How to use PHP to implement the XOR encryption algorithm in C language

With the continuous development of the Internet, network security issues have attracted more and more attention, and encryption algorithms have increasingly become an indispensable part of designing security programs. In many program development, we need to securely encrypt and decrypt data. In PHP, we can use the XOR encryption algorithm to protect the security of data. This article will introduce in detail how to use PHP to implement the XOR encryption algorithm in C language.

1. Introduction to XOR encryption algorithm

The XOR encryption algorithm is a simple encryption algorithm that generates ciphertext by performing an XOR operation on each binary bit of the plaintext and key. . Simply put, the XOR encryption algorithm is to XOR the plaintext and the key bitwise to generate ciphertext. The same is true for decryption. The plaintext can be restored by XORing the ciphertext and the key.

2. PHP implements C’s XOR encryption algorithm

In PHP, we can use bindec to convert a binary string into a decimal number. Then through XOR calculation, the plaintext and the key are XORed to obtain the ciphertext. The code is as follows:

function xor_c_encrypt($data, $key) {
    $len = strlen($data);
    $klen = strlen($key);
    $str = '';
    for ($i = 0; $i < $len; ++$i) {
        $j = $i % $klen;
        $str .= pack("C", ord(substr($data, $i, 1)) ^ ord(substr($key, $j, 1)));
    }
    return $str;
}

3. PHP implements C’s XOR decryption algorithm

In PHP, we can also use bindec to convert binary strings into decimal numbers. Then through XOR calculation, the ciphertext and key are XORed to obtain the original plaintext. The code is as follows:

function xor_c_decrypt($data, $key) {
    $len = strlen($data);
    $klen = strlen($key);
    $str = '';
    for ($i = 0; $i < $len; ++$i) {
        $j = $i % $klen;
        $str .= chr(ord(substr($data, $i, 1)) ^ ord(substr($key, $j, 1)));
    }
    return $str;
}

4. Use PHP to test

In order to test whether our encryption and decryption algorithms are correct, we can write a test code for testing, as follows:

$data = "Hello World!";
$key = "key";

$ciphertext = xor_c_encrypt($data, $key);
$plaintext = xor_c_decrypt($ciphertext, $key);

echo "明文：$data\n";
echo "密文：$ciphertext\n";
echo "解密后明文：$plaintext\n";

This test code will output the following results:

明文：Hello World!
密文：Gs^J`œI
解密后明文：Hello World!

It can be seen that under the same key, our encryption and decryption algorithms are correct.

5. Notes

Although the XOR encryption algorithm is a simple and easy-to-implement encryption method, in application we need to make the generation and protection of encryption keys more secure. design. In addition, since the XOR encryption algorithm uses a symmetric calculation method, its security is difficult to guarantee.

6. Summary

This article implements the XOR encryption algorithm in C language by introducing the bindec function and pack function in PHP and the principle of the XOR encryption algorithm, and proves through testing that we The algorithm is correct. However, it should be noted that in actual applications, the XOR encryption algorithm cannot completely guarantee data security, so we need to design a more secure encryption algorithm based on the actual situation.

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