Tempora-Fusion: Time-Lock Puzzle with Efficient Verifiable Homomorphic Linear Combination
This addresses a limitation in homomorphic TLPs for applications like federated learning and e-voting, though it appears incremental as it builds on existing TLP variants.
The paper tackles the problem of verifying computation correctness in homomorphic time-lock puzzles, which are used for secure future information transmission, by introducing Tempora-Fusion, a scheme that enables verifiable homomorphic linear combinations without asymmetric-key cryptography, achieving efficient implementations.
To securely transmit sensitive information into the future, Time-Lock Puzzles (TLPs) have been developed. Their applications include scheduled payments, timed commitments, e-voting, and sealed-bid auctions. Homomorphic TLP is a key variant of TLP that enables computation on puzzles from different clients. This allows a solver/server to tackle only a single puzzle encoding the computation's result. However, existing homomorphic TLPs lack support for verifying the correctness of the computation results. We address this limitation by introducing Tempora-Fusion, a TLP that allows a server to perform homomorphic linear combinations of puzzles from different clients while ensuring verification of computation correctness. This scheme avoids asymmetric-key cryptography for verification, thus paving the way for efficient implementations. We discuss our scheme's application in various domains, such as federated learning, scheduled payments in online banking, and e-voting.