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

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.