protected function sendGetPin()
    {
        $foundPin = '';

        if (is_array($this->currentPin)) {
            $keyIdLength = mb_strlen($this->currentPin['keyId'], '8bit');

            // search for the pin
            foreach ($this->pins as $_keyId => $pin) {
                // Warning: GnuPG 2.1 asks 3 times for passphrase if it is invalid
                $keyId        = $this->currentPin['keyId'];
                $_keyIdLength = mb_strlen($_keyId, '8bit');

                // Get last X characters of key identifier to compare
                // Most GnuPG versions use 8 characters, but recent ones can use 16,
                // We support 8 for backward compatibility
                if ($keyIdLength < $_keyIdLength) {
                    $_keyId = mb_substr($_keyId, -$keyIdLength, $keyIdLength, '8bit');
                } else if ($keyIdLength > $_keyIdLength) {
                    $keyId = mb_substr($keyId, -$_keyIdLength, $_keyIdLength, '8bit');
                }

                if ($_keyId === $keyId) {
                    $foundPin = $pin;
                    break;
                }
            }
        }

        return $this
            ->send($this->getData($foundPin))
            ->send($this->getOK());
    }