id, err := hex.DecodeString(keyHex[:8])
	if err != nil {
		return err
	}
	key, err := hex.DecodeString(keyHex[8:])
	if err != nil {
		return err
	}
	// Verify that CRC is ok.
	want := binary.LittleEndian.Uint32(id)
	got := crc32.ChecksumIEEE(key)
	if want != got {
		return fmt.Errorf("Invalid key checksum, want %x, got %x", want, got)
	}

	stream, err := sio.AES_256_GCM.Stream(key)