src/Google/AccessToken/Verify.php
private function setPhpsecConstants()
  {
    if (filter_var(getenv('GAE_VM'), FILTER_VALIDATE_BOOLEAN)) {
      if (!defined('MATH_BIGINTEGER_OPENSSL_ENABLED')) {
        define('MATH_BIGINTEGER_OPENSSL_ENABLED', true);
      }
      if (!defined('CRYPT_RSA_MODE')) {
        define('CRYPT_RSA_MODE', constant($this->getOpenSslConstant()));
      }
    }
  }
private function setPhpsecConstants()
  {
    if (filter_var(getenv('GAE_VM'), FILTER_VALIDATE_BOOLEAN)) {
      if (!defined('MATH_BIGINTEGER_OPENSSL_ENABLED')) {
        define('MATH_BIGINTEGER_OPENSSL_ENABLED', true);
      }
      if (!defined('CRYPT_RSA_MODE')) {
        define('CRYPT_RSA_MODE', constant($this->getOpenSslConstant()));
      }
    }
  }
phpseclib calls "phpinfo" by default, which requires special
whitelisting in the AppEngine VM environment. This function
sets constants to bypass the need for phpseclib to check phpinfo

@see phpseclib/Math/BigInteger
@see https://github.com/GoogleCloudPlatform/getting-started-php/issues/85