Emulating OP_RAND

Paul Gerhart, a PhD student at TU Wien, has recently focused his research on enhancing blockchain technology, specifically within the realms of atomic swaps and payment channels. His work has contributed to the development of adaptor signatures and fair exchange protocols, as evidenced by his publications listed in cryptographic archives (ia.cr/2024/1809, ia.cr/2025/388, and ia.cr/2026/395). Alongside colleagues Jay and Aravind, Gerhart has introduced an innovative concept known as probabilistic swaps. This new mechanism operates similarly to traditional atomic swaps but incorporates a fixed, publicly verifiable probability into one party’s transfer execution.

In their recent paper, available on arXiv (Probabilistic Swaps on Blockchain Networks), they describe how probabilistic swaps leverage the evaluation of oblivious pseudorandom functions (OPRFs) to facilitate randomized outcomes in transactions without requiring trust between parties. This method notably enhances efficiency by minimizing the computational burden on participants; only the dealer is required to send a zero-knowledge proof (NIZK).

Gerhart details two distinct implementations of the well-formedness proof supporting this technology. The first implementation utilizes Bulletproofs to maintain nearly constant proving times across different winning probabilities. Alternatively, the second approach employs a cut-and-choose method that does not rely on the random oracle model, offering greater efficiency for higher winning probabilities (above 2^{-12}). These advancements suggest significant practical value, as demonstrated by successful deployments on the Bitcoin testnet and within the Lightning Network.

This research not only aligns with but also builds upon existing proposals like OP_RAND to enable trustless randomized outcomes on platforms such as Bitcoin, representing a noteworthy step forward in the quest for more versatile and secure blockchain interactions.