New Soft Fork Proposal Could Make Bitcoin More Programmable

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The CTV and CSFS soft fork proposes adding two new opcodes to Bitcoin: OP_CHECKTEMPLATEVERIFY (CTV) and OP_CHECKSIGFROMSTACK (CSFS). These would allow more programmable and efficient spending rules, improving tools like Lightning, vaults, and dApps. Supporters see gains in cost, speed, and privacy, while critics call for wider consensus and question the trade-offs.

Bitcoin hasn’t seen an update at the consensus level since the Taproot soft fork in 2021. There have been discussions around conceptual proposals from time to time; however, none of them garnered much support. At least, not until a letter was published from a variety of Bitcoin developers that indicated the signers’ collective support for a soft fork for the eventual activation of two new opcodes on the network: OP_CHECKTEMPLATEVERIFY (CTV) and OP_CHECKSIGFROMSTACK (CSFS).

Since then, additional signers have come on board, and at least some contributors to Bitcoin Core, which is the full node implementation used by the vast majority of the network, consider the subject worthy of discussion. There is still a long path forward for activation of these new ways of programming Bitcoin transactions, but this is the most momentum a soft fork has had since Taproot’s ultimate success.

Let’s look at the details of CTV and CSFS to figure out what they could mean for Bitcoin and whether activation could be coming soon. There is definitely plenty of excitement around proposed use cases for these opcodes, but there are also some Bitcoin users who are hesitant to move forward too quickly.

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What are OP_CHECKTEMPLATEVERIFY and OP_CHECKSIGFROMSTACK?

CTV and CSFS are two opcodes related to covenants, which are basically a way to restrict how some bitcoin can be spent in the future. While Bitcoin is currently mostly concerned with who can spend some bitcoin, covenants add another condition in terms of how some bitcoin can be spent. For example, some bitcoin could be restricted in terms of which specific Bitcoin addresses it can be sent to in the future.

From a technical standpoint, both CTV and CSFS involve checking the cryptographic signature on some text. CSFS can be seen as more general than CTV because CSFS checks the signature on any arbitrary message while CTV can only check a signature on a specific Bitcoin transaction template. In fact, the functionality enabled by CTV could be implemented with CSFS, albeit in a more complex and less efficient manner.

What benefits would CTV and CSFS bring to Bitcoin?

Many of the benefits related to the combined introduction of CTV and CSFS to Bitcoin Script via a soft fork are focused on improving the quality of various layer-two networks that are intended to scale the use of bitcoin to many more users while retaining aspects of what makes the cryptocurrency useful and valuable in the first place such as decentralization, self custody, privacy, security, programmability, and more. Additionally, there are some security and functionality benefits to be had for transactions that continue to take place at the base blockchain layer.

In terms of specific off-chain Bitcoin protocols that can be helped with CTV and/or CSFS, the list includes: the Lightning Network, Ark, Statechains, various types of sidechains, and more. While the specific technical enhancements enabled by CTV and CSFS for these systems can get a bit complicated, the resulting benefits for users include faster and cheaper transactions, fewer on-chain interactions, stronger protections against censorship or trusted intermediaries failing on upper layer protocols, and improvements for user interfaces.

Notably, many of the developers working on these off-chain transaction protocols are supporters of soft-forking CTV and CSFS into Bitcoin.

In terms of use on the Bitcoin base layer, vaults are an often-touted use case of covenants where CTV is said to be useful. Much like the various off-chain transaction protocols for additional bitcoin transaction layers, vaults are possible today; however, many of those working on services related to secure bitcoin custody, such as Casa co-founder and Chief Security Officer Jameson Lopp, argue that they can see massive enhancements through the use of covenants.

Additionally, there are other miscellaneous use cases of CTV and CSFS such as improvements for discreet log contracts (DLCs) that are used in decentralized betting applications. Of course, this is not an exhaustive list of all the different use cases that are enabled by CTV and CSFS, and there may also be additional benefits that are not found until developers are able to play around with these opcodes on Bitcoin’s mainnet.

What are the arguments against this soft fork?

In terms of activating this soft fork right now, there is simply not enough obvious support from Bitcoin users quite yet. Developers working on off-chain transaction protocols, vaults, and some other systems are interested in this soft fork, but public support from miners and economic nodes is less clear. In other words, the people using Bitcoin need to be convinced that this is a worthwhile upgrade before it can happen.

General lack of attention and interest to the matter from users is one thing, but there are also specific reasons some detractors have given for not wanting to see this soft fork activate on Bitcoin anytime soon.

Some users think this soft fork does not help enough and a more powerful change would be better. There are a variety of covenants proposals out there that could enhance developer expressivity even further than CTV and CSFS, and there are also complete revamps of Bitcoin’s scripting language from the ground up, such as Simplicity, which Blockstream CEO Adam Back has referred to as potentially the “last soft fork” Bitcoin could ever need.

On the other end of the spectrum, there are those who say CTV and CSFS go too far or are simply not needed. These detractors say much of what CTV and CSFS enable is already possible on Bitcoin today through the use of pre-signed transactions and the supposed improvements are simply not worth the risk tradeoffs involved in soft fork coordination. They also say some use cases need to be proved out and tested before Bitcoin’s consensus rules should be changed to support them.

Additionally, there are concerns around covenants due to their potential to enable MEVil, perverse incentives, and new attack vectors. New, unknown use cases of CTV and CSFS that are invented by developers once it is live on mainnet were previously mentioned as a benefit, but there is also sometimes trouble in the unknown unknowns. Bitcoin is not a system known to introduce unknown risks that could alter the game theory that incentivizes users to act a certain way and holds the whole system together in the first place.

