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#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "sha1.h"
Sha1::Sha1() :
H0( 0x67452301 ),
H1( 0xefcdab89 ),
H2( 0x98badcfe ),
H3( 0x10325476 ),
H4( 0xc3d2e1f0 ),
unprocessedBytes( 0 ),
size( 0 )
{
}
Sha1::~Sha1()
{
}
void Sha1::process()
{
int t;
uint32_t a, b, c, d, e, K, f, W[80];
// starting values
a = H0;
b = H1;
c = H2;
d = H3;
e = H4;
// copy and expand the message block
for( t = 0; t < 16; t++ ) W[t] = (bytes[t*4] << 24)
+(bytes[t*4 + 1] << 16)
+(bytes[t*4 + 2] << 8)
+ bytes[t*4 + 3];
for(; t< 80; t++ ) W[t] = lrot( W[t-3]^W[t-8]^W[t-14]^W[t-16], 1 );
/* main loop */
uint32_t temp;
for( t = 0; t < 80; t++ )
{
if( t < 20 ) {
K = 0x5a827999;
f = (b & c) | ((~b) & d);
} else if( t < 40 ) {
K = 0x6ed9eba1;
f = b ^ c ^ d;
} else if( t < 60 ) {
K = 0x8f1bbcdc;
f = (b & c) | (b & d) | (c & d);
} else {
K = 0xca62c1d6;
f = b ^ c ^ d;
}
temp = lrot(a,5) + f + e + W[t] + K;
e = d;
d = c;
c = lrot(b,30);
b = a;
a = temp;
//printf( "t=%d %08x %08x %08x %08x %08x\n",t,a,b,c,d,e );
}
/* add variables */
H0 += a;
H1 += b;
H2 += c;
H3 += d;
H4 += e;
//printf( "Current: %08x %08x %08x %08x %08x\n",H0,H1,H2,H3,H4 );
/* all bytes have been processed */
unprocessedBytes = 0;
}
void Sha1::update( const char* data, int num )
{
// add these bytes to the running total
size += num;
// repeat until all data is processed
while( num > 0 )
{
// number of bytes required to complete block
int needed = 64 - unprocessedBytes;
// number of bytes to copy (use smaller of two)
int toCopy = (num < needed) ? num : needed;
// Copy the bytes
memcpy( bytes + unprocessedBytes, data, toCopy );
// Bytes have been copied
num -= toCopy;
data += toCopy;
unprocessedBytes += toCopy;
// there is a full block
if( unprocessedBytes == 64 ) process();
}
}
unsigned char* Sha1::getDigest()
{
// save the message size
uint32_t totalBitsL = size << 3;
uint32_t totalBitsH = size >> 29;
// add 0x80 to the message
update( "\x80", 1 );
unsigned char footer[64] = {
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
// block has no room for 8-byte filesize, so finish it
if( unprocessedBytes > 56 )
update( (char*)footer, 64 - unprocessedBytes);
// how many zeros do we need
int neededZeros = 56 - unprocessedBytes;
// store file size (in bits) in big-endian format
toBigEndian( totalBitsH, footer + neededZeros );
toBigEndian( totalBitsL, footer + neededZeros + 4 );
// finish the final block
update( (char*)footer, neededZeros + 8 );
// allocate memory for the digest bytes
unsigned char* digest = new unsigned char[20];
// copy the digest bytes
toBigEndian( H0, digest );
toBigEndian( H1, digest + 4 );
toBigEndian( H2, digest + 8 );
toBigEndian( H3, digest + 12 );
toBigEndian( H4, digest + 16 );
// return the digest
return digest;
}
uint32_t Sha1::lrot( uint32_t x, int bits )
{
return (x<<bits) | (x>>(32 - bits));
};
void Sha1::toBigEndian( uint32_t num, unsigned char* byte )
{
byte[0] = (unsigned char)(num>>24);
byte[1] = (unsigned char)(num>>16);
byte[2] = (unsigned char)(num>>8);
byte[3] = (unsigned char)num;
}
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