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/* sha1.cpp
Copyright (c) 2005 Michael D. Leonhard
http://tamale.net/
This file is licensed under the terms described in the
accompanying LICENSE file.
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include "sha1.h"
// print out memory in hexadecimal
void SHA1::hexPrinter( unsigned char* c, int l )
{
assert( c );
assert( l > 0 );
while( l > 0 )
{
printf( " %02x", *c );
l--;
c++;
}
}
// circular left bit rotation. MSB wraps around to LSB
Uint32 SHA1::lrot( Uint32 x, int bits )
{
return (x<<bits) | (x>>(32 - bits));
};
// Save a 32-bit unsigned integer to memory, in big-endian order
void SHA1::storeBigEndianUint32( unsigned char* byte, Uint32 num )
{
assert( byte );
byte[0] = (unsigned char)(num>>24);
byte[1] = (unsigned char)(num>>16);
byte[2] = (unsigned char)(num>>8);
byte[3] = (unsigned char)num;
}
// Constructor *******************************************************
SHA1::SHA1()
{
// make sure that the data type is the right size
assert( sizeof( Uint32 ) * 5 == 20 );
// initialize
H0 = 0x67452301;
H1 = 0xefcdab89;
H2 = 0x98badcfe;
H3 = 0x10325476;
H4 = 0xc3d2e1f0;
unprocessedBytes = 0;
size = 0;
}
// Destructor ********************************************************
SHA1::~SHA1()
{
// erase data
H0 = H1 = H2 = H3 = H4 = 0;
for( int c = 0; c < 64; c++ ) bytes[c] = 0;
unprocessedBytes = size = 0;
}
// process ***********************************************************
void SHA1::process()
{
assert( unprocessedBytes == 64 );
//printf( "process: " ); hexPrinter( bytes, 64 ); printf( "\n" );
int t;
Uint32 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 temp;
for( t = 0; t < 80; t++ )
{
if( t < 20 ) {
K = 0x5a827999;
f = (b & c) | ((b ^ 0xFFFFFFFF) & d);//TODO: try using ~
} 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;
}
// addBytes **********************************************************
void SHA1::addBytes( const char* data, int num )
{
assert( data );
assert( num > 0 );
// 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;
assert( needed > 0 );
// 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();
}
}
// digest ************************************************************
unsigned char* SHA1::getDigest()
{
// save the message size
Uint32 totalBitsL = size << 3;
Uint32 totalBitsH = size >> 29;
// add 0x80 to the message
addBytes( "\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 )
addBytes( (char*)footer, 64 - unprocessedBytes);
assert( unprocessedBytes <= 56 );
// how many zeros do we need
int neededZeros = 56 - unprocessedBytes;
// store file size (in bits) in big-endian format
storeBigEndianUint32( footer + neededZeros , totalBitsH );
storeBigEndianUint32( footer + neededZeros + 4, totalBitsL );
// finish the final block
addBytes( (char*)footer, neededZeros + 8 );
// allocate memory for the digest bytes
unsigned char* digest = (unsigned char*)malloc( 20 );
// copy the digest bytes
storeBigEndianUint32( digest, H0 );
storeBigEndianUint32( digest + 4, H1 );
storeBigEndianUint32( digest + 8, H2 );
storeBigEndianUint32( digest + 12, H3 );
storeBigEndianUint32( digest + 16, H4 );
// return the digest
return digest;
}
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