AES-256-GCM w/ PHP 7.1+ OpenSSL

decrypt.php

<?php
public function decrypt($secret, $data)
{
    $secret = hex2bin($secret);
    $iv = base64_decode(substr($data, 0, 16), true);
    $data = base64_decode(substr($data, 16), true);
    $tag = substr($data, strlen($data) - 16);
    $data = substr($data, 0, strlen($data) - 16);

    try {
      return openssl_decrypt(
        $data,
        'aes-256-gcm',
        $secret,
        OPENSSL_RAW_DATA,
        $iv,
        $tag
      );
    } catch (\Exception $e) {
      return false;
    }
}

encrypt.php

<?php

public function encrypt($secret, $data)
{
  $secret = hex2bin($secret);
  $iv = random_bytes(12);
  $tag = '';

  $encrypted = openssl_encrypt(
    $data,
    'aes-256-gcm',
    $secret,
    OPENSSL_RAW_DATA,
    $iv,
    $tag,
    '',
    16
  );

  return base64_encode($iv) . base64_encode($encrypted . $tag);
}

Thanks a lot Evan, now I'will look for long file encryption.

Nice work, thank you!

Sorry about this dumb question but what is the purpose of using a hex string, please? Surely a hacker would know about hex2bin(), no?