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/* Starshatter OpenSource Distribution
Copyright (c) 1997-2004, Destroyer Studios LLC.
All Rights Reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
* Neither the name "Destroyer Studios" nor the names of its contributors
may be used to endorse or promote products derived from this software
without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
SUBSYSTEM: nGenEx.lib
FILE: Encrypt.cpp
AUTHOR: John DiCamillo
OVERVIEW
========
Simple Encryption / Decryption class
*/
#include "MemDebug.h"
#include "Encrypt.h"
// +--------------------------------------------------------------------+
void Print(const char* fmt, ...);
static long k[4] = {
0x3B398E26,
0x40C29501,
0x614D7630,
0x7F59409A
};
static void encypher(long* v)
{
DWORD y=v[0];
DWORD z=v[1];
DWORD sum=0;
DWORD delta=0x9e3779b9; // a key schedule constant
DWORD n=32; // num iterations
while (n-->0) { // basic cycle start
sum += delta;
y += (z<<4)+k[0] ^ z+sum ^ (z>>5)+k[1];
z += (y<<4)+k[2] ^ y+sum ^ (y>>5)+k[3];
}
v[0]=y;
v[1]=z;
}
static void decypher(long* v)
{
DWORD y=v[0];
DWORD z=v[1];
DWORD sum=0;
DWORD delta=0x9e3779b9; // a key schedule constant
DWORD n=32; // num iterations
sum=delta<<5;
while (n-->0) {
z-= (y<<4)+k[2] ^ y+sum ^ (y>>5)+k[3];
y-= (z<<4)+k[0] ^ z+sum ^ (z>>5)+k[1];
sum-=delta;
}
v[0]=y;
v[1]=z;
}
// +-------------------------------------------------------------------+
Text
Encryption::Encrypt(Text block)
{
int len = block.length();
if (len < 1)
return Text();
// pad to eight byte chunks
if (len & 0x7) {
len /= 8;
len *= 8;
len += 8;
}
BYTE* work = new(__FILE__,__LINE__) BYTE[len];
ZeroMemory(work, len);
CopyMemory(work, block.data(), block.length());
long* v = (long*) work;
for (int i = 0; i < len/8; i++) {
encypher(v);
v += 2;
}
Text cypher((const char*) work, len);
delete [] work;
return cypher;
}
// +-------------------------------------------------------------------+
Text
Encryption::Decrypt(Text block)
{
int len = block.length();
if (len & 0x7) {
Print("WARNING: attempt to decrypt odd length block (len=%d)\n", len);
return Text();
}
BYTE* work = new(__FILE__,__LINE__) BYTE[len];
CopyMemory(work, block.data(), len);
long* v = (long*) work;
for (int i = 0; i < len/8; i++) {
decypher(v);
v += 2;
}
Text clear((const char*) work, len);
delete [] work;
return clear;
}
// +-------------------------------------------------------------------+
static const char* codes = "abcdefghijklmnop";
Text
Encryption::Encode(Text block)
{
int len = block.length() * 2;
char* work = new(__FILE__,__LINE__) char[len + 1];
for (int i = 0; i < block.length(); i++) {
BYTE b = (BYTE) (block.data()[i]);
work[2*i] = codes[b>>4 & 0xf];
work[2*i+1] = codes[b & 0xf];
}
work[len] = 0;
Text code(work, len);
delete [] work;
return code;
}
// +-------------------------------------------------------------------+
Text
Encryption::Decode(Text block)
{
int len = block.length() / 2;
char* work = new(__FILE__,__LINE__) char[len + 1];
for (int i = 0; i < len; i++) {
char u = block[2*i];
char l = block[2*i + 1];
work[i] = (u - codes[0]) << 4 |
(l - codes[0]);
}
work[len] = 0;
Text clear(work, len);
delete [] work;
return clear;
}
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