I don't get it? This Should work?!

[zhaoyun333]

Uhhhh you do know that characters are based on the 255 Ascii characters right? So when you have the string HELLO and your key is ZZZZZ:

HELLO
^ ZZZZZ
↕ ▼ ▬ §

What ^ actually does is it takes two binary numbers and takes the OR

10011011
^ 01101101
11110110

It sets a bit in the resulting value if either bit has a bit set at that position

So when you do this, you could get a number between 0 - 255 of which have different characters and such.

[why06]

Uhhhh you do know that characters are based on the 255 Ascii characters right? So when you have the string HELLO and your key is ZZZZZ:

HELLO
^ ZZZZZ
↕ ▼ ▬ §

What ^ actually does is it takes two binary numbers and takes the OR

10011011
^ 01101101
11110110

It sets a bit in the resulting value if either bit has a bit set at that position

So when you do this, you could get a number between 0 - 255 of which have different characters and such.

Yeh I go that. The problem is finding the key. I'll use your example:

10011011 - this was ur plaintext
11110110 - this was ur ciphertext
01101101 - XORed together they equal the key, but something is a little wrong with my encryption scheme, its creating letters that shouldn't have been there to start with.

[Hell_Demon]

I got it working why =D

#include <windows.h>
#include <iostream>
#include <fstream>
using namespace std;
void XOREncrypt(char *txt, char *key);

int main()
{
	char txt[50];
	char key[50];
	while(1)
	{
        cout<<"Enter the filename: ";
		cin >> txt;
		cout<<"Encryption Key: ";
		cin >> key;
		XOREncrypt(txt, key);
	}
    return 1;
}

void XOREncrypt(char *txt, char *key)
{
	ifstream ttext;
	ofstream tout;
	int j=0;
	ttext.open(txt);
	tout.open("outp.txt");
	char ch;
	while(ttext.get(ch))
	{
		tout.put((int(ch)^int(key[j])));
		j<int(strlen(key)-1)?j++:j=0;
	}
	tout.close();
	ttext.close();
}

bug fixed, theres probly more bugs, but the decrypted text was the same

[why06]

I got it working why =D


bug fixed, theres probly more bugs, but the decrypted text was the same

Thanks. I'll look into this and try to apply it to my own code, and find out what the problem might be.

[Hell_Demon]

Fully working code:

#include <iostream>
using namespace std;

void XOREncrypt(char *pfile, char *pkey); // Forward declaration

int main()
{
	char tmpfile[50];	// stores our filename
	char key[50];		// stores our encryption key
	while(1)			// Repeat for eternity :)
	{
		cout<<"Enter the file name: ";	// No need to explain
		cin>>tmpfile;					// ^
		cout<<"Encryption key: ";		// ^
		cin>>key;						// ^
		XOREncrypt(tmpfile, key);		// Call the XOREncrypt function
	}
	return 0;
}

void XOREncrypt(char *pfile, char *pkey)
{
	FILE *input, *output;				// File pointers <3
	input=fopen(pfile, "rb");			// open the input file(mode: read+binary)
	output=fopen("output.txt", "wb");	// open the output file(mode: write+bin)
	if(input != NULL && output != NULL) // if they both opened succesfully
	{
		unsigned char buffer[64];	// unsigned char buffer to unfuck our previous errors
									// Any size will do, it tries to read 64 bytes a time now
		size_t i, j, rdln;	// size_t because thats what fread returns
		i=0;j=0;rdln=0;		// init to 0
		do // do
		{
			rdln = fread(buffer, sizeof(*buffer),sizeof(buffer),input); // read 64 bytes from input
			for(i=0;i<rdln;++i)// 0 to the amount of chars we succesfully read from the input file
			{
				buffer[i] ^= pkey[j++]; // XOR with the key
				if(j==strlen(pkey)) // if j is the strlen of the key
				{
					j=0;			// reset it to 0
				}
			}
			fwrite(buffer, sizeof(*buffer), rdln, output); // XOR'd buffer -> output file
		} while(rdln==sizeof(buffer)); // while characters read == size of the buffer(64)
	}
	fclose(input); // close the input file
	fclose(output); // close the output file
}

using unsigned char fixed the issues.
signed char can contain values between -128 to +127
unsigned char can contain values between 0 and 256 which is what we want.

[zhaoyun333]

Plain string: Himynameismike
Key: hi
Encrypted string: 
 bunch of random symbols which for soem reason dosent let me c&p

[why06]

I will try this out when I have time. Unfortunately working on a paper now and preparing for finals, but the unsigned thing might be the fix.

[Hell_Demon]

I will try this out when I have time. Unfortunately working on a paper now and preparing for finals, but the unsigned thing might be the fix.

it is, the code I posted on the last page works fine for me(even able to encrypt and decrypt a 10mb MP3 file without problems )