RC5 Decrypt/Encrypt for Conquer game client

RC5.h

#ifndef RC5_H
#define RC5_H

#define RC5_32          32

#define RC5_12          12
#define RC5_SUB         (RC5_12*2 + 2)

#define RC5_16          16
#define RC5_KEY         (RC5_16/4)

const unsigned long RC5_PW32    = 0xB7E15163;
const unsigned long RC5_QW32    = 0x61C88647;

const unsigned char RC5PASSWORD_KEY[16] = { 0x3C, 0xDC, 0xFE, 0xE8, 0xC4, 0x54, 0xD6, 0x7E, 
                                            0x16, 0xA6, 0xF8, 0x1A, 0xE8, 0xD0, 0x38, 0xBE };
const unsigned char RC5BARPASSWORD_KEY[16] = {  0x44, 0xD0, 0xE2, 0xBA, 0x4A, 0x38, 0x14, 0x44, 
                                                0x64, 0xE0, 0x12, 0xAE, 0xDA, 0x56, 0x1C, 0xF8 };

////////////////////////////////////////////////////////////////////////////////////////////////

class   CRc5
{
public:
    void Rc5InitKey(const unsigned char bufKey[RC5_16]);
    void Rc5Encrypt(void* buf, int nLen8);
    void Rc5Decrypt(void* buf, int nLen8);

protected:
    unsigned long   m_bufKey[RC5_KEY];
    unsigned long   m_bufSub[RC5_SUB];
};

#endif // RC5_H

RC5.cpp

#include <string>
#include <assert.h>

#include "RC5.h"


unsigned long   rotate_left(unsigned long nData, unsigned long nCount);
unsigned long   rotate_right(unsigned long nData, unsigned long nCount);

void CRc5::Rc5InitKey(const unsigned char bufKey[RC5_16])
{
    try{
        memcpy(m_bufKey, bufKey, RC5_16);
    }catch(...) {
#ifdef  _DEBUG
        assert(!"InitRc5Key()");
#endif
    }
    /*for (int i = 0; i < 4; i++)
    m_bufKey[i] = (long)(bufKey[i * 4] + (bufKey[i * 4 + 1] << 8) + (bufKey[i * 4 + 2] << 16) + (bufKey[i * 4 + 3] << 24));
    m_bufSub[0] = RC5_PW32;*/
    m_bufSub[0] = RC5_PW32;
    for(int i = 1; i<26; i++)
    {
        m_bufSub[i] = m_bufSub[i-1] - RC5_QW32;
    }
    int             i, j;
    unsigned long   x, y;
    i = j = x = y = 0;
    for(int k = 0; k <=78; k++)
    {
        m_bufSub[i] = rotate_left((m_bufSub[i] + x + y), 3);
        x = m_bufSub[i];
        i = (i + 1) % 0x1开发者_开发技巧A;
        m_bufKey[j] = rotate_left((m_bufKey[j] + x + y), (x + y));
        y = m_bufKey[j];
        j = (j + 1) % 4;
    }
}


void CRc5::Rc5Encrypt(void* buf, int nLen8)
{
    assert(nLen8 % 8 == 0);
    nLen8 = (nLen8/8) * 8;
    if(nLen8 <= 0)
        return;

    unsigned long* bufData = (unsigned long*)buf;
    for(int k = 0; k < nLen8/8; k++)
    {
        unsigned long   a = bufData[2*k];
        unsigned long   b = bufData[2*k + 1];

        unsigned long   le  = a + m_bufSub[0];
        unsigned long   re  = b + m_bufSub[1];
        for(int i = 1; i <= 12; i++)
        {
            le = rotate_left((le ^ re), re) + m_bufSub[2*i];
            re = rotate_left((re ^ le), le) + m_bufSub[2*i + 1];
        }

        bufData[2*k]        = le;
        bufData[2*k + 1]    = re;
    }
}

////////////////////////////////////////////////////////////////////////////////////////////////
void CRc5::Rc5Decrypt(void* buf, int nLen8)
{
    assert(nLen8 % 8 == 0);
    nLen8 = (nLen8/8) * 8;
    if(nLen8 <= 0)
        return;

    unsigned long* bufData = (unsigned long*)buf;
    for(int k = 0; k < nLen8/8; k++)
    {
        unsigned long   ld  = bufData[2*k];
        unsigned long   rd  = bufData[2*k + 1];
        for(int i = 12; i >= 1; i--)
        {
            rd = rotate_right((rd - m_bufSub[2*i + 1]),  ld) ^ ld;
            ld = rotate_right((ld - m_bufSub[2*i]),  rd) ^ rd;
        }

        unsigned long   b = rd - m_bufSub[1];
        unsigned long   a = ld - m_bufSub[0];

        bufData[2*k]        = a;
        bufData[2*k + 1]    = b;
    }
}



unsigned long   rotate_left(unsigned long nData, unsigned long nCount)
{
     return (nData << (nCount & 0x1F) | nData >> 0x20 - (nCount & 0x1F));
}

////////////////////////////////////////////////////////////////////////////////////////////////
unsigned long   rotate_right(unsigned long nData, unsigned long nCount)
{
    return (nData << (nCount & 0x1F) | nData >> 0x20 - (nCount & 0x1F));
}

main.cpp

//all the stuff
char buf[4000];
            char acc[16];
            char psw[16];
            recv(sConnect,buf,sizeof(buf),0);
            //dec.Rc5InitKey(RC5PASSWORD_KEY);
            dec.Rc5Decrypt(buf,16);
            cout << buf;

why did i post it here i cant decrypt the buf which i get from the client (but we dont play this game!) yes i know but am sure that am doing something wrong inside the code so maybe someone was dealing with RC5 knows what am doing wrong , if not it's okey . thnx

---

Without having looked at your code in detail, I would imagine that you need to set up the key schedule before you can actually decrypt the buffer you've received.

---

Looks like rotate_left and rotate_right are the same, but they shouldn't be:

unsigned long rotate_left(unsigned long nData, unsigned long nCount) {
    return (nData << (nCount & 0x1F) | nData >> 0x20 - (nCount & 0x1F));
}

unsigned long rotate_right(unsigned long nData, unsigned long nCount) {
    return (nData << (nCount & 0x1F) | nData >> 0x20 - (nCount & 0x1F));
}

rotate_right should be:

unsigned long   rotate_right(unsigned long nData, unsigned long nCount)
{
    return (nData >> (nCount & 0x1F) | nData << 0x20 - (nCount & 0x1F));
}