How to Securely Encrypt and Decrypt Files Using AES256 in PHP?

Encrypting / Decrypting Files with Mcrypt

Mcrypt has been deprecated and is no longer recommended for use. This article presents an alternative approach using openssl.

AES256 Encryption and Decryption

This updated implementation employs AES256 for encryption, providing a significantly higher level of security compared to Mcrypt. Below is the revised code:

class AES256Encryption
{
    public const BLOCK_SIZE = 8;
    public const IV_LENGTH = 16;
    public const CIPHER = 'AES256';

    public static function generateIv(bool $allowLessSecure = false): string
    {
        // Logic to generate a secure initialization vector
    }

    protected static function getPaddedText(string $plainText): string
    {
        // Logic to pad the plaintext to a multiple of the block size
    }

    public static function encrypt(string $plainText, string $key, string $iv): string
    {
        // Logic to encrypt the plaintext using AES256
    }

    public static function decrypt(string $encryptedText, string $key, string $iv): string
    {
        // Logic to decrypt the ciphertext using AES256
    }
}

Usage:

$text = 'Your plaintext here';
$key = 'Your encryption key';
$iv = AES256Encryption::generateIv();
$encryptedText = AES256Encryption::encrypt($text, $key, $iv);
$decryptedText = AES256Encryption::decrypt($encryptedText, $key, $iv);

// Print the results
echo "Original Text: $text" . PHP_EOL;
echo "Encrypted: $encryptedText" . PHP_EOL;
echo "Decrypted: $decryptedText" . PHP_EOL;

This code demonstrates the encryption and decryption of plaintext using AES256, ensuring secure data handling.

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