Can't get User Input with XOR encryption?

[RyRy]

#include <iostream>
#include <string>
#include <fstream>
#include <cstdlib>
#include <cstring>

int main(int argc, char* argv[])
{
    std::ifstream in;
    std::ofstream out;
    char* fileBuffer;
    std::string key;
    long fileSize = 0;

    if(argc < 3)
    {
        std::cout << "Usage:" << std::endl
            << "./xor file key" << std::endl;
        return 0;
    }

    in.open(argv[1]);

    if(!in.is_open())
    {
        std::cout << "Could not open file." << std::endl;
        return 0;
    }

    in.seekg(0, std::fstream::end);
    fileSize = in.tellg();
    in.seekg(0, std::fstream::beg);

    fileBuffer = new char[fileSize];
    memset(fileBuffer, 0, fileSize);
    in.read(fileBuffer, fileSize);
    in.close();

    out.open(argv[1]);

    key = argv[2];
    for(int i = 0; i < fileSize; i++)
    {
        fileBuffer[i] ^= key[i % key.length()];
    }

    out.write(fileBuffer, fileSize);

    delete [] fileBuffer;
    return 0;
}

This program uses Command line arguments to get the path and the encryption key. I'm trying to make it ask the user for these two things, and remove the need to go to command prompt to execute it. But when I use an encryption key that the user has inputted (using cin, into a string) I get a different encryption then if I would have inputted the SAME key in a command line argument.

How could I get the user to input the key, and get the same encryption that would have happened in command prompt?

[RyRy]

Anyone?

[Galik]

You might try adding the code to ask the user for the key alongside reading the key from the file and do a comparison to see how they are different.

[RyRy]

What do you mean? I don't want the key to be in the file.

[Galik]

I mean that you should do this to discover what the problem is. Ask the user for the key. Then read the same key from the file. Then compare the two. There must be something different about them and discovering what it is should help you solve the problem.

[RyRy]

Ok, when I read a file that contains "ó", the program reads it as "≤". Here's why I chose "ó" by the way:

http://en.wikipedia.org/wiki/XOR_cipher

The encryption key they used was 11110011 which = "ó".

I'm using it for testing purposes, because when put "Wiki" in the file, and encrypt it with that key "ó", I don't get the same results they have.

[Galik]

Ah, I see this is a manifestation of your other post: http://www.cplusplus.com/forum/general/27136/

This looks like a character encoding issue. I will hazard a guess that "ó" is being stored as a two byte UTF-8 character in the file. When you enter this from the keyboard it is possible that you may be only reading one of the two bytes or the terminal is performing some kind of code-page translation.

You could consider using more standard characters for your key. If its your terminal then I can't really help you with that. Its probably a Windows thing and it works fine on my Linux.

How are you reading the character? I presume you are inputting a std::string rather than a single char?

[Galik]

This is what your two codes look like on my system. The "ó" is a two byte character and the "≤" is a three byte:

ó length: 2
11000011 10110011 

≤ length: 3
11100010 10001001 10100100 

My system is using UTF-8 encoding.

[RyRy]

I guess I'm screwed aren't I? The encryption works fine when I type ó into a command line argument (I get the same encryption as the wikipedia article I posted). When I put my result into this site : http://www.roubaixinteractive.com/PlayGround/Binary_Conversion/Binary_to_Text.asp

I get the same binary as their answer.

If that means anything...

:(

[Galik]

Someone else might have a better understanding or your setup. I don't see why you need to use these out of range characters for you key though. Why not just use the English alphabet?

[Galik]

RyRy wrote:

I get the same binary as their answer.

Well that site does a conversion to ASCII before converting to binary. So it could be that your terminal it translating your character before feeding it to your program. I think you need to set the code page or the locale or something in the terminal before running the program.

Or install Linux which has an exceptionally sane shell.