Multi-party fair exchange protocol

In cryptography, a multi-party fair exchange protocol is protocol where parties accept to deliver an item if and only if they receive an item in return.[1]

Definition

Matthew K. Franklin and Gene Tsudik suggested in 1998[2] the following classification:

• An ${\displaystyle n}$-party single-unit general exchange is a permutation ${\displaystyle \sigma }$ on ${\displaystyle \{1...n\}}$, where each party ${\displaystyle P_{i}}$ offers a single unit of commodity ${\displaystyle K_{i}}$ to ${\displaystyle P_{\sigma (i)}}$, and receives a single unit of commodity ${\displaystyle K_{\sigma ^{-1}(i)}}$ from ${\displaystyle P_{\sigma ^{-1}(i)}}$.
• An ${\displaystyle n}$-party multi-unit general exchange is a matrix of baskets, where the entry ${\displaystyle B_{ij}}$ in row ${\displaystyle i}$ and column ${\displaystyle j}$ is the basket of goods given by ${\displaystyle P_{i}}$ to ${\displaystyle P_{j}}$.

See also

Secure multi-party computation

References

1. Mukhamedov, Aybek; Kremer, Steve; Ritter, Eike. "Analysis of a Multi-Party Fair Exchange Protocol and Formal Proof of Correctness in the Strand Space model". Financial Crypto. 2005.
2. Franklin, Matthew K.; Tsudik, Gene (1998). "Secure Group Barter: Multi-party Fair Exchange with Semi-trusted Neutral Parties". Lecture Notes in Computer Science. 1465: 90–102. doi:10.1007/BFb0055475. ISBN 978-3-540-64951-9.