Lelantos: The First Anonymous Blockchain-Based Delivery System
In the physical world, stores allow customers to maintain privacy by using cash, so they don’t have to reveal any personal information (such as name, address, etc.). In contrast, online marketplaces typically require buyers to provide all private data for billing and/or delivery. While cryptocurrencies like Bitcoin have revolutionized private billing through pseudonymous transactions, truly anonymous delivery of purchased goods remains an unsolved challenge.
A recently published article introduced a new blockchain-based system for delivering purchased goods called Lelantos. Experimental trials have shown that Lelantos offers users complete anonymity, fair exchange, and no direct links between sellers and buyers. The system is inspired by the routing approaches used in the Tor browser to ensure online anonymity. Additionally, Lelantos leverages blockchain decentralization to provide pseudonymous delivery of goods that is nearly impossible to trace. It also uses distributed consensus mechanisms and smart contracts to enforce fair, dispute-free transactions between trusted contractual parties.
Overview of Lelantos
Lelantos is a physical delivery system built on blockchain technology to preserve the anonymity of both sellers and buyers. The system implements a comprehensive routing approach through multiple companies. Lelantos consists of three main components:
- An interface that relies on locked smart contracts to facilitate the intermediate delivery process in a highly anonymous way, without the need for any intermediaries or third parties.
- A web service for advertising and registering potential delivery companies that can offer the requested service.
- Contract applications for monitoring the status and progress of smart contracts and interacting with them according to the role of each contractual party.
The creators of Lelantos defined the functional capabilities of the smart contract system and other cross-referenced elements, focusing on minimizing operations to reduce code execution and keep gas costs as low as possible. They also analyzed the security of the system’s core elements to ensure the required level of anonymity, fair exchange, privacy between buyers and sellers, and protection against unauthorized access. A working prototype of the Lelantos smart contract has been implemented as a proof of concept and is available as an open-source project on GitHub.
Key Features of the Anonymous Delivery System
The anonymous delivery system is designed based on a threat model that provides the following features:
- Fair Exchange: The anonymous package delivery system is moderated by a decentralized smart contract, ensuring fair transfer of funds to both sellers and delivery companies, and that the correct package is delivered to the intended customer.
- Buyer Anonymity: Customers do not need to disclose any personal information other than their pseudonym to any contractual party (i.e., sellers or delivery companies).
- Seller-Buyer Unlinkability: Any contractual party will know no more than two hops in the package’s delivery route, making it impossible to link the buyer to the seller.
How Lelantos Works
The smart contract used by Lelantos is an Ethereum-based contract written in Solidity. It allows customers to choose the route their package will take through a group of delivery companies of their choice. For each selected delivery company, the customer prepares an encoded message that includes the tracking number and the address of the next delivery company, hidden by another number. All transmitted text is encrypted via the smart contract, so tracking numbers are only meaningful to the customer. In other words, all information about the package’s delivery route and the number of delivery companies involved is hidden from everyone except the customer and each pair of consecutive delivery companies.
With the recent rise in Ethereum prices, gas costs have also increased. Executing a smart contract on the Ethereum blockchain requires payment for computational resources throughout the process, paid in Ether gas.
To date, Lelantos is the first attempt to provide an anonymous, blockchain-based package delivery system.
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