CTV & CSFS could quietly redefine Bitcoin’s capabilities

As a financial analyst closely following protocol-level developments in Bitcoin, I view the CTV and CSFS soft fork proposal as a quiet but foundational shift — one that won’t immediately capture headlines, but could ultimately shape Bitcoin’s next decade.

We’re not just talking about optimization; we’re talking about evolution. Bitcoin’s ability to support complex custody setups, non-custodial payment channels, and more expressive off-chain interactions has long been limited by the rigidity of its scripting language. CTV and CSFS offer an incremental, pragmatic way to unlock that next layer of functionality — without overhauling Bitcoin’s core principles.

But here’s the reality: adoption won’t be decided by technical merit alone. It will hinge on economic utility. Once wallets, institutions, or sovereign-grade custodians begin leveraging CTV-powered vaults or CSFS-enabled protocols to secure billions in assets with fewer trust assumptions, the tide of consensus will turn faster than most expect.

I anticipate a slow build in 2025: more developer experimentation, a handful of testnet demos, and increasing calls from infrastructure players for activation readiness. If that momentum holds, we could realistically see a community-wide push for inclusion in a future soft fork window by late 2026 or early 2027.

That said, Bitcoin's ethos demands caution — and rightly so. But the greater risk, in my view, is stagnation. Without safe, targeted upgrades like CTV and CSFS, Bitcoin risks losing ground to more programmable chains in areas like secure automation, cross-chain protocols, and custody innovation.

The future of Bitcoin programmability is not about competing with Ethereum — it’s about hardening Bitcoin’s unique value through minimal, deliberate tools. And this proposal is a step in exactly that direction.

Conclusion

The proposal to soft fork CTV and CSFS into Bitcoin represents a meaningful step toward improving the network’s programmability, scalability, and security. While the momentum behind this proposal is stronger than we’ve seen since Taproot, activation will require broad consensus not just from developers, but from miners, businesses, and everyday users. As with any change to Bitcoin’s consensus rules, the stakes are high and caution is warranted. The road ahead will likely involve more technical reviews, testing, education, and community discussion.

Time will tell in terms of whether the economic nodes on Bitcoin think the risks associated with this change are worth it. While there is some element of risk associated with any soft fork, there is also a risk of Bitcoin not being able to scale in a manner that retains its underlying value proposition without this sort of improvement.

FAQs

What is a soft fork?

In Bitcoin, a soft fork is a backwards compatible change, where old, non-upgraded nodes don’t need to know about the new rules being enforced.

What is a Bitcoin opcode?

An opcode is a command in Bitcoin’s programming language that allows node software to verify that a transaction is valid based on a specific set of instructions.

What is CTV?

The CTV opcode is intended to do just what it says: check a predefined template for how a transaction can be spent before it can be spent. That template includes information such as the number of inputs and outputs, the full data of the outputs, and the nLockTime of the transaction.

What is CSFS?

CSFS expands the types of cryptographic signatures that can be verified by the Bitcoin network. OP_CHECKSIG already exists to check that a signature on a transaction is valid, but CSFS expands this to check any arbitrary message.

Team that worked on the article

Kyle began exploring Bitcoin in 2013, when public interest in cryptocurrencies was just beginning to grow. At first, it was more of a hobby. He wrote articles and reviews while studying both the market and the underlying technology. However, his enthusiasm quickly evolved into a professional pursuit: by early 2014, Kyle became Editor-in-Chief at Crypto Coins News.

Between 2015 and 2017, he actively reported on the major debate within the Bitcoin community over block size, often called the "block size war." The controversy centered on whether to increase Bitcoin’s block limit to improve network scalability.

During this period, Kyle also served multiple terms as Editor-in-Chief at Inside Bitcoins, another leading digital currency news outlet.

Over time, his name became widely recognized. His work has appeared in top-tier publications including CoinDesk, Business Insider, Wired UK, and Fortune. Thanks to the consistent quality of his reporting and thoughtful analysis, he earned a reputation as one of the most trusted voices in crypto journalism. Kyle has also found success on Twitter, where he has built a large and engaged following.

”The root problem with conventional currency is all the trust that's required to make it work. The central bank must be trusted not to debase the currency, but the history of fiat currencies is full of breaches of that trust. Banks must be trusted to hold our money and transfer it electronically, but they lend it out in waves of credit bubbles with barely a fraction in reserve. We have to trust them with our privacy, trust them not to let identity thieves drain our accounts. Their massive overhead costs make micropayments impossible.” - Satoshi Nakamoto

Since 2025, Kyle has expanded his professional scope by becoming a contributing writer for Traders Union. This role allows him to deepen his engagement with traditional finance while maintaining a strong focus on cryptocurrency and blockchain.

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Chinmay Soni is a financial analyst with more than 5 years of experience in working with stocks, Forex, derivatives, and other assets. As a founder of a boutique research firm and an active researcher, he covers various industries and fields, providing insights backed by statistical data. He is also an educator in the field of finance and technology.

As an author for Traders Union, he contributes his deep analytical insights on various topics, taking into account various aspects.

Mirjan Hipolito is a journalist and news editor at Traders Union. She is an expert crypto writer with five years of experience in the financial markets. Her specialties are daily market news, price predictions, and Initial Coin Offerings (ICO).

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