# Interledger Smart Contracts for Decentralized Authorization to Constrained Things

## TL;DR

This paper introduces models using smart contracts and interledger mechanisms to enable decentralized authorization for constrained IoT devices, balancing cost, delay, complexity, and privacy.

## Contribution

It proposes novel models leveraging multiple blockchains and interledger protocols for decentralized IoT authorization, with evaluations on Ethereum testnets.

## Key findings

- Recorded hashes of authorization info in smart contracts for immutability
- Achieved resilience through smart contract execution on multiple nodes
- Reduced data transmission to constrained IoT devices

## Abstract

We present models that utilize smart contracts and interledger mechanisms to provide decentralized authorization for constrained IoT devices. The models involve different tradeoffs in terms of cost, delay, complexity, and privacy, while exploiting key advantages of smart contracts and multiple blockchains that communicate with interledger mechanisms. These include immutably recording hashes of authorization information and policies in smart contracts, resilience through the execution of smart contract code on all blockchain nodes, and cryptographically linking transactions and IoT events recorded on different blockchains using hash and time-lock mechanisms. The proposed models are evaluated on the public Ethereum testnets Rinkeby and Ropsten, in terms of execution cost (gas), delay, and reduction of data that needs to be sent to the constrained IoT devices.