Bitcoin has improved significantly since the release of its whitepaper in 2009. These improvements have been aimed at bolstering network features such as scalability, security, and efficiency. Among these improvements is a proposed soft fork called CheckTemplateVerify (CTV), which is specified under the Bitcoin Improvement Proposal 119 (BIP 119) by Jeremy Lubin. BIP 119 introduces the concept of OP_CheckTemplateVerify, or OP_CTV in short, which aims to improve the management and security of Bitcoin transactions.

Read on as we explore the CTV opcode and its potential to enhance the deployment of financial applications on the Bitcoin network.

What Is the CheckTemplateVerify Proposal? 

CheckTemplateVerify (CTV) is a proposal to improve Bitcoin’s functionality through a soft fork. This allows upgrading the network and ensures compatibility for nodes that opt not to update as long as a majority of hash power enforces the new rules.

CTV introduces the ability for a user to limit where they can spend specific bitcoin. This goes beyond conventional ownership via private keys or timelocks.

In a pre-CTV world, time locks help restrict the spending of a transaction until a specified time when a particular block height has been achieved. In this scenario, it means restrictions are in place on when the funds will be used. However, there are no specific guidelines about how and where the funds will be spent.

The CTV template proposes that network participants have the capability to control the possible ways that funds will be used through Bitcoin covenants. Covenants are transactions that impose restrictions on future Bitcoin spending, offering users more control and flexibility over their funds.

CTV’s design and use cases were detailed in Bitcoin Improvement Proposal (BIP) 119, authored by Jeremy Rubin.

How Would BIP-119 Enhance Financial Applications on Bitcoin?

BIP-119, facilitated by CTV, brings advancements in Bitcoin’s financial applications. Some of the enhancements include security, transaction efficiency, and scalability. 

Vaults For Secure Storage

CTV enables the creation of vaults, similar to digital safes, where users can securely store their Bitcoin. Vaults can impose specific spending conditions, such as withdrawal limits and time constraints, adding an extra layer of protection against unauthorized access. For instance, users can set withdrawal limits on their wallets to mitigate potential loss in the event of a security breach.

Enhanced Security Features

CTV improves security measures within financial applications by allowing the creation of transactions with predefined conditions. Funds stored in a vault may require additional authorization or be subject to time locks, reducing the risk of immediate theft even if private keys are compromised.

Streamlined Operations on Layer 2 Solutions

CTV allows the development of novel layer 2 protocols that can operate alongside existing solutions like the Lightning Network. These solutions can leverage CTV’s features to enhance transaction efficiency, security, and versatility.

Congestion Control

CTV enables congestion control mechanisms by allowing large-volume payment processors to aggregate multiple transactions into a single, efficient transaction. This reduces the demand for block space during periods of high congestion, optimizing transaction processing and minimizing user costs.

Improvements to the Lightning Network

CTV enhances the scalability of the Lightning Network by enabling the creation of more efficient payment channels. With CTV, less data is required to create Hashed Time Locked Contracts (HTLCs), allowing for a higher maximum number of HTLCs per channel. This improves the scalability and usability of the Lightning Network, facilitating smoother and more cost-effective microtransactions.

Reasons For and Against the CTV Opcode Proposal

BIP-119 has triggered debates and divisions within the Bitcoin community. While opinions vary, proponents and opponents offer different perspectives on the proposal’s potential impact.


Enhanced Security

CTV introduces Bitcoin vaults, which offer users a highly secure method for storing their Bitcoin. Unlike traditional wallets, Bitcoin vaults can enforce specific spending conditions, introducing an additional layer of security to users’ holdings. Even if hackers gain unauthorized access to private keys, they cannot immediately transfer the Bitcoin.

Enhanced Functionality

Supporters argue that CTV introduces a range of new capabilities to Taproot-enabled wallets, specifically vaults and covenants. These features provide spending conditions that can restrict how and where authorized users spend their Bitcoin. In addition, CTV allows for a range of new layer 2 solutions to come up and create more secure, efficient, and user-friendly platforms. 


CTV allows the creation of payment conditions where multiple parties share the same Unspent Transaction Outputs (UTXOs). This feature consolidates transactions into single UTXOs, with enforced spending restrictions. Payment pools, facilitated by CTV, have implications for exchanges, mining pools, and coinjoin services, potentially improving transaction efficiency and scalability.


Despite its potential benefits, here are some reasons against the proposal:

Bitcoin’s Fungibility Issue

BIP-119 could undermine Bitcoin’s fungibility, a fundamental characteristic of the cryptocurrency. Bitcoin’s fungibility relies on the uniformity of each Bitcoin unit, ensuring that the coins are interchangeable and indistinguishable from one another. 

Introducing covenants that modify the properties of some Bitcoin could create distinctions among them, affecting their fungibility. Bitcoin, subject to covenants, might be perceived as less valuable due to restricted usage options. Additionally, distinctive features could compromise privacy and censorship resistance on the network.

Additional Complexity

Implementing BIP-119 could introduce unnecessary complexity into the Bitcoin protocol, posing risks to its security and robustness. Adding a new opcode increases the attack surface, which could expose the network to further vulnerabilities. 

Moreover, BIP-119 may lead to unforeseen scenarios. Complex conditions may cause verification issues and potentially loss of funds when users fail to meet the requirements. As a result, Bitcoin held in the covenant may be locked indefinitely. Meanwhile, covenants could create infinite loops by referring to themselves or others in a circular chain of transactions, consuming network resources and causing scalability issues. 

Final Word

BIP-119’s OP_CTV introduces a range of functionalities to revolutionize Bitcoin transactions and enhance security, scalability, and efficiency.

CTV’s potential lies in its capacity to introduce more complex transaction types while preserving Bitcoin’s simplicity and security. Features like Bitcoin vaults and shared UTXOs improve Bitcoin’s utility and user experience.

While the proposal has received considerable support, concerns about the added complexity and potential risks to the network’s security need to be addressed before implementation becomes possible.