In recent years, technological innovation has allowed a rapid development of Internet services used as the basis for numerous applications in the professional and personal fields. The development of home automation and the devices associated with it has brought about great changes in terms of eficiency, simplicity and energy saving: with a simple click today it is possible to turn the light, heating, television and more on or of. The purpose of this paper is to provide performance evaluations, at a simulation and experimental level, of blockchain and IoT technologies and their interactions, creating a truly decentralized system that can allow the control of temperature and air conditioning inside a home with the use of a smart contract.
technologies that allow any type of device - sensors,
mobile phones and more - to be connected and controlled via
In recent years, technological innovation has allowed a the Internet [
The aim of this paper is to provide performance perature detection, or a more complex management of
evaluations, at a simulation and experimental level, of data from the interconnection between multiple sensors
blockchain and IoT technologies and their interactions, within the smart home, it was necessary to implement a
creating a truly decentralized system that can allow the highly secure, private and autonomous system in order
control of temperature and of air conditioning inside a to avoid the third party access.
home with the use of a smart contract. The blockchain, a
decentralized and secure system that allows the exchange
of transactions, was initially created for use in the eco- 2. Use case and system design for
nomic sector - the exchange of Bitcoin - and used in a temperature control
second phase with Ethereum [
change information through radio communication technologies in the local area according to standard protocols. For each of the subsystems listed, the implementation choices made are described in greater detail below.
In order to create the system in Figure 1, it is necessary
to create a private blockchain network and define the
architecture of the systems for climate and temperature
control [
runs on Go Ethereum. The latter, once installed, is used via the terminal of the device in question. Go Ethereum can be downloaded for various operating systems, and in the case of MacOs it requires an additional tool called Homebrew for managing packages that are absent in it.
The intention of the work project is to create a private network made up of two diferent LAN nodes in which 300,000 Ether will then be allocated in a first account and 400,000 Ether in the second. The allocation of Ether to a particular account must be done within the genesis file. • Blockchain subsystem: Go ethereum, MetaMask, In order for the network to be installed and the nodes to
Remix; run, it is necessary to have a solid Internet connection • Sensor subsystem: thermostat and air condition- and that the devices are connected to the same router. ing activation. The sensors send real-time temperature data to the blockchain which is controlled 3.2. MetaMask implementation through the smart contract;; • Subsystem for sensor-end user communication: In the implementation of the private network it is assmart contract. The latter checks the temperature sumed that the MetaMask software is a Chrome extendata sent by the sensor and sends an alarm mes- sion, does not require any special installation software sage to the end user if the values are not within and that Paolo is equipped with a computer on which he the range decided by the user himself. If the tem- can access his wallet and check his Ether balance. The perature value is higher than the upper bound, use of MetaMask, as can easily be understood, requires the smart contract passes from a control phase to an Internet connection. In the work project this partican event creation phase: the air conditioning will ular technology is used to check the remaining balance be activated, the event will be stored within the following the various transactions that are carried out. blockchain in the form of transaction and Ether will be consumed. 20–25 3.3. Implementation of Remix 4.3. Creating a new account • Download of “go Ethereum for Mac” from the
oficial website; • Download Homebrew, a free and open source software package management system that simplifies the installation of a tool on the Apple MacOS operating system. For the Ethereum Homebrew network it is necessary to create the “bootstrap” node.
Remix was used to develop and test the smart contract code. The creation of the smart contract was preceded by a series of considerations on the intention it should have and how it would be possible to transform an idea into a practical act. The first phase of contract analysis involved the study of writing a smart contract and the creation of a guide for it (see Appendix - writing a smart contract). The second phase concerned the creation and implementation of the same. The objective of the work project was to generate a contract that was able to control the temperature values sent by the thermostat sensor in real time. The expectation of the smart contract is the following: the data is read at any time from the contract which is activated only when a value is lower or higher than a particular range. It was established that the value of the upper bound was 25 degrees and the lower bound was 19 degrees. A temperature below 19 degrees leads to the creation of an event: an alarm message is sent to the devices of the private Ethereum network and Paolo is notified. The event is stored. Similarly, a temperature above 25 degrees leads to the generation of an air conditioning activation event. In this case the smart contract interacts with both sensors: with the thermostat sensor for detecting the temperature and with the air conditioner sensor for its activation. An event is created which is also stored within the network.
LAN network were: • Creation of two folders, one on each device involved in the system configuration. The folder served as a reference path throughout the work project;
the next step was to configure the peer-to-peer network.
