Starknet is trying to turn Bitcoin into something more specific than another wrapped asset. Its new pitch is strkBTC, a Bitcoin-backed token on Starknet built for private transfers, selective disclosure and a longer-term security model shaped around post-quantum concerns.
In the article by Castle Labs, translated by TechFlow, the argument starts from two pressure points that are becoming harder to ignore as onchain finance moves closer to traditional markets. One is that asset flows on public blockchains remain visible to everyone. The other is that the cryptographic signatures supporting those systems face a future threat from quantum computing.
Bitcoin, the piece argues, is where both issues are easiest to see. It says Bitcoin still accounts for more than 56% of total crypto market capitalization and remains the anchor asset for the broader market, even though it offers little programmability on its own. To make Bitcoin usable in onchain finance, it has been bridged out and turned into wrapped tokens that can move through DeFi systems.
But higher yield is not the full story. The article says Bitcoin in DeFi also needs a way to move in size without broadcasting every transfer to the public, and it needs some assurance that it will still be secure if quantum machines eventually become powerful enough to challenge today’s signature schemes.
That same standard, the authors argue, applies to other digital assets as well. Assets need to move, settle and combine onchain without exposing every position to the public, and they should not rely forever on cryptography that may not survive the next decade. Starknet, in this framing, is one of the protocols that recognized both constraints early and started building around them.
The piece says Starknet’s earlier BTCFi push this year was not just about making Bitcoin available onchain. It was also about using Bitcoin as a first clear test case for what users and institutions actually want: privacy by default, disclosure when needed, and technical hardening ahead of a post-quantum future.
It also refers to Starknet’s earlier work and messaging on this front, including why $2 trillion worth of Bitcoin remains idle, how its roadmap approaches a trust-minimized Bitcoin path, what its STRK20 privacy framework is meant to do, and why it has described the system as privacy through ownership.
Privacy and the quantum timeline
The article revisits a core blockchain principle: don’t trust, verify. Public chains let anyone inspect balances, trace transfers, monitor flows and review contract activity. That transparency helped establish trust in the early model.
Still, the same transparency can erode intellectual property, strategy, personal safety and operational privacy. The authors say that is even more acute now because AI-driven de-anonymization can link public addresses to real-world identities with up to 90% accuracy.
In that context, privacy is presented as infrastructure, not a luxury. Individuals need it to reduce surveillance, profiling, harassment, crime and political exposure. Institutions need it to keep holdings, order flow and related data confidential, while avoiding counterparty visibility and strategy leakage. At the same time, the model needs to allow selective disclosure to auditors, regulators or internal compliance teams.
The article then runs through the tradeoffs that earlier privacy efforts exposed:
- Purely anonymous privacy pools such as Tornado Cash ran into compliance pressure, including OFAC sanctions and criminal charges and imprisonment for developers.
- Privacy coins such as Monero and Zcash showed that hidden transfers are possible, but struggled to integrate with the wider onchain economy and at scale with DeFi primitives.
- Private execution systems such as Aztec identified early demand for private DeFi, but often faced high costs, fragmented liquidity and weak user experience.
The piece also links privacy shortfalls to physical-world danger. Citing CertiK, it says there were 34 verified physical attacks against crypto holders in the first four months of 2026, up 41% year over year, and adds that these incidents are widely underreported. In France alone, it says, there were 41 crypto-related kidnappings from January through May 2026, or one every 2.5 days.
That is why privacy, in the authors’ telling, is no longer only about hiding trading activity or protecting alpha. It is also about reducing personal and operational risk.
Alongside that issue sits another one: quantum computing. The article argues that a path that solves both visibility and durability could move blockchains closer to becoming next-generation financial infrastructure.
It points to a March report from Google Quantum AI co-authored by Ethereum Foundation researcher Justin Drake and Stanford professor Dan Boneh. That report identified several attack paths and estimated that about $100 billion in the Ethereum ecosystem is at risk. It also singled out Starknet as having a stronger post-quantum position than other major L2s because its proving system is based on hash-based STARK assumptions rather than elliptic-curve cryptography.
The report focused on exposed secp256k1 public keys linked to Bitcoin and Ethereum wallets and said a sufficiently capable quantum computer could attack wallets in under nine minutes. The article adds that Justin Drake later warned there is “at least a 10% chance” that quantum computers could recover private keys from exposed public keys by 2032.
