4 Years of tBTC

4 years since the September 2020 launch of tBTC v1, tBTC continues to be one of the few bridges that has never suffered a loss of funds. For those 4 years, and the 2 years of development that preceded them, the teams at Thesis and the Threshold Network that have worked on the tBTC infrastructure have been focused on the three principles outlined in tBTC is for L2s:

• Security first
• Credible neutrality
• Economic alignment

4 years of learnings

In the early hours of May 18, 2020, at the height of COVID restrictions and before front-running white hat hackers were commonplace or SEAL 911 was a twinkle in samczsun's eye, the Keep team paused the first release of the tBTC contracts in what was to be one of the rare cases in the crypto space of a team spotting a critical smart contract bug and avoiding all loss of funds. Following a detailed retro and four months of heavy additional testing, tBTC went live in its first version. Though this was the only time that the bridge has risked fund loss, the learnings from that event have translated into a rigorous, careful development process that has ensured the security of the bridge for the years that followed.

Once tBTC v1 launched, it became clear that one of the key challenges in scaling a bridge is its capital efficiency: how to balance security of user funds against the economic guarantees that those funds will remain available. This observation triggered the development of v2 of the bridge, whose design carefully balanced these two components to produce a decentralized Bitcoin bridge built for scaling. Launched in January 2023, this updated model has safely bridged over 11,000 BTC to date.

tBTC v1 launched with a phased approach, starting with a minting cap of 100 tBTC that slowly increased to 1000 and then was lifted altogether. When v2 went live, it was launched with a slower, safer minting process and no redemptions, and over time launched optimistic minting to make bridging complete in a handful of hours, followed by full redemptions to bridge back to the Bitcoin network a few months later. At each step, security was held paramount, with v1 undergoing 3 audits before launch and v2 doing phased audits as additional functionality came online.

4 years of changes

Though the original version of tBTC was built by the Keep Network, 2021 brought an opportunity for Keep Network and NuCypher, a similar project with a slightly different product portfolio, to merge into one joint DAO. In early 2022, the first decentralized merger was completed to create the Threshold Network, whose nodes now operate the systems that back tBTC bridging. In the intervening time, Threshold has become a full-fledged DAO with an associated legal entity, various guilds responsible for driving its priorities and products forward, bug bounty programs associated with tBTC and other protocols backed by the network, and more.

More recently, Threshold launched thUSD, a stablecoin backed by Bitcoin based on tBTC, which is now being used by the Threshold DAO to pay USD expenses. L2s from BOB to Mezo have been relying on tBTC to provide more use cases and possibilities to the world of Bitcoin. And finally, tBTC is being bridged from Ethereum to landmark chains like Base and Polygon and being minted natively on high-throughput chains like Solana and, soon, Arbitrum.

4 years is just the beginning

tBTC is starting to appear everywhere, but it's also just getting started. Both as a building block and as an infrastructure tool, tBTC promises to be instrumental in building out the networks that are adding productive uses to Bitcoin, including underpinning a new wave of native experiences for Bitcoin-native users like transparent access to Bitcoin wallets that want to interact with other chains. It's also the heir apparent as WBTC struggles with the usual complications of operating a centralized bridge.

On the backend, the development team has already started building out the use of FROST and ROAST to move the network from 51-of-100 wallets to 501-of-1000 wallets that provide full attributability for errors and aborts, allowing tBTC to scale its network even further. At the same time, the introduction of BitVM is being closely watched as another potential ugprade in security model and scale. As the technology matures, using the most diverse and experienced set of operators and the most trusted decentralized bridge and token as the premier BitVM implementation will become a natural choice.

Between core technology upgrades, L2 adoption, increased availability in blue chip DeFi protocols like Aave and GMX, new and more seamless integrations across existing and novel chains, and as-of-yet unexplored protocols built on top of the straightforward access to decentralized BTC collateral provided by tBTC, the coming years promise to be the most exciting yet.

Want to join in the fun? Start building with tBTC now.