xor_cipher.cpp File Reference

Implementation of XOR cipher algorithm. More...

#include <iostream>
#include <string>
#include <cassert>

Include dependency graph for xor_cipher.cpp:

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Namespaces
namespace	ciphers
	Algorithms for encryption and decryption.
namespace	XOR
	Functions for XOR cipher algorithm.

Functions
std::string	ciphers::XOR::encrypt (const std::string &text, const int &key)
std::string	ciphers::XOR::decrypt (const std::string &text, const int &key)
void	test ()
int	main ()

Detailed Description

Implementation of XOR cipher algorithm.

In cryptography, the simple XOR cipher is a type of additive cipher, an encryption algorithm that operates according to the principles:

• \(A {\oplus} 0 = A\)
• \(A {\oplus} A = 0\)
• \( (A {\oplus} B) {\oplus} C = A {\oplus} (B {\oplus} C)\)
• \( (B {\oplus} A) {\oplus} B = B {\oplus} 0 = B \)

where \(\oplus\) symbol denotes the exclusive disjunction (XOR) operation. This operation is sometimes called modulus 2 addition (or subtraction, which is identical). With this logic, a string of text can be encrypted by applying the bitwise XOR operator to every character using a given key. To decrypt the output, merely reapplying the XOR function with the key will remove the cipher.

Algorithm

Choose the key for encryption and apply XOR operation to each character of a string. Reapplying XOR operation to each character of encrypted string will give original string back.

Note

This program implements XOR Cipher for string with ASCII characters.

Author

Deep Raval

Definition in file xor_cipher.cpp.

Function Documentation

decrypt()

std::string ciphers::XOR::decrypt	(	const std::string &	text,
		const int &	key )

Decrypt given text using XOR cipher.

Parameters

text	text to be encrypted
key	to be used for decryption

Returns

new decrypted text

Definition at line 61 of file xor_cipher.cpp.

                                                                  {
            std::string decrypted_text = ""; // Empty string to store decrypted text
            for (auto &c : text) { // Going through each character
                char decrypted_char = char(c ^ key); // Applying decryption
                decrypted_text += decrypted_char; // Appending decrypted character
            }
            return decrypted_text; // Returning decrypted text
        }

encrypt()

std::string ciphers::XOR::encrypt	(	const std::string &	text,
		const int &	key )

Encrypt given text using XOR cipher.

Parameters

text	text to be encrypted
key	to be used for encyption

Returns

new encrypted text

Definition at line 47 of file xor_cipher.cpp.

                                                                  {
            std::string encrypted_text = ""; // Empty string to store encrypted text
            for (auto &c: text) { // Going through each character
                char encrypted_char = char(c ^ key); // Applying encyption
                encrypted_text += encrypted_char; // Appending encrypted character
            }
            return encrypted_text; // Returning encrypted text
        }

main()

int main

(

void

)

Driver Code

Definition at line 95 of file xor_cipher.cpp.

           {
    // Testing
    test();
    return 0;
}

test()

void test

(

)

Function to test above algorithm

Definition at line 75 of file xor_cipher.cpp.

            {
    // Test 1
    std::string text1 = "Whipalsh! : Do watch this movie...";
    std::string encrypted1 = ciphers::XOR::encrypt(text1, 17);
    std::string decrypted1 = ciphers::XOR::decrypt(encrypted1, 17);
    assert(text1 == decrypted1);
    std::cout << "Original text : " << text1;
    std::cout << " , Encrypted text (with key = 17) : " << encrypted1;
    std::cout << " , Decrypted text : "<< decrypted1 << std::endl;
    // Test 2
    std::string text2 = "->Valar M0rghulis<-";
    std::string encrypted2 = ciphers::XOR::encrypt(text2, 29);
    std::string decrypted2 = ciphers::XOR::decrypt(encrypted2, 29);
    assert(text2 == decrypted2);
    std::cout << "Original text : " << text2;
    std::cout << " , Encrypted text (with key = 29) : " << encrypted2;
    std::cout << " , Decrypted text : "<< decrypted2 << std::endl;
}