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Linux/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");
178 

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