It was appropriate to use a single node - the “bootstrap” node - as a meeting point for the other peers. The latter must know its IP address and enode identifier to allow connection to other users of the network. It was then necessary to verify that the firewall configuration could allow UDP and TCP trafic on port 30303. To control the open ports, telnet was downloaded using the commands “brew tap theeternalsw0rd/telnet brew install telnet curl http://ftp.gnu.org/gnu/inetutils/inetutils- 1.9.4.tar.gz 4.6. Creation of smart contracts for the -o inetutils-1.9.4.tar.gz tar xvzf inetutils-1.9.4.tar.gz cd use case inetutils-1.9.4 ./configure make sudo make install”. Port 30303 was found to be closed. The reference port has The smart contract was created to allow the recovery of been added to the router settings. the temperature data sent by the sensor placed on the
The enode is defined following the generation of a thermostat. If the home temperature value is lower than key using the commands “–genkey=boot.key” and “– the lower bound defined by Paolo then the contract will nodekey=boot.key” (Figure 6). The IP address displayed issue an alarm message to the homeowner. If, otherwise, in the identifier must be replaced with the externally ac- the value of the room is higher than the value of the cessible IP in order to obtain the URL that can be used upper bound, an alarm message is sent to Paolo and the to connect the other peers. We chose to use the account air conditioning of the room in question is activated: “0x6106520baB278022355948516DC2bAfA2FC56a48” on • the constructor function is executed first within the “Simona” device as the bootnode. The “bootstrap” the contract and is unique; node is online. The mining procedure was started • “onlyOwner” is the name of the modifier, i.e. the with the command “geth –mine –minerthreads 1 – one who changes the behavior of a function. In rpc –rpcaddr 0.0.0.0 –rpcport “8545” –port “30303” – the case in question it is Paolo; rpccorsdomain “*” –networkid 15 - -datadir <path> – • require declares prerequisites for the function allow-insecure-unlock”. The information entered in this and checks that the conditions are verified before command refers to the characteristics of the private net- starting the subsequent lines of code; work previously illustrated. The extraction has begun. • “msg.sender” defines the address of the account
To connect the geth console, a new shell was that invoked the function; opened and the command “geth –datadir <path> attach • set I only allow Paolo to set the value of the funcipc:<path> /geth.ipc” was entered. Once the connection tion; was completed, it was possible to check the available ac- • it also guarantees that the blockchain is uncounts through “eth.accounts” and the bootnode balance changeable; with “eth.getBalance(“”)” Second node connection to the • get allows you to read the data set by the owner LAN network from the other nodes in the network.
To connect the node on “Paolo’s” computer to the bootnode, the first step was to initialize the previously created account with the same genesis file used for “Si- 4.7. Smart contract validation mona”. The command to use is the same as the network In order to validate the deployment of the contract, the initialization step, with the appropriate changes to the terminal sends a "warning" message due to the blockpath. Once the node was started, the “admin.nodeInfo” ing of the account on which the transaction is being command was executed on “Paolo’s” JavaScript console carried out. Before the smart contract can be valito find the identifier. The latter was then inserted into dated, the bootnode account must be unlocked with the the “admin.addPeer(“enode”)” command on the “Simona” “web3.personal.unlockAccount(“”, “password”, duration) console. The passage returned the value “true”, confirm- command. The command must return “true”. The coning the connection of the two nodes to each other. tract has been deployed: a new block in the private network has been created. The validation of the transaction 4.5. Network connection with MetaMask cost a quantity of gas paid by the account connected to the Remix network.
The MetaMask connection to the Ethereum private network was made with the node running. The first step was taken by creating a custom network in the Chrome extension, in particular by specifying the host name and port used. At a later stage, the network accounts were entered using the private key, or by uploading the genesis ifle and the password relating to the account itself. At this point, the MetaMask wallet is ready to be used: Paolo can then manage his identity and examine the account balance and transactions before approving or rejecting them.
The functioning of the implemented system was finally tested and validated. The following figure shows an event corresponding to the expenditure of Ether following the deployment of the contract and therefore the creation of a new block. If the sensor detects a temperature of 26 degrees, i.e. a temperature higher than the maximum limit set by Paolo, the smart contract creates an event and subsequently a transaction which is stored within the blockchain. We have the correct functioning of the smart contract and of the system created in this work work.
The interaction between blockchain and IoT today represents an emerging technology given the vastness of the application fields to which it lends itself. From the tests conducted during the writing of this work it emerged that, in the smart home context, the use of a decentralized system capable of controlling the sensors positioned on electronic devices, such as the thermostat and the air conditioner, finds positive results in temperature management in a house. In the project it was fundamental to define a smart contract for the real-time control of temperature values: an alteration above or below a certain limit value set and decided by the owner of the "smart" house, determines the activation or deactivation of the air conditioning system without any manual intervention. The simplification and monitoring of connected devices is therefore evident. If from an application point of view the creation of the private Ethereum network in the LAN and the system connected to it has produced positive results, the reduction of energy costs and a better management of Paolo’s time and quality of private life, all that remains is set the physical connection of sensors as a future objective by setting up a Raspberry Pi3 as an interlocutor with the blockchain. 20–25