Bitcoin doesn’t do much, but what it does do, it does extremely well. For security, verifiability, and data integrity, Bitcoin is unrivaled. Its decentralized network is great for sending, receiving, and storing BTC. And, with a little tinkering, it’s also capable of hosting non-fungible assets such as Ordinals and Runes. But beyond that, Bitcoin is extremely limited.
Satoshi Nakamoto’s decision to give Bitcoin a sparse feature set was a masterstroke that’s one of the reasons it’s still here today. But 15 years into cryptocurrency’s existence, our understanding of what can be safely done with blockchain technology has evolved. While major modifications to Bitcoin’s base layer are rightly opposed by its community, there’s nothing to stop developers from extending Bitcoin’s utility on subsequent layers and chains – which is exactly what they’ve done.
These interoperability solutions endeavor to retain the robust security and transaction finality for which Bitcoin is renowned while extending its reach to new networks, layers, and use cases. Thanks to these innovations, Bitcoin is no longer magic internet money: it’s yield-generating magic internet money.
Overcoming Bitcoin’s Limitations
As a single-layer protocol primarily focused on the transfer of value, Bitcoin doesn’t natively support smart contracts and decentralized applications. Its scripting language (Script) is non-Turing complete and limited in functionality, restricting its ability to interact with other blockchains and to execute more complex operations. Developers seeking to increase Bitcoin’s interoperability have approached this challenge from a number of angles.
At the most basic level, the ability to lock BTC into a multisig on Bitcoin and issue a corresponding wrapped token on another chain, such as Ethereum, allows BTC to escape its confines. While this is useful for allowing multichain users to gain exposure to BTC, it’s not “true” Bitcoin DeFi since a wrapped token inherits none of the security guarantees or network effects synonymous with Bitcoin.
Rather than bringing Bitcoin to the multichain world, an alternative option is to bring multichain to Bitcoin by building up the stack. This entails creating a sidechain or layer 2 that inherits Bitcoin’s security model and allows BTC to be trustlessly bridged both ways.
One of the earliest attempts at constructing a Bitcoin DeFi ecosystem, RSK, was ahead of its time as a concept but has struggled to secure the users and developers that make the difference between a network and an ecosystem. A similar problem has been faced by Lightning Network, whose complexity has proven a deterrent to many would-be users.
It turns out that making Bitcoin interoperable and also usable is a delicate balancing act. But where there’s a will there’s a way and a new wave of interoperability solutions is coming onstream that seek to overcome the limitations of the first wave of scaling projects.
Building Trust Minimization Into Bitcoin
Bitcoiners trust code, not people. In an industry awash with hackers, scammers, and phishers, cryptography is one of the few things that can be trusted. For this reason, most holders have been hesitant to entrust their precious BTC to more complex systems that increase risk – despite the alluring rewards for doing so. Until relatively recently, attempting to extend Bitcoin’s reach meant introducing custodial risk, as is the case with assets like WBTC.
Flare, one of the blockchain protocols trying to solve this challenge, has had to implement a raft of measures to create its own tokenized representation of BTC that doesn’t rely on gatekeepers. FAssets, the name for the non-native tokens that can be bridged to Flare, are secured in three ways: through over-collateralization (e.g. locking up more BTC than the value bridged); using decentralized time oracles for accurate price feeds; and a separate data connector oracle to verify payments on the Bitcoin network.
No one said scaling Bitcoin would be easy. Meanwhile, other interoperability projects are making progress building on top of Bitcoin. Rather than forcing developers to master unfamiliar programming languages and tooling, L2s such as Merlin Chain have utilized the trusty EVM. Making Bitcoin more Ethereum is an attempt to have the best of both worlds, combining the security and liquidity of the former with the smart contract capabilities of the latter.
Will the Market Anoint a Winner?
Solutions such as Flare’s FAssets and Merlin’s L2 both extend BTC’s reach and utility, yet aren’t in direct competition with one another. Nevertheless, the number of L2s, sidechains, and bridges intent on scaling Bitcoin is starting to stack up. They can’t all succeed: markes usually settle on one or two dominant players and discard the rest.
Three years ago, Bitcoin didn’t have enough interoperability options. Now, it might have too many. This is a problem that should self-correct as the solutions that find product-market fit exert dominance and users and liquidity flows to them. What matters is that Bitcoin is now much more than an idle asset. Those who want to hodl can just hodl. Those who want to do more with their digital money have an array of DeFi opportunities just a non-custodial bridge away.
