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 <linux/init.h>
  20 #include <linux/module.h>
  21 #include <linux/string.h>
  22 #include <linux/types.h>
  23 #include <linux/cryptohash.h>
  24 #include <asm/byteorder.h>
  25
  26 #define MD5_DIGEST_SIZE         16
  27 #define MD5_HMAC_BLOCK_SIZE     64
  28 #define MD5_BLOCK_WORDS         16
  29 #define MD5_HASH_WORDS          4
  30
  31 struct md5_ctx {
  32         u32 hash[MD5_HASH_WORDS];
  33         u32 block[MD5_BLOCK_WORDS];
  34         u64 byte_count;
  35 };
  36
  37 /* XXX: this stuff can be optimized */
  38 static inline void le32_to_cpu_array(u32 *buf, unsigned int words)
  39 {
  40         while (words--) {
  41                 __le32_to_cpus(buf);
  42                 buf++;
  43         }
  44 }
  45
  46 static inline void cpu_to_le32_array(u32 *buf, unsigned int words)
  47 {
  48         while (words--) {
  49                 __cpu_to_le32s(buf);
  50                 buf++;
  51         }
  52 }
  53
  54 static inline void md5_transform_helper(struct md5_ctx *ctx)
  55 {
  56         le32_to_cpu_array(ctx->block, sizeof(ctx->block) / sizeof(u32));
  57         md5_transform(ctx->hash, ctx->block);
  58 }
  59
  60 static int md5_init(struct shash_desc *desc)
  61 {
  62         struct md5_ctx *mctx = shash_desc_ctx(desc);
  63
  64         mctx->hash[0] = 0x67452301;
  65         mctx->hash[1] = 0xefcdab89;
  66         mctx->hash[2] = 0x98badcfe;
  67         mctx->hash[3] = 0x10325476;
  68         mctx->byte_count = 0;
  69
  70         return 0;
  71 }
  72
  73 static int md5_update(struct shash_desc *desc, const u8 *data, unsigned int len)
  74 {
  75         struct md5_ctx *mctx = shash_desc_ctx(desc);
  76         const u32 avail = sizeof(mctx->block) - (mctx->byte_count & 0x3f);
  77
  78         mctx->byte_count += len;
  79
  80         if (avail > len) {
  81                 memcpy((char *)mctx->block + (sizeof(mctx->block) - avail),
  82                        data, len);
  83                 return 0;
  84         }
  85
  86         memcpy((char *)mctx->block + (sizeof(mctx->block) - avail),
  87                data, avail);
  88
  89         md5_transform_helper(mctx);
  90         data += avail;
  91         len -= avail;
  92
  93         while (len >= sizeof(mctx->block)) {
  94                 memcpy(mctx->block, data, sizeof(mctx->block));
  95                 md5_transform_helper(mctx);
  96                 data += sizeof(mctx->block);
  97                 len -= sizeof(mctx->block);
  98         }
  99
 100         memcpy(mctx->block, data, len);
 101
 102         return 0;
 103 }
 104
 105 static int md5_final(struct shash_desc *desc, u8 *out)
 106 {
 107         struct md5_ctx *mctx = shash_desc_ctx(desc);
 108         const unsigned int offset = mctx->byte_count & 0x3f;
 109         char *p = (char *)mctx->block + offset;
 110         int padding = 56 - (offset + 1);
 111
 112         *p++ = 0x80;
 113         if (padding < 0) {
 114                 memset(p, 0x00, padding + sizeof (u64));
 115                 md5_transform_helper(mctx);
 116                 p = (char *)mctx->block;
 117                 padding = 56;
 118         }
 119
 120         memset(p, 0, padding);
 121         mctx->block[14] = mctx->byte_count << 3;
 122         mctx->block[15] = mctx->byte_count >> 29;
 123         le32_to_cpu_array(mctx->block, (sizeof(mctx->block) -
 124                           sizeof(u64)) / sizeof(u32));
 125         md5_transform(mctx->hash, mctx->block);
 126         cpu_to_le32_array(mctx->hash, sizeof(mctx->hash) / sizeof(u32));
 127         memcpy(out, mctx->hash, sizeof(mctx->hash));
 128         memset(mctx, 0, sizeof(*mctx));
 129
 130         return 0;
 131 }
 132
 133 static struct shash_alg alg = {
 134         .digestsize     =       MD5_DIGEST_SIZE,
 135         .init           =       md5_init,
 136         .update         =       md5_update,
 137         .final          =       md5_final,
 138         .descsize       =       sizeof(struct md5_ctx),
 139         .base           =       {
 140                 .cra_name       =       "md5",
 141                 .cra_flags      =       CRYPTO_ALG_TYPE_SHASH,
 142                 .cra_blocksize  =       MD5_HMAC_BLOCK_SIZE,
 143                 .cra_module     =       THIS_MODULE,
 144         }
 145 };
 146
 147 static int __init md5_mod_init(void)
 148 {
 149         return crypto_register_shash(&alg);
 150 }
 151
 152 static void __exit md5_mod_fini(void)
 153 {
 154         crypto_unregister_shash(&alg);
 155 }
 156
 157 module_init(md5_mod_init);
 158 module_exit(md5_mod_fini);
 159
 160 MODULE_LICENSE("GPL");
 161 MODULE_DESCRIPTION("MD5 Message Digest Algorithm");