This contract is an example of how to use a Blockduino board and the Blockduino SDK to execute a function and receive a payment for successfully performing it. It shows how to make available to an Ethereum contract the paid services of a TrueRNG Pro device connected to the Blockduino USB serial connection.
The contract is deployed providing the adress of the core Blockduino contract and the address of the Blockduino board Ethereum account. That is the board used to generate random numbers from the TrueRNG device.
To obtain a true random number generated from Blockduino, a transaction is sent to the generate() function of this contract with a value of 0.02 Ether. The fee paid minus the gas needed for the transaction to the board, is transfered to the Blockduino Ethereum account used by the contract, and the random number generated is copied in the randomNumber global public variable of the contract.
For the
randomNumberglobal public variable to receive a new value, two transactions must be mined by the blockchain, one with the request and one with the response.
After the request is sent to the Blockduino board and the transaction is mined, the Blockduino will reply sending a second transaction to the Blockduino core contract with the response. Once the response transaction is mined the Blockduino core contract will then invoke the callback function in the the Randomizer contract with the random number as a bytes32 variable.
The fee received for obtaining a random number can be changed modifying the
RNF_FEEconstant.
The TrueRNG device generates a stream of full-entropy bit-strings that is readable through the USB serial port.
As of Q3 2018 the Blockduino board is still under development and not yet available. Software to emulate functions of the Blockduino board, and to use the Blockduino SDK on a Raspberry PI, is available in the Blockduino Raspberry PI repo.
A Blockduino core contract is deployed on the Ropsten testnet at the address:
0xc859b2826d7c39a5cca1f651c053523b45aba64f
In its final version, the Blockduino board will provide remote attestation with every response to a request. With remote attestation, a Blockduino device authenticates its hardware and software configuration to a remote host. The goal of remote attestation is to enable the contract sending the request to determine the level of trust in the integrity of the platform running on the Blockduino device.
This feature is not available for the Raspberry PI hardware or for any hardware that does not provide a Trusted Execution Environment.