crypto/md5.c

   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 const u8 md5_zero_message_hash[MD5_DIGEST_SIZE] = {
  28         0xd4, 0x1d, 0x8c, 0xd9, 0x8f, 0x00, 0xb2, 0x04,
  29         0xe9, 0x80, 0x09, 0x98, 0xec, 0xf8, 0x42, 0x7e,
  30 };
  31 EXPORT_SYMBOL_GPL(md5_zero_message_hash);
  32
  33 /* XXX: this stuff can be optimized */
  34 static inline void le32_to_cpu_array(u32 *buf, unsigned int words)
  35 {
  36         while (words--) {
  37                 __le32_to_cpus(buf);
  38                 buf++;
  39         }
  40 }
  41
  42 static inline void cpu_to_le32_array(u32 *buf, unsigned int words)
  43 {
  44         while (words--) {
  45                 __cpu_to_le32s(buf);
  46                 buf++;
  47         }
  48 }
  49
  50 static inline void md5_transform_helper(struct md5_state *ctx)
  51 {
  52         le32_to_cpu_array(ctx->block, sizeof(ctx->block) / sizeof(u32));
  53         md5_transform(ctx->hash, ctx->block);
  54 }
  55
  56 static int md5_init(struct shash_desc *desc)
  57 {
  58         struct md5_state *mctx = shash_desc_ctx(desc);
  59
  60         mctx->hash[0] = MD5_H0;
  61         mctx->hash[1] = MD5_H1;
  62         mctx->hash[2] = MD5_H2;
  63         mctx->hash[3] = MD5_H3;
  64         mctx->byte_count = 0;
  65
  66         return 0;
  67 }
  68
  69 static int md5_update(struct shash_desc *desc, const u8 *data, unsigned int len)
  70 {
  71         struct md5_state *mctx = shash_desc_ctx(desc);
  72         const u32 avail = sizeof(mctx->block) - (mctx->byte_count & 0x3f);
  73
  74         mctx->byte_count += len;
  75
  76         if (avail > len) {
  77                 memcpy((char *)mctx->block + (sizeof(mctx->block) - avail),
  78                        data, len);
  79                 return 0;
  80         }
  81
  82         memcpy((char *)mctx->block + (sizeof(mctx->block) - avail),
  83                data, avail);
  84
  85         md5_transform_helper(mctx);
  86         data += avail;
  87         len -= avail;
  88
  89         while (len >= sizeof(mctx->block)) {
  90                 memcpy(mctx->block, data, sizeof(mctx->block));
  91                 md5_transform_helper(mctx);
  92                 data += sizeof(mctx->block);
  93                 len -= sizeof(mctx->block);
  94         }
  95
  96         memcpy(mctx->block, data, len);
  97
  98         return 0;
  99 }
 100
 101 static int md5_final(struct shash_desc *desc, u8 *out)
 102 {
 103         struct md5_state *mctx = shash_desc_ctx(desc);
 104         const unsigned int offset = mctx->byte_count & 0x3f;
 105         char *p = (char *)mctx->block + offset;
 106         int padding = 56 - (offset + 1);
 107
 108         *p++ = 0x80;
 109         if (padding < 0) {
 110                 memset(p, 0x00, padding + sizeof (u64));
 111                 md5_transform_helper(mctx);
 112                 p = (char *)mctx->block;
 113                 padding = 56;
 114         }
 115
 116         memset(p, 0, padding);
 117         mctx->block[14] = mctx->byte_count << 3;
 118         mctx->block[15] = mctx->byte_count >> 29;
 119         le32_to_cpu_array(mctx->block, (sizeof(mctx->block) -
 120                           sizeof(u64)) / sizeof(u32));
 121         md5_transform(mctx->hash, mctx->block);
 122         cpu_to_le32_array(mctx->hash, sizeof(mctx->hash) / sizeof(u32));
 123         memcpy(out, mctx->hash, sizeof(mctx->hash));
 124         memset(mctx, 0, sizeof(*mctx));
 125
 126         return 0;
 127 }
 128
 129 static int md5_export(struct shash_desc *desc, void *out)
 130 {
 131         struct md5_state *ctx = shash_desc_ctx(desc);
 132
 133         memcpy(out, ctx, sizeof(*ctx));
 134         return 0;
 135 }
 136
 137 static int md5_import(struct shash_desc *desc, const void *in)
 138 {
 139         struct md5_state *ctx = shash_desc_ctx(desc);
 140
 141         memcpy(ctx, in, sizeof(*ctx));
 142         return 0;
 143 }
 144
 145 static struct shash_alg alg = {
 146         .digestsize     =       MD5_DIGEST_SIZE,
 147         .init           =       md5_init,
 148         .update         =       md5_update,
 149         .final          =       md5_final,
 150         .export         =       md5_export,
 151         .import         =       md5_import,
 152         .descsize       =       sizeof(struct md5_state),
 153         .statesize      =       sizeof(struct md5_state),
 154         .base           =       {
 155                 .cra_name       =       "md5",
 156                 .cra_flags      =       CRYPTO_ALG_TYPE_SHASH,
 157                 .cra_blocksize  =       MD5_HMAC_BLOCK_SIZE,
 158                 .cra_module     =       THIS_MODULE,
 159         }
 160 };
 161
 162 static int __init md5_mod_init(void)
 163 {
 164         return crypto_register_shash(&alg);
 165 }
 166
 167 static void __exit md5_mod_fini(void)
 168 {
 169         crypto_unregister_shash(&alg);
 170 }
 171
 172 module_init(md5_mod_init);
 173 module_exit(md5_mod_fini);
 174
 175 MODULE_LICENSE("GPL");
 176 MODULE_DESCRIPTION("MD5 Message Digest Algorithm");
 177 MODULE_ALIAS_CRYPTO("md5");