Question

C++ XOR two strings.

I am trying to XOR two strings

00112233445566778899AABBCCDDEEFFAABB060606060606

and

4ca00fd6dbf1fb284ca00fd6dbf1fb284ca00fd6dbf1fb28

my program is giving me: SPTWPVSPT[X   q'&t'!"u#'t~u"#rPTTTVVT as a result

However, when i go to http://xor.pw/? and input the two hexadecimal strings in I get the result: 4cb12de59fa49d5fc439a56d172c15d7e61b09d0ddf7fd2e

what am I doing wrong in my program below?

// plaintext value here
string pthex = "00112233445566778899AABBCCDDEEFFAABB";
// IV value here
string sHex = "4ca00fd6dbf1fb28";
string PaddedPlainText = pthex + "060606060606"; //added the pad
//cout<<PaddedPlainText<<endl;
// the above hex valus should be passed in .

int PPTextLength = PaddedPlainText.length(); // length of plaintext
int BlockCounter = (PPTextLength / 16);      // number of blocks to process

cout<<"Pa: "<<PaddedPlainText<<endl;
cout<<"IV: "<<sHex<<endl;
cout<<"Blocks: "<<BlockCounter<<endl;

string XORval;
string vXOR;

for (int i=1; i<=BlockCounter; i++)
{
    cout<<"I is: "<< i<<endl;
    if (i == 1)
        for (int j=0;j<16;j++)
        {
            //cout<<sHex.at(j)<<" "<<PaddedPlainText.at(j)<<endl;
            XORval = sHex.at(j)^PaddedPlainText.at(j);
            vXOR.append(XORval);
            //cout<<XORval<<endl;
        }
    else if (i > 1)
        for (int j =((i*16)-16); j < (((i)*16));j++)
        {
           // cout<<"the value of i: "<<i<<" the valiue of j: "<<j<<endl;
           // cout<<sHex.at((j-((i*16)-16)))<<" "<<PaddedPlainText.at(j)<<endl;
            XORval = sHex.at((j-((i*16)-16)))^PaddedPlainText.at(j);
            vXOR.append(XORval);
           // cout<<vXOR<<endl;
        }
        cout<<vXOR<<endl;
}
return 0;
}

Answer 1

#include<sstream>

#include<iostream>

using namespace std;

int ConvertHexToInteger(char ch){

if(ch>='0' && ch<='9')

return(ch-48);

else if(ch>='A' && ch<='Z')

return(ch-55);

else

return(ch-87);

}

string XORtwoStrings(string A, string B){

std::stringstream xoredString;

for(int i=0;i<B.length();i++){

xoredString << hex << (ConvertHexToInteger(A[i])^ConvertHexToInteger(B[i]));

}

return xoredString.str();

}

int main(){

string a = "00112233445566778899AABBCCDDEEFFAABB060606060606";

string b = "4ca00fd6dbf1fb284ca00fd6dbf1fb284ca00fd6dbf1fb28";

cout<<"XOR of two Hex String is: " << endl;

cout<<XORtwoStrings(a,b)<<endl;

}
===============================================================================
See The Output


Thanks, let me know if there is any concern.

c4b301bb9697:Chegg kundrars vi XORstrings.cpp c4b301bb9697:Chegg kundrar$ ./a.out XOR of two Hex String is: 4cb12de59fa49d5fc439a56d172c15d7e61b09d0ddf7fd2e c4b301bb9697:Chegg kundrar$ AWO Ms e( be9dedf7fd2e