LockrAes256CbcSha256KeyWrapper.php in Lockr 7.3

Namespace

Lockr\KeyWrapper

File

vendor/lockr/lockr/src/KeyWrapper/LockrAes256CbcSha256KeyWrapper.php

<?php

namespace Lockr\KeyWrapper;

class LockrAes256CbcSha256KeyWrapper implements KeyWrapperInterface {
  const PREFIX = '$1$';
  const METHOD = 'aes-256-cbc';
  const KEY_LEN = 32;
  const IV_LEN = 16;
  const HMAC_LEN = 32;

  /**
   * {@inheritdoc}
   */
  public static function enabled() {
    return function_exists('openssl_encrypt');
  }

  /**
   * {@inheritdoc}
   */
  public static function encrypt($plaintext, $key = null) {
    if (is_null($key)) {
      $key = random_bytes(self::KEY_LEN);
    }
    $iv = random_bytes(self::IV_LEN);
    return self::doEncrypt($plaintext, $key, $iv);
  }

  /**
   * {@inheritdoc}
   */
  public static function reencrypt($plaintext, $wrapping_key) {
    $wrapping_key = substr($wrapping_key, strlen(self::PREFIX));
    $wrapping_key = base64_decode($wrapping_key);
    $iv = random_bytes(self::IV_LEN);
    return self::doEncrypt($plaintext, $wrapping_key, $iv);
  }

  /**
   * {@inheritdoc}
   */
  public static function decrypt($encoded_cipherdata, $wrapping_key) {
    $raw_wrapping_key = substr($wrapping_key, strlen(self::PREFIX));
    $raw_wrapping_key = base64_decode($raw_wrapping_key);
    $key_data = hash('sha512', $raw_wrapping_key, true);
    $enc_key = substr($key_data, 0, self::KEY_LEN);
    $hmac_key = substr($key_data, self::KEY_LEN);
    $cipherdata = base64_decode($encoded_cipherdata);
    $iv = substr($cipherdata, 0, self::IV_LEN);
    $hmac0 = substr($cipherdata, -self::HMAC_LEN);
    $ciphertext = substr($cipherdata, self::IV_LEN, -self::HMAC_LEN);
    $hmac1 = self::hmac($iv, $ciphertext, $hmac_key);
    if (!hash_equals($hmac0, $hmac1)) {
      return LockrAes256CbcSha256RawKeyWrapper::decrypt($encoded_cipherdata, $wrapping_key);
    }
    $plaintext = openssl_decrypt($ciphertext, self::METHOD, $enc_key, OPENSSL_RAW_DATA, $iv);
    return $plaintext;
  }
  protected static function doEncrypt($plaintext, $key, $iv) {
    $key_data = hash('sha512', $key, true);
    $enc_key = substr($key_data, 0, self::KEY_LEN);
    $hmac_key = substr($key_data, self::KEY_LEN);
    $ciphertext = openssl_encrypt($plaintext, self::METHOD, $enc_key, OPENSSL_RAW_DATA, $iv);
    $hmac = self::hmac($iv, $ciphertext, $hmac_key);
    return [
      'ciphertext' => base64_encode($iv . $ciphertext . $hmac),
      'encoded' => self::PREFIX . base64_encode($key),
    ];
  }
  protected static function hmac($iv, $ciphertext, $key) {
    $data = self::PREFIX . self::METHOD . $iv . $ciphertext;
    return hash_hmac('sha256', $data, $key, true);
  }

}

// ex: ts=4 sts=4 sw=4 et:

Classes

Name	Description
LockrAes256CbcSha256KeyWrapper