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checksum.cpp
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checksum.cpp
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#pragma once
#include "checksum.h"
unsigned int MD5_PseudoRandom( unsigned int nSeed )
{
MD5Context_t ctx;
unsigned char digest[MD5_DIGEST_LENGTH]; // The MD5 Hash
memset( &ctx, 0, sizeof( ctx ) );
MD5Init( &ctx );
MD5Update( &ctx, (unsigned char*)&nSeed, sizeof( nSeed ) );
MD5Final( digest, &ctx );
return *(unsigned int*)( digest + 6 ); // use 4 middle bytes for random value
}
void MD5Init( MD5Context_t *ctx )
{
ctx->buf[0] = 0x67452301;
ctx->buf[1] = 0xefcdab89;
ctx->buf[2] = 0x98badcfe;
ctx->buf[3] = 0x10325476;
ctx->bits[0] = 0;
ctx->bits[1] = 0;
}
// The four core functions - F1 is optimized somewhat
// #define F1(x, y, z) (x & y | ~x & z)
#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, data, s) \
( w += f(x, y, z) + data, w = w<<s | w>>(32-s), w += x )
static void MD5Transform( unsigned int buf[4], unsigned int const in[16] )
{
unsigned int a, b, c, d;
a = buf[0];
b = buf[1];
c = buf[2];
d = buf[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 );
buf[0] += a;
buf[1] += b;
buf[2] += c;
buf[3] += d;
}
void MD5Update( MD5Context_t *ctx, unsigned char const *buf, unsigned int len )
{
unsigned int t;
/* Update bitcount */
t = ctx->bits[0];
if ( ( ctx->bits[0] = t + ( (unsigned int)len << 3 ) ) < t )
ctx->bits[1]++; /* Carry from low to high */
ctx->bits[1] += len >> 29;
t = ( t >> 3 ) & 0x3f; /* Bytes already in shsInfo->data */
/* Handle any leading odd-sized chunks */
if ( t )
{
unsigned char *p = (unsigned char *)ctx->in + t;
t = 64 - t;
if ( len < t )
{
memcpy( p, buf, len );
return;
}
memcpy( p, buf, t );
//byteReverse(ctx->in, 16);
MD5Transform( ctx->buf, (unsigned int *)ctx->in );
buf += t;
len -= t;
}
/* Process data in 64-BYTE chunks */
while ( len >= 64 )
{
memcpy( ctx->in, buf, 64 );
//byteReverse(ctx->in, 16);
MD5Transform( ctx->buf, (unsigned int *)ctx->in );
buf += 64;
len -= 64;
}
/* Handle any remaining bytes of data. */
memcpy( ctx->in, buf, len );
}
void MD5Final( unsigned char digest[MD5_DIGEST_LENGTH], MD5Context_t *ctx )
{
unsigned count;
unsigned char *p;
/* Compute number of bytes mod 64 */
count = ( ctx->bits[0] >> 3 ) & 0x3F;
/* Set the first char of padding to 0x80. This is safe since there is
always at least one BYTE free */
p = ctx->in + count;
*p++ = 0x80;
/* Bytes of padding needed to make 64 bytes */
count = 64 - 1 - count;
/* Pad out to 56 mod 64 */
if ( count < 8 )
{
/* Two lots of padding: Pad the first block to 64 bytes */
memset( p, 0, count );
//byteReverse(ctx->in, 16);
MD5Transform( ctx->buf, (unsigned int *)ctx->in );
/* Now fill the next block with 56 bytes */
memset( ctx->in, 0, 56 );
}
else
{
/* Pad block to 56 bytes */
memset( p, 0, count - 8 );
}
//byteReverse(ctx->in, 14);
/* Append length in bits and transform */
( (unsigned int *)ctx->in )[14] = ctx->bits[0];
( (unsigned int *)ctx->in )[15] = ctx->bits[1];
MD5Transform( ctx->buf, (unsigned int *)ctx->in );
//byteReverse((unsigned char *) ctx->buf, 4);
memcpy( digest, ctx->buf, MD5_DIGEST_LENGTH );
memset( ctx, 0, sizeof( *ctx ) ); /* In case it's sensitive */
}