Quelle md5.c Sprache: C

/*
* Cryptographic API.
*
* MD5 Message Digest Algorithm (RFC1321).
*
* Derived from cryptoapi implementation, originally based on the
* public domain implementation written by Colin Plumb in 1993.
*
* Copyright (c) Cryptoapi developers.
* Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
*/
#include <crypto/internal/hash.h>
#include <crypto/md5.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/string.h>

const u8 md5_zero_message_hash[MD5_DIGEST_SIZE] = {
0xd4, 0x1d, 0x8c, 0xd9, 0x8f, 0x00, 0xb2, 0x04,
0xe9, 0x80, 0x09, 0x98, 0xec, 0xf8, 0x42, 0x7e,
};
EXPORT_SYMBOL_GPL(md5_zero_message_hash);

#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))

#define MD5STEP(f, w, x, y, z, in, s) \
(w += f(x, y, z) + in, w = (w<<s | w>>(32-s)) + x)

static void md5_transform(__u32 *hash, __u32 const *in)
{
u32 a, b, c, d;

a = hash[0];
b = hash[1];
c = hash[2];
d = hash[3];

MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);

MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);

MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);

MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);

hash[0] += a;
hash[1] += b;
hash[2] += c;
hash[3] += d;
}

static inline void md5_transform_helper(struct md5_state *ctx,
     u32 block[MD5_BLOCK_WORDS])
{
le32_to_cpu_array(block, MD5_BLOCK_WORDS);
md5_transform(ctx->hash, block);
}

static int md5_init(struct shash_desc *desc)
{
struct md5_state *mctx = shash_desc_ctx(desc);

mctx->hash[0] = MD5_H0;
mctx->hash[1] = MD5_H1;
mctx->hash[2] = MD5_H2;
mctx->hash[3] = MD5_H3;
mctx->byte_count = 0;

return 0;
}

static int md5_update(struct shash_desc *desc, const u8 *data, unsigned int len)
{
struct md5_state *mctx = shash_desc_ctx(desc);
u32 block[MD5_BLOCK_WORDS];

mctx->byte_count += len;
do {
  memcpy(block, data, sizeof(block));
  md5_transform_helper(mctx, block);
  data += sizeof(block);
  len -= sizeof(block);
} while (len >= sizeof(block));
memzero_explicit(block, sizeof(block));
mctx->byte_count -= len;
return len;
}

static int md5_finup(struct shash_desc *desc, const u8 *data, unsigned int len,
       u8 *out)
{
struct md5_state *mctx = shash_desc_ctx(desc);
u32 block[MD5_BLOCK_WORDS];
unsigned int offset;
int padding;
char *p;

memcpy(block, data, len);

offset = len;
p = (char *)block + offset;
padding = 56 - (offset + 1);

*p++ = 0x80;
if (padding < 0) {
  memset(p, 0x00, padding + sizeof (u64));
  md5_transform_helper(mctx, block);
  p = (char *)block;
  padding = 56;
}

memset(p, 0, padding);
mctx->byte_count += len;
block[14] = mctx->byte_count << 3;
block[15] = mctx->byte_count >> 29;
le32_to_cpu_array(block, (sizeof(block) - sizeof(u64)) / sizeof(u32));
md5_transform(mctx->hash, block);
memzero_explicit(block, sizeof(block));
cpu_to_le32_array(mctx->hash, sizeof(mctx->hash) / sizeof(u32));
memcpy(out, mctx->hash, sizeof(mctx->hash));

return 0;
}

static struct shash_alg alg = {
.digestsize = MD5_DIGEST_SIZE,
.init  = md5_init,
.update  = md5_update,
.finup  = md5_finup,
.descsize = MD5_STATE_SIZE,
.base  = {
  .cra_name  = "md5",
  .cra_driver_name = "md5-generic",
  .cra_flags  = CRYPTO_AHASH_ALG_BLOCK_ONLY,
  .cra_blocksize  = MD5_HMAC_BLOCK_SIZE,
  .cra_module  = THIS_MODULE,
}
};

static int __init md5_mod_init(void)
{
return crypto_register_shash(&alg);
}

static void __exit md5_mod_fini(void)
{
crypto_unregister_shash(&alg);
}

module_init(md5_mod_init);
module_exit(md5_mod_fini);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("MD5 Message Digest Algorithm");
MODULE_ALIAS_CRYPTO("md5");

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