How Can I Securely Encrypt and Decrypt Files in PHP Using Modern Libraries?

Encrypting and Decrypting Files with Mcrypt: A Modern Approach

Introduction

Mcrypt, once a popular encryption library for PHP, has been deprecated and is no longer recommended for use. For secure and reliable file encryption, modern alternatives like OpenSSL or Sodium PHP provide robust solutions.

Encryption Function

Here's an updated encryption function using OpenSSL:

function encryptFile($fileData, $key)
{
    $iv = openssl_random_pseudo_bytes(openssl_cipher_iv_length('AES-256-CBC'));
    $encryptedData = openssl_encrypt($fileData, 'AES-256-CBC', $key, OPENSSL_RAW_DATA, $iv);
    return base64_encode($iv . $encryptedData);
}

Decryption Function

Similarly, the following decryption function utilizes the new library:

function decryptFile($encryptedData, $key)
{
    $ivSize = openssl_cipher_iv_length('AES-256-CBC');
    $iv = substr($encryptedData, 0, $ivSize);
    $encryptedData = substr($encryptedData, $ivSize);
    $decryptedData = openssl_decrypt($encryptedData, 'AES-256-CBC', $key, OPENSSL_RAW_DATA, $iv);
    return $decryptedData;
}

Usage

To encrypt a file, read its contents into a variable, call the encryptFile function with the contents and the encryption key, and save the encrypted data to the output file.

For decryption, read the encrypted file's contents into a variable, call the decryptFile function with the encrypted data and the decryption key, and write the decrypted data to the output file.

Conclusion

By leveraging modern encryption libraries, you can securely encrypt and decrypt files in PHP, ensuring the confidentiality and integrity of sensitive data.

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