That is not today’s reality, the piece says, but it already raises questions about assets meant to be held for decades. As Bitcoin is used more often as collateral, reserve property and a balance-sheet asset for institutions, its privacy and security requirements rise with it.
strkBTC as private Bitcoin on Starknet
Wrapped Bitcoin is not new. It lets BTC move into other ecosystems and become tradable, lendable and usable as collateral or liquidity. What it has not solved, the article says, is visibility.
Even if wrapped BTC becomes productive capital, every movement can still be monitored, inspected and traded against. Deposits, loans, swaps, LP positions, repayments, withdrawals, wallet clustering and treasury flows all remain public by default. The authors argue that serious financial markets do not work that way, and onchain finance will keep running into an institutional ceiling until that changes.
Traditional finance, by contrast, bakes privacy into the infrastructure. The article notes that a significant share of stock trading volume moves through dark pools and other private or over-the-counter venues. Counterparties see what they need to see. Regulators retain access when needed. The public sees aggregated volume, not every live transfer.
Crypto, the piece says, has treated visibility as the norm when privacy should be the baseline. That is the context for strkBTC.
According to the article, strkBTC is an ERC-20 on Starknet backed by BTC locked on the Bitcoin network. It is built on StarkWare’s STRK20 framework, which is designed to shield balances and enable private transfers.
STRK20 gives strkBTC two operating modes.
- In public mode, it behaves like a standard ERC-20. Users can hold it, transfer it, supply it to lending markets, provide liquidity or use it as collateral.
- In shielded mode, selected balances and transfers are hidden from public view. Users can shield funds, transact privately and unshield directly in the wallet to move back to public balances.
The article says Starknet v0.14.2, the upgrade that enabled STRK20, changed the economics of proof verification. Before that, applications that wanted to verify STARK proofs on Starknet had to do so inside smart contracts, which was expensive and complex because the proofs were large. Now transactions can reference offchain proofs directly, while Starknet consensus handles verification natively through protocol-level proof validation.
That shifts privacy into the protocol layer rather than forcing users into separate applications, chains, pools or mixers. The article says that reduces complexity, cost and liquidity fragmentation, and lets builders spend more time on products because the underlying infrastructure already supports private operations.
Compliance is built into the design as well. When users shield strkBTC, the relevant viewing keys are shared with Financial Privacy Inc, or FPI, which the article describes as an independent third-party audit firm operating compliance infrastructure for STRK20. FPI can grant scoped access in response to valid regulatory requests.
The authors acknowledge that this may not satisfy the purest cypherpunk view, but say it fits traditional market structure much more closely: privacy from the public, disclosure to regulators when required.
The bridge follows the same logic. For now, the strkBTC bridge is run by a trusted consortium made up of Twinstake, NEAR Intents, Luganodes, UTXO Management and Xverse. Those independent signers support minting and burning between BTC and strkBTC. The consortium is described as a starting point, not the final form, and Starknet says it plans to harden that roadmap over time.
In the article’s framing, strkBTC is not trying to be another wrapper. It is meant to unlock a programmable and composable form of BTC whose movement is not broadcast to everyone, addressing the visibility problem first.
The quantum problem for blockchains
Every blockchain relies on public-key cryptography. When users sign transactions, they reveal public keys while keeping private keys hidden. On Bitcoin and most other chains, that has long been treated as routine and secure.
In a post-quantum world, that assumption becomes less stable. A sufficiently capable machine running Shor’s algorithm could, in theory, derive private keys from exposed public keys. If that happens, public-key exposure stops being a harmless part of transaction verification and turns into an attack surface. The article stresses that this is not unique to one network, because Bitcoin, Ethereum and Solana all sit on related elliptic-curve foundations.
The threat is shared. The ability to respond is not. The chains with the greatest exposure are often the ones that move the slowest, and the article casts Bitcoin as the clearest example.
Bitcoin, it says, is not short on ideas for a post-quantum future. The hard part is getting broad agreement on the tradeoffs the network is willing to accept: larger signatures, higher costs, what to do with legacy coins, user migration, wallet support, miner policy, and whether dormant or unmigrated coins should be frozen.
