- CSFS increases script signature flexibility; combines with CTV for more robust Lightning Network channels and mining tools.
- Signers cite 5/8 year maturity of CTV/CSFS proposals, arguing their moderate impact warrants Core integration review now.
A group of Bitcoin developers, miners, and company representatives sent an open letter on June 9th. They asked the Bitcoin Core development team to review two specific transaction features. These features are known as OP_CHECKTEMPLATEVERIFY (CTV) and OP_CHECKSIGFROMSTACK (CSFS). More than 40 people signed the request, including James O’Beirne, Jameson Lopp, and representatives from mining pools like f2pool and Luxor.
The letter, hosted on ctv-csfs.com, asks Bitcoin Core contributors to prioritize integrating CTV (BIP-119) and CSFS (BIP-348) into the software within six months. This integration would be a first step. It does not demand immediate activation via a soft fork.
Instead, it aims to include the code in Bitcoin Core, allowing the broader community to later decide on activation. The signers see this as necessary to move past delays in adopting technical improvements they believe Bitcoin needs.
CTV and CSFS are types of transaction rules, often called opcodes. CTV allows users to set a pre-defined path for spending bitcoins. This ensures funds can only move in one specific way agreed upon beforehand.
For example, it helps create secure vaults protecting against theft or enables complex financial agreements known as Discreet Log Contracts (DLCs). CSFS provides more flexibility in how Bitcoin scripts verify cryptographic signatures. Used together, these features could make the Lightning Network more robust and efficient. They could also simplify systems for non-custodial Bitcoin mining.
- Enables New Security Tools: CTV allows creating vaults where stolen funds can be recovered and ensures funds are only spent in pre-agreed ways (like complex financial contracts/DLCs), directly improving user asset protection.
- Increases Transaction Flexibility: CSFS allows more complex signature verification within Bitcoin scripts, enabling new types of conditional payments and agreements that weren’t possible or were harder to implement securely before.
- Potentially Improves Lightning Network: Combined, CTV and CSFS could make Lightning payment channels more reliable and efficient (e.g., enabling “ln-symmetry”), addressing a known technical limitation.
- Offers Path for Controlled Protocol Evolution: Integrating these mature, tested opcodes into Bitcoin Core (for later community evaluation) represents a practical step to add useful functionality while maintaining Bitcoin’s security and minimalist design principles.
The letter details the history of both proposals. CTV was formally proposed over five years ago in BIP-119. Despite refinements, it remains the preferred method for enforcing pre-set transaction sequences. CSFS has been implemented in Blockstream’s Elements project for at least eight years. The signers state CSFS requires similar computing power to Bitcoin’s existing OP_CHECKSIG opcode.
These operating codes enable functionality for a broad set of uses that seek to enable preserving and expanding Bitcoin’s role as a scarce, censorship-resistant store of value.
Bitcoin Core Charter.
They argue both proposals are mature, technically moderate in impact, and have been extensively reviewed over their combined 13 years of existence. This coordinated effort represents a quiet but determined push to overcome the careful scrutiny that typically slows Bitcoin protocol upgrades.
Bitcoin (BTC) is trading at $108,776 USD, experiencing a −1.39% decline on the day. Despite the short-term drop, BTC is up +2.71% over the past week, +3.77% over the past month, and boasts a +16.51% year-to-date gain, along with an impressive +56.15% increase over the last year. The broader technical and fundamental structure continues to support a long-term bullish bias.
Technically, Bitcoin has successfully broken above its 20-day EMA ($105,296) and key resistance at $106,794, forming an inverted head-and-shoulders pattern with a projected target near $146,892.
The current price action shows BTC consolidating just below its all-time high of $112,000, set on May 22, 2025. Traders are closely watching the $109K–$112K range as a decision zone; a confirmed breakout could accelerate the rally toward new highs, while a rejection might trigger a short-term pullback to the $104K–$105K support area.
