If For example Entity A wants to build a smart contract that manage a group of devices. But since each device uses pseudonym and he may change it later, is there any way to build the contract such that each device should have a certain address for a certain amount of Time ( month for example) and Is it available now in Etherum so that that Entity A can issue addresses for devices joining the smart contract ? Just thinking of a private application on the etherum controlled by a single entity and also also he would like to detect bad users

1 Answer 1


It would be better for the devices to have semi-permanent identifiers, their address, and then Entity A will have exclusive management control of a whitelist or similar access control system. The contract would reject interactions from unauthorized devices.

This is just a very quick sketch with some important concerns glossed over to illustrate the idea.

pragma solidity 0.4.25;

contract SimpleWhitelist {

    address public owner;
    mapping(address => bool) public isAuthorizedDevice;

    modifier onlyOwner {

    modifier onlyAuthorizedDevice {

    constructor() public {
        owner = msg.sender;

    function addOrRemoveDevice(address device, bool authorized) public onlyOwner {

    function somethingDevicesDo() public onlyAuthorizedDevice {
        // contract rejects transaction unless the sender is whitelisted.

Hope it helps.

  • But this solution require a previous knowledge from Entity A about the white list. This may endanger their privacy /anonymity since Entity A can link future transactions with one of them
    – Mohamed
    Commented Oct 17, 2018 at 15:14
  • I think we need to know more about the secrecy requirements and frequency of transactions, scale, etc., to know if your plan is feasible. Commented Oct 17, 2018 at 15:31
  • The idea is at some time slot,Entity A will receive requests from some other devices and based on this information , each device will be assigned some value . So the following security/ privacy are required: 1. Keeping privacy of users identities from Entity A 2. Also Entity A would like to detect if one of the devices misbehaved by trying to change his request in future to gain more privileges.
    – Mohamed
    Commented Oct 17, 2018 at 15:48

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