This is a shortened, less technical-oriented version of BitVMX’s site original published article.

Computation Paradigm

The Disputable Computation paradigm is an innovative way to handle disputes in blockchain computations. Initially introduced in 2017 by the TrueBit project, it gained traction for its low-cost arbitration capabilities and was later used in blockchain bridges and Optimistic Rollups for scaling solutions. BitVM, introduced in October 2023 by Robin Linus, applied this concept to Bitcoin. It ensures computation happens off-chain unless there's a dispute, minimizing blockchain usage. If disagreements arise, only the disputed portion is verified on-chain, making the process efficient and cost-effective.

BitVMX vs BitVM (Gate-Based)

The original gate-based BitVM protocol ("BitVM0") is largely theoretical and impractical for real-world applications like SNARK verification or sidechain interactions. In contrast, BitVMX and the BitVM CPU (BitVM1) are designed for practical use, offering significant improvements in efficiency and functionality.

BitVMX vs BitVM CPU

BitVMX improves on the BitVM CPU by simplifying and streamlining several processes:

• No Merkle Trees Needed: Unlike the BitVM CPU, BitVMX avoids complex Merkle tree setups for instructions and memory. Instead, it uses a straightforward sequential hash chain, significantly reducing setup and evaluation costs.
• Efficient Memory Handling: BitVMX tracks memory access faults through a new protocol, eliminating the need for memory merkelization.
• Broad CPU Compatibility: BitVMX supports a range of processors, from 8-bit to 64-bit, and can run Linux applications. This flexibility contrasts with BitVM CPU, which is tied to a single, non-standard CPU design.
• Optimized Search: BitVMX offers customizable search mechanisms for disputes, reducing transaction costs and challenge periods in many cases. For example, a 16-way search in BitVMX can cut the challenge period in half compared to BitVM CPU.

BitVMX vs BitVM2

While the BitVM CPU aims to run user-defined programs, BitVM2 specializes in running SNARK verifiers to validate complex computations. SNARKs offer advantages like privacy for inputs and consistent verification sizes, making them ideal for advanced use cases like sidechain withdrawal checks.

However, SNARKs also introduce complexity and risks due to potential bugs in the compilers and verifiers. BitVMX can also run SNARK verifiers, and the choice between BitVMX and BitVM2 depends on factors like transaction costs and round complexity. BitVM2 may require fewer rounds but comes with higher transaction costs.

Final Comparison

Both BitVMX and BitVM2 offer distinct advantages depending on the use case:

• Efficiency: BitVMX reduces setup and computational complexity, making it ideal for running various processors and applications efficiently.
• Advanced Applications: BitVM2 shines in scenarios requiring SNARK verifiers, particularly for private or recursive computations, despite its higher complexity and costs.

By leveraging these improvements, BitVMX establishes itself as a versatile and efficient solution for enhancing Bitcoin's computational capabilities.