Root/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 */
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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