.h>
  19#include <crypto/md5.h>
  20#include <linux/init.h>
  21#include <linux/module.h>
  22#include <linux/string.h>
  23#include <linux/types.h>
  24#include <linux/cryptohash.h>
  25#include <asm/byteorder.h>
  26
  27/* XXX: this stuff can be optimized */
  28static inline void le32_to_cpu_array(u32 *buf, unsigned int words)
  29{
  30        while (words--) {
  31                __le32_to_cpus(buf);
  32                buf++;
  33        }
  34}
  35
  36static inline void cpu_to_le32_array(u32 *buf, unsigned int words)
  37{
  38        while (words--) {
  39                __cpu_to_le32s(buf);
  40                buf++;
  41        }
  42}
  43
  44static inline void md5_transform_helper(struct md5_state *ctx)
  45{
  46        le32_to_cpu_array(ctx->block, sizeof(ctx->block) / sizeof(u32));
  47        md5_transform(ctx->hash, ctx->block);
  48}
  49
  50static int md5_init(struct shash_desc *desc)
  51{
  52        struct md5_state *mctx = shash_desc_ctx(desc);
  53
  54        mctx->hash[0] = 0x67452301;
  55        mctx->hash[1] = 0xefcdab89;
  56        mctx->hash[2] = 0x98badcfe;
  57        mctx->hash[3] = 0x10325476;
  58        mctx->byte_count = 0;
  59
  60        return 0;
  61}
  62
  63static int md5_update(struct shash_desc *desc, const u8 *data, unsigned int len)
  64{
  65        struct md5_state *mctx = shash_desc_ctx(desc);
  66        const u32 avail = sizeof(mctx->block) - (mctx->byte_count & 0x3f);
  67
  68        mctx->byte_count += len;
  69
  70        if (avail > len) {
  71                memcpy((char *)mctx->block + (sizeof(mctx->block) - avail),
  72                       data, len);
  73                return 0;
  74        }
  75
  76        memcpy((char *)mctx->block + (sizeof(mctx->block) - avail),
  77               data, avail);
  78
  79        md5_transform_helper(mctx);
  80        data += avail;
  81        len -= avail;
  82
  83        while (len >= sizeof(mctx->block)) {
  84                memcpy(mctx->block, data, sizeof(mctx->block));
  85                md5_transform_helper(mctx);
  86                data += sizeof(mctx->block);
  87                len -= sizeof(mctx->block);
  88        }
  89
  90        memcpy(mctx->block, data, len);
  91
  92        return 0;
  93}
  94
  95static int md5_final(struct shash_desc *desc, u8 *out)
  96{
  97        struct md5_state *mctx = shash_desc_ctx(desc);
  98        const unsigned int offset = mctx->byte_count & 0x3f;
  99        char *p = (char *)mctx->block + offset;
 100        int padding = 56 - (offset + 1);
 101
 102        *p++ = 0x80;
 103        if (padding < 0) {
 104                memset(p, 0x00, padding + sizeof (u64));
 105                md5_transform_helper(mctx);
 106                p = (char *)mctx->block;
 107                padding = 56;
 108        }
 109
 110        memset(p, 0, padding);
 111        mctx->block[14] = mctx->byte_count << 3;
 112        mctx->block[15] = mctx->byte_count >> 29;
 113        le32_to_cpu_array(mctx->block, (sizeof(mctx->block) -
 114                          sizeof(u64)) / sizeof(u32));
 115        md5_transform(mctx->hash, mctx->block);
 116        cpu_to_le32_array(mctx->hash, sizeof(mctx->hash) / sizeof(u32));
 117        memcpy(out, mctx->hash, sizeof(mctx->hash));
 118        memset(mctx, 0, sizeof(*mctx));
 119
 120        return 0;
 121}
 122
 123static int md5_export(struct shash_desc *desc, void *out)
 124{
 125        struct md5_state *ctx = shash_desc_ctx(desc);
 126
 127        memcpy(out, ctx, sizeof(*ctx));
 128        return 0;
 129}
 130
 131static int md5_import(struct shash_desc *desc, const void *in)
 132{
 133        struct md5_state *ctx = shash_desc_ctx(desc);
 134
 135        memcpy(ctx, in, sizeof(*ctx));
 136        return 0;
 137}
 138
 139static struct shash_alg alg = {
 140        .digestsize     =       MD5_DIGEST_SIZE,
 141        .init           =       md5_init,
 142        .update         =       md5_update,
 143        .final          =       md5_final,
 144        .export         =       md5_export,
 145        .import         =       md5_import,
 146        .descsize       =       sizeof(struct md5_state),
 147        .statesize      =       sizeof(struct md5_state),
 148        .base           =       {
 149                .cra_name       =       "md5",
 150                .cra_flags      =       CRYPTO_ALG_TYPE_SHASH,
 151                .cra_blocksize  =       MD5_HMAC_BLOCK_SIZE,
 152                .cra_module     =       THIS_MODULE,
 153        }
 154};
 155
 156static int __init md5_mod_init(void)
 157{
 158        return crypto_register_shash(&alg);
 159}
 160
 161static void __exit md5_mod_fini(void)
 162{
 163        crypto_unregister_shash(&alg);
 164}
 165
 166module_init(md5_mod_init);
 167module_exit(md5_mod_fini);
 168
 169MODULE_LICENSE("GPL");
 170MODULE_DESCRIPTION("MD5 Message Digest Algorithm");
 171
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