PHP 密码学类问题

Question

我在这个密码学课程方面遇到了一些问题。我是 PHP 新手，我敢肯定这是一个小的语法问题，但谁能指出我正确的方向？该代码目前根本不起作用。

这里是代码

密码学.php

class Cryptography
{
    # the key should be random binary, use scrypt, bcrypt or PBKDF2 to
    # convert a string into a key
    # key is specified using hexadecimal
    # use either 16, 24 or 32 byte keys for AES-128, 192
    # and 256 respectively
    private static $key = pack('H*', "I-AINT-SHOWING-YOU-MY-KEY-LOL");
    private static $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);

    public static function encrypt($plaintext)
    {
        # --- ENCRYPTION ---

        # create a random IV to use with CBC encoding
        $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);

        # creates a cipher text compatible with AES (Rijndael block size = 128)
        # to keep the text confidential 
        # only suitable for encoded input that never ends with value 00h
        # (because of default zero padding)
        $ciphertext = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $key, $plaintext, MCRYPT_MODE_CBC, $iv);

        # prepend the IV for it to be available for decryption
        $ciphertext = $iv . $ciphertext;

        # encode the resulting cipher text so it can be represented by a string
        return base64_encode($ciphertext);
    }

    public static function decrypt($ciphertext_base64)
    {
        # --- DECRYPTION ---

        $ciphertext_dec = base64_decode($ciphertext_base64);

        # retrieves the IV, iv_size should be created using mcrypt_get_iv_size()
        $iv_dec = substr($ciphertext_dec, 0, $iv_size);

        # retrieves the cipher text (everything except the $iv_size in the front)
        $ciphertext_dec = substr($ciphertext_dec, $iv_size);

        # may remove 00h valued characters from end of plain text
        return mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key, $ciphertext_dec, MCRYPT_MODE_CBC, $iv_dec);
    } 
}

Test.php

    require_once('Cryptography.php');

    $text = 'This is the string I am going to encrypt' . "\n\n";

    echo $text;

    $encrypted_text = Cryptography::encrypt($text);

    echo "{$encrypted_text}\n\n";

    $decrypted_text = Cryptography::decrypt($encrypted_text);

    echo "{$decrypted_text}\n\n";

Answer 1

static $key 不能是另一个函数的输出。必须是字面意思。您可以将$key 更改为某个函数，例如create_key() 并返回pack() 输出。然后必须将所有$key 更改为self::create_key()。同样关注$iv_size，也需要转换成self::get_iv_size()。

private static function create_key(){
    return pack('H*', "I-AINT-SHOWING-YOU-MY-KEY-LOL");
}
private static function get_iv_size(){ 
    return mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
}