BTLE: Atomic swaps with time-lock puzzles
We present BTLE (Broadcast Time-Lock Exchange Protocol), a two-step protocol that aims to decentralize exchange of funds between two blockchains in scenarios similar to online exchanges. BTLE leverages time-lock puzzles to achieve that. In the first phase, the BTLE-MA protocol allows for a matching...
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| Language: | English |
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De Gruyter
2025-04-01
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| Series: | Journal of Mathematical Cryptology |
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| Online Access: | https://doi.org/10.1515/jmc-2024-0044 |
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| author | Barbara Fadi Guglielmino Enrico Murru Nadir Schifanella Claudio |
| author_facet | Barbara Fadi Guglielmino Enrico Murru Nadir Schifanella Claudio |
| author_sort | Barbara Fadi |
| collection | DOAJ |
| description | We present BTLE (Broadcast Time-Lock Exchange Protocol), a two-step protocol that aims to decentralize exchange of funds between two blockchains in scenarios similar to online exchanges. BTLE leverages time-lock puzzles to achieve that. In the first phase, the BTLE-MA protocol allows for a matching between a market maker and one of the competing market takers. In the second phase, the BTLE-AS algorithm allows the exchange between the market maker and the winning market taker. It is not necessary to use both the BTLE-MA and BTLE-AS algorithms in a decentralized-exchange scenario: existing atomic swaps based on hashed time-lock contract (HTLC) can benefit from BTLE-MA and can be adapted to an exchange where there are multiple possible participants. Moreover, BTLE computations are off-chain, so BTLE can be used in those blockchain pairs where at least one of the two does not have a scripting language or where the pair do not have the same hash function in common. This solves a limitation of HTLC-based atomic swaps. We also propose a new time-lock puzzle based on Pell conic calculations as an alternative to the classical time-lock puzzle of Rivest et al. BTLE has been implemented and tested. Experiments demonstrate that this new time-lock puzzle based on the Pell conic is superior for the intended goal. With an NN-bit modulus of 2,000 bits, the RSW-TL approach resolves the puzzle in approximately 100 s, whereas our BM-TL method requires over 4,000 s, significantly reducing the number of squaring operations needed. |
| format | Article |
| id | doaj-art-d4ba09f7306e4c22b0dcc84c38e8468a |
| institution | DOAJ |
| issn | 1862-2984 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | De Gruyter |
| record_format | Article |
| series | Journal of Mathematical Cryptology |
| spelling | doaj-art-d4ba09f7306e4c22b0dcc84c38e8468a2025-08-20T03:18:37ZengDe GruyterJournal of Mathematical Cryptology1862-29842025-04-01191p. 28131010.1515/jmc-2024-0044BTLE: Atomic swaps with time-lock puzzlesBarbara Fadi0Guglielmino Enrico1Murru Nadir2Schifanella Claudio3Dipartimento di Informatica, Università di Torino, Via Pessinetto, 12, 10149, Torino (TO), ItalyDipartimento di Scienze Matematiche, Politecnico di Torino, Corso Duca degli Abruzzi, 24, 10129, Torino (TO), ItalyDipartimento di Matematica, Università di Trento, Via Sommarive 14, 38123, Povo (TN), ItalyDipartimento di Informatica, Università di Torino, Via Pessinetto, 12, 10149, Torino (TO), ItalyWe present BTLE (Broadcast Time-Lock Exchange Protocol), a two-step protocol that aims to decentralize exchange of funds between two blockchains in scenarios similar to online exchanges. BTLE leverages time-lock puzzles to achieve that. In the first phase, the BTLE-MA protocol allows for a matching between a market maker and one of the competing market takers. In the second phase, the BTLE-AS algorithm allows the exchange between the market maker and the winning market taker. It is not necessary to use both the BTLE-MA and BTLE-AS algorithms in a decentralized-exchange scenario: existing atomic swaps based on hashed time-lock contract (HTLC) can benefit from BTLE-MA and can be adapted to an exchange where there are multiple possible participants. Moreover, BTLE computations are off-chain, so BTLE can be used in those blockchain pairs where at least one of the two does not have a scripting language or where the pair do not have the same hash function in common. This solves a limitation of HTLC-based atomic swaps. We also propose a new time-lock puzzle based on Pell conic calculations as an alternative to the classical time-lock puzzle of Rivest et al. BTLE has been implemented and tested. Experiments demonstrate that this new time-lock puzzle based on the Pell conic is superior for the intended goal. With an NN-bit modulus of 2,000 bits, the RSW-TL approach resolves the puzzle in approximately 100 s, whereas our BM-TL method requires over 4,000 s, significantly reducing the number of squaring operations needed.https://doi.org/10.1515/jmc-2024-0044time lock puzzleblockchainatomic swapsdecentralized exchange11t71 |
| spellingShingle | Barbara Fadi Guglielmino Enrico Murru Nadir Schifanella Claudio BTLE: Atomic swaps with time-lock puzzles Journal of Mathematical Cryptology time lock puzzle blockchain atomic swaps decentralized exchange 11t71 |
| title | BTLE: Atomic swaps with time-lock puzzles |
| title_full | BTLE: Atomic swaps with time-lock puzzles |
| title_fullStr | BTLE: Atomic swaps with time-lock puzzles |
| title_full_unstemmed | BTLE: Atomic swaps with time-lock puzzles |
| title_short | BTLE: Atomic swaps with time-lock puzzles |
| title_sort | btle atomic swaps with time lock puzzles |
| topic | time lock puzzle blockchain atomic swaps decentralized exchange 11t71 |
| url | https://doi.org/10.1515/jmc-2024-0044 |
| work_keys_str_mv | AT barbarafadi btleatomicswapswithtimelockpuzzles AT guglielminoenrico btleatomicswapswithtimelockpuzzles AT murrunadir btleatomicswapswithtimelockpuzzles AT schifanellaclaudio btleatomicswapswithtimelockpuzzles |