BitVMX: A CPU for Universal Computation on Bitcoin
Sergio Demian Lerner, Ramon Amela, Shreemoy Mishra, Martin Jonas,, Javier \'Alvarez Cid-Fuentes

TL;DR
BitVMX introduces a flexible virtual CPU design for Bitcoin that enables arbitrary program execution using hash chains, challenge-response protocols, and authenticated communication, improving verification efficiency over previous methods.
Contribution
It presents a novel CPU design supporting architectures like RISC-V, utilizing hash chains and a new challenge-response protocol to verify arbitrary computations on Bitcoin.
Findings
Supports common architectures like RISC-V and MIPS
Avoids complexities of Merkle trees and signature equivocations
Flexible instantiation balancing cost and complexity
Abstract
BitVMX is a new design for a virtual CPU to optimistically execute arbitrary programs on Bitcoin based on a challenge response game introduced in BitVM. Similar to BitVM1 we create a general-purpose CPU to be verified in Bitcoin script. Our design supports common architectures, such as RISC-V or MIPS. Our main contribution to the state of the art is a design that uses hash chains of program traces, memory mapped registers, and a new challenge-response protocol. We present a new message linking protocol as a means to allow authenticated communication between the participants. This protocol emulates stateful smart contracts by sharing state between transactions. This provides a basis for our verification game which uses a graph of pre-signed transactions to support challenge-response interactions. In case of a dispute, the hash chain of program trace is used with selective pre-signed…
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Taxonomy
TopicsCloud Computing and Resource Management · Blockchain Technology Applications and Security
