An Offline Delegatable Cryptocurrency System

TL;DR

DelegaCoin is a secure offline delegatable cryptocurrency system that uses trusted execution environments to prevent double-spending and malicious delegation without relying on a third-party or blockchain interaction.

Contribution

It introduces a novel offline delegation scheme utilizing TEEs to enhance security and decentralization in cryptocurrency transactions.

Findings

Scheme is provably secure against double-spending.

Prototype demonstrates practical feasibility.

Achieves offline delegation without blockchain interaction.

Abstract

Blockchain-based cryptocurrencies, facilitating the convenience of payment by providing a decentralized online solution, have not been widely adopted so far due to slow confirmation of transactions. Offline delegation offers an efficient way to exchange coins. However, in such an approach, the coins that have been delegated confront the risk of being spent twice since the delegator's behaviour cannot be restricted easily on account of the absence of effective supervision. Even if a third party can be regarded as a judge between the delegator and delegatee to secure transactions, she still faces the threat of being compromised or providing misleading assure. Moreover, the approach equipped with a third party contradicts the real intention of decentralized cryptocurrency systems. In this paper, we propose \textit{DelegaCoin}, an offline delegatable cryptocurrency system to mitigate such an issue. We exploit trusted execution environments (TEEs) as decentralized "virtual agents" to prevent malicious delegation. In DelegaCoin, an owner can delegate his coins through offline-transactions without interacting with the blockchain network. A formal model and analysis, prototype implementation, and further evaluation demonstrate that our scheme is provably secure and practically feasible.