How to Securely Encrypt and Decrypt Files Using OpenSSL and a Custom PHP Class?

How to Encrypt and Decrypt Files Using Mcrypt

Mcrypt, a popular encryption library, has been discontinued and is no longer recommended for use. For this reason, we will explore an alternative encryption technique using the OpenSSL extension.

Creating a Custom Encryption Class

To encapsulate the encryption process, we define a custom class, AES256Encryption, which leverages OpenSSL's AES-256 algorithm.

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

    //... Encryption and Decryption Methods ...
}

Usage

$text = 'Plain text to be encrypted';
$key = 'Encryption key';
$iv = AES256Encryption::generateIv();  // Generates a random initialization vector (IV)
$encryptedText = AES256Encryption::encrypt($text, $key, $iv);  // Encrypts the text
$decryptedText = AES256Encryption::decrypt($encryptedText, $key, $iv);  // Decrypts the encrypted text

Sample Output

Original Text: Plain text to be encrypted
Encrypted: Encrypted ciphertext
Decrypted: Plain text to be encrypted

Other Considerations

• IV Generation: Ensure secure generation of the initialization vector (IV) using AES256Encryption::generateIv().
• Padding: The input text is padded to a multiple of the block size to ensure proper encryption.
• Base64 Encoding: The encrypted and decrypted data is base64-encoded for convenience.
• Exceptions: Error handling is included to report potential issues during encryption or decryption.

This updated approach using OpenSSL provides a secure and reliable method for encrypting and decrypting files and data using the latest encryption standards.

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