That makes Bitcoin’s quantum problem technical, social and political all at once. Dan Boneh, one of the co-authors of the Google report, is quoted from a recent interview saying, “Bitcoin should not panic, but it also cannot ignore this. Moving too fast could be worse than waiting, because a rushed post-quantum migration could introduce catastrophic bugs before quantum becomes a real-time attack.”
The article’s conclusion on this point is that Bitcoin may solve its quantum problem, but probably not quickly or cleanly. That slow pace can be a feature of sound money, yet it also leaves room for more agile stacks to build durability that the base layer itself cannot promise yet.
Ethereum and the L2 networks that scale it are not exempt. Most rollups settle to Ethereum and depend on it for data availability, so they inherit some of the base layer’s exposure. Ethereum has published its own multi-year migration plan, but until that plan is executed, chains built on top of it remain exposed to Ethereum’s post-quantum timeline.
Why the article says Starknet has an architectural edge
The piece attributes Starknet’s position to two design decisions made before quantum computing became an immediate topic.
The first is the proving layer. Starknet generates STARK proofs to secure every state transition on the network, and those proofs rely on hash functions rather than the elliptic-curve math quantum computers are expected to threaten most directly. The article says this design choice dates back to a 2018 paper co-authored by StarkWare CEO Eli Ben-Sasson. That layer is central to the network’s security model, and it is why the Google paper described Starknet as the only major L2 already ahead on this front.
The second is native account abstraction. On many chains, signature schemes are fixed at the protocol level, so replacing them can require a hard fork and coordinated migration across users and applications. Starknet accounts can define how they verify identity, which means users can move to quantum-resistant signatures without changing the protocol layer itself.
StarkWare says a quantum-resistant wallet called S2morrow has already been deployed with Falcon-512, and OpenZeppelin is building a standardized version. The article presents that as a meaningful difference. On many chains, this kind of switch would imply a protocol-wide migration. On Starknet, much of the work can start at the wallet level. That does not mean every Starknet wallet is quantum resistant today, but it does mean the path is easier.
StarkWare also released a roadmap last week aimed at delivering end-to-end post-quantum security for Starknet before a future Q-day, the point when quantum computers become powerful enough to break modern cryptography. The article says that roadmap is split into three phases, though it does not detail those phases in the text presented here.
It also makes a point of saying none of this means Starknet is fully post-quantum today, and the roadmap does not claim otherwise.
What still needs to be proven
The article lays out the remaining gaps directly. Starknet may be able to replace Pedersen with BLAKE2, improve wallet support and create migration paths for legacy contracts, but it cannot remove every risk inherited from the base layer. Bridge messaging and blob data availability still depend on Ethereum’s own post-quantum roadmap.
So while Starknet can harden the parts it controls, the parts inherited from Ethereum will move on Ethereum’s schedule. The article notes that the Ethereum Foundation has already outlined structured fork milestones with the aim of delivering core post-quantum infrastructure around 2029.
strkBTC has its own staged path as well. Today the bridge relies on a consortium to coordinate minting and burning between BTC and strkBTC. That is a trusted starting point, not the ideal trustless end state. Starknet’s target is to move from the consortium model to Bitcoin-native verification, then to a less trusted BitVM design, and finally, if Bitcoin enables the required opcodes in the future, to a fully trustless design based on OP_CAT.
Viewing keys are another unresolved part. The article describes them as Starknet’s practical answer to institutional privacy: opaque to the public, selectively visible when required. But they have not yet been stress-tested in real-world conditions, raising questions about who can request disclosure, under what standards, and what safeguards will apply.
The article closes with a broader point. Digital assets, including Bitcoin, do not need one more wrapper. They need surrounding infrastructure that lets them operate onchain without sacrificing the two things institutions care about most: confidentiality today and durability in the future.
In that framework, strkBTC addresses confidentiality by giving BTC a private and selectively disclosable route into DeFi. Starknet’s current architecture and roadmap address durability: its proving layer already avoids the elliptic-curve assumptions that create heavy post-quantum migration debt elsewhere, and its roadmap extends that advantage to the remaining parts with the stated goal of making Starknet quantum-safe before Q-day.
The outcome is still early, the article says, but the direction is clear. The next institutional phase of onchain finance will need more than yield. It will need privacy, compliance, programmability and durability built into the same stack.