Bitcoin needs this OP code more than OP_CAT Bitcoin needs this OP code more than OP_CAT

Bitcoin needs this OP code more than OP_CAT

Integrating zero-knowledge proofs would enhance Bitcoin's privacy, scalability, and utility.

Bitcoin needs this OP code more than OP_CAT

Cover art/illustration via CryptoSlate. Image includes combined content which may include AI-generated content.

Bitcoin’s blockchain technology has long been hailed for its decentralized nature and robust security, making it a cornerstone in the digital asset space. While Bitcoin’s primary role as a cryptocurrency is well-established, its potential as a decentralized timestamping server and global event sequencer opens up new avenues for innovation.

As I often say when talking to developers, while I once ran a development house and can code in several languages myself, I still consider myself an enthusiastic amateur and know ‘enough to be dangerous.’ I welcome any constructive criticism of this op-ed, which is based on my recent essay, ‘How Bitcoin can save the world.


Before explaining why we should view Bitcoin as a global timestamping server and event sequencer, it’s crucial to consider the necessary advancements to enhance its functionality. To realize Bitcoin’s potential beyond “perfect money,” we either need to overhaul Bitcoin or allow it to interact betterย with other layers. I don’t believe the first option is prudent, but one small update could be all it needs.

At BTC Prague, Charles Guillemet introduced me to an idea I’d never considered: introducing new operation codes (OP_CODES) dedicated to enabling zero-knowledge proofs (ZKPs) on Bitcoin. Currently, there is much debate about bringing back the OP_CAT opcode, which facilitates data concatenation. After my chat with Charles, I believe this is less critical to Bitcoin’s future than an OP_CODE similar to the proposed OP_ZKP.

Bitcoin’s blockchain provides a trustless method for recording and verifying the sequence of events and the timestamps of digital assets. In traditional systems, establishing the existence and integrity of data at a specific point in time relies on centralized authorities, which can be manipulated or compromised. Bitcoin’s decentralized nature and cryptographic security offer a robust alternative, ensuring tamper-proof records of data existence. This capability has profound implications for intellectual property protection, contract execution, and supply chain transparency. The community needs to ensure these upgrades do not compromise Bitcoin’s fundamental principles.

The current limitations of Bitcoin’s scalability and data storage capacity can be mitigated through Layer 2 solutions like the Lightning Network, sidechains, or meta-layers, as well as interoperability projects such as ICP’s Bitcoin canisters. These solutions enhance Bitcoin’s throughput by processing transactions off-chain and only settling the final balances on the main blockchain. However, privacy concerns and complete state verification remain a significant barrier. Bitcoin’s transparency is beneficial for verifiability but problematic for applications requiring confidentiality, such as medical records and financial transactions. Furthermore, while it is currently possible to hash data into Bitcoin to validate off-chain data, it is missing the extended functionality that ZK-rollups would bring, reducing the trust required of meta-layers.

Zero-knowledge proofs and Bitcoin

This is where zero-knowledge proofs and roll-ups come into play. ZKPs allow one party to prove the validity of a statement without revealing the underlying data, thus ensuring privacy without sacrificing security. Integrating ZKPs into Bitcoin’s protocol through dedicated OP_CODES, such as OP_ZKP, would enable private, verifiable transactions. This innovation is crucial for applications that require confidentiality and could significantly enhance Bitcoin’s utility and adoption.

In contrast, the OP_CAT opcode, which allows for concatenating data elements within Bitcoin’s scripting language, is less transformative. While OP_CAT could facilitate the verification of ZK-proofs on Bitcoin, it does not directly address the fundamental challenges of scalability and privacy. The Bitcoin community has historically been cautious about adding new opcodes due to potential security risks. The reintroduction of OP_CAT, removed previously for security concerns, must be carefully weighed against the broader benefits of introducing ZKP-enabling opcodes.

Recent proposals highlight the promise of ZKP integration. The ZeroSync Association, for example, is developing tools to enable succinct ZK-proofs on Bitcoin, potentially validating the state of the Bitcoin network without requiring users to download the entire blockchain. This development could streamline blockchain verification and enhance the network’s efficiency. Similarly, projects like Chainway and Kasar Labs are working on integrating ZK-Rollups with Bitcoin, which would batch multiple transactions into a single proof, improving scalability and reducing costs. Also, last year, Weiji made a proposal for OP_ZKP via a soft fork,

“This new opcode OP_ZKP will enable the Bitcoin network to authorize spending based on off-chain computation, provided acceptable proof is supplied.

This will not only equip the Bitcoin script with Turing completeness, but also enable the building of payment channels more flexible, stablecoin, decentralized exchange, DeFi, etc. directly over the Bitcoin network, or even a layer 2.”

However, the complexity of implementing ZKPs on Bitcoin cannot be understated. Changes to the protocol and broad consensus within the community are required. Generating and verifying ZKPs is computationally intensive, necessitating optimization to ensure efficient use on the network. Moreover, achieving widespread adoption of ZKPs and new OP_CODES will require convincing the conservative Bitcoin community of their benefits and security.

In conclusion, while the OP_CAT opcode offers some utility, introducing dedicated OP_CODES for zero-knowledge proofs is far more critical to Bitcoin’s evolution. ZKPs provide a path forward for enhancing privacy, scalability, and functionality, making Bitcoin a more versatile and secure platform for many applications.

As the Bitcoin network continues to develop, focusing on integrating ZKPs will unlock new potentials and solidify its role as a foundational technology in the digital economy. Therefore, the Bitcoin community should prioritize these advancements over the reintroduction of OP_CAT, ensuring that Bitcoin remains at the forefront of innovation in the blockchain space.

Mentioned in this article