src/Keypair.php
public function getPublicKeyChecksum()
    {
        $checksumBytes = substr($this->getPublicKeyBytes(), -2);

        $unpacked = unpack('v', $checksumBytes);

        return array_shift($unpacked);
    }
public function getPublicKeyChecksum()
    {
        $checksumBytes = substr($this->getPublicKeyBytes(), -2);

        $unpacked = unpack('v', $checksumBytes);

        return array_shift($unpacked);
    }
Returns the raw bytes of the checksum for the public key

@return string