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 /* XXX: this stuff can be optimized */
  28 static 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
  36 static 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
  44 static 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
  50 static int md5_init(struct shash_desc *desc)
  51 {
  52         struct md5_state *mctx = shash_desc_ctx(desc);
  53
  54         mctx->hash[0] = MD5_H0;
  55         mctx->hash[1] = MD5_H1;
  56         mctx->hash[2] = MD5_H2;
  57         mctx->hash[3] = MD5_H3;
  58         mctx->byte_count = 0;
  59
  60         return 0;
  61 }
  62
  63 static 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
  95 static 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
 123 static 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
 131 static 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
 139 static 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
 156 static int __init md5_mod_init(void)
 157 {
 158         return crypto_register_shash(&alg);
 159 }
 160
 161 static void __exit md5_mod_fini(void)
 162 {
 163         crypto_unregister_shash(&alg);
 164 }
 165
 166 module_init(md5_mod_init);
 167 module_exit(md5_mod_fini);
 168
 169 MODULE_LICENSE("GPL");
 170 MODULE_DESCRIPTION("MD5 Message Digest Algorithm");
 171 MODULE_ALIAS_CRYPTO("md5");