Introducing xstrkBTC: the LST for Starknet's shielded Bitcoin
Bitcoin staking has scaled into a multi-billion dollar market in under two years. Total BTC committed across staking and DeFi protocols has grown close to 2,700% year on year. Bitcoin liquid staking alone has crossed the multi-billion dollar mark, with tens of thousands of BTC routed into LSTs and onto money markets across multiple chains.
The supply curve for productive BTC is steepening. Utilization is not.
Less than 1% of total BTC supply is actually deployed in DeFi money markets today. The bottleneck is not yield. BTC staking yields are competitive, LSTs are widely accepted as collateral, and lending markets are deep. The bottleneck is the ledger. Productive BTC sits on transparent chains where balances, transfers, and collateral positions are visible by default. For holders who treat position privacy as a hard requirement, treasuries, funds, family offices, individuals with security exposure, that default is a ceiling.
xstrkBTC sits on the other side of that ceiling. It is the liquid staking token for strkBTC, Starknet's shielded Bitcoin asset, and it brings staking yield to BTC without forcing balances onto a public ledger.
What strkBTC is
strkBTC is Starknet's native shielded Bitcoin. Each unit is 1:1 backed by BTC, redeemable for native BTC, and issued deterministically against verified deposits. There is no discretionary minting. The peg is enforced at the protocol level.
Issuance is governed by a multi-institution federation operating a Bitcoin multisig, with a minimum of five independent members, ratified by SNIP-38 and SNIP-39 passing governance near-unanimously. Minting follows a deterministic path. A user deposits BTC to the federation's multisig address. Members independently verify the deposit on Bitcoin. Once the confirmation threshold is met, members co-sign a minting transaction on Starknet that issues strkBTC to the depositor. Burning runs the same path in reverse, with the federation co-signing a Bitcoin release once the burn event is verified on Starknet.
The federation is a bootstrap trust assumption, not the endpoint. The design moves through three phases. Phase 1 is the multisig federation in operation today. Phase 2 introduces BitVM-based verification. Phase 3 targets full trust-minimization via OP_CAT and advanced Bitcoin scripting. The trust surface narrows at every step.
What separates strkBTC from WBTC, tBTC, or SolvBTC is optional privacy at the asset layer, powered by Starknet's zk-STARK cryptography. strkBTC operates in two modes:
Unshielded. Behaves like a standard ERC-20 token. Public balances, public transfers.
Shielded. Balances and transfers are private. Amounts and counterparties are hidden using zero-knowledge proofs.
Mode is reversible. Holders move between shielded and unshielded contextually without bridging or wrapping into a different token. Liquidity stays unified across both states. There is no separate shielded contract, no fragmented anonymity set, no second asset to onboard.
Privacy is built into the asset itself. No mixers, no external tooling. For situations that require disclosure, holders generate viewing keys, encrypted credentials registered through a threshold-controlled auditing entity, to selectively reveal balances or activity without exposing the rest of the ledger.
Composability is preserved in both modes.
xstrkBTC: making shielded Bitcoin productive across Starknet DeFi
xstrkBTC is the liquid staking token issued by Endur for staked strkBTC. It is a Starknet-native, fully transferable token that bundles three properties into a single position: a claim on staked strkBTC, an accruing yield position from Starknet protocol rewards, and a composable collateral primitive across Starknet DeFi.
Yield accrues through exchange rate appreciation. The xstrkBTC balance stays constant. The amount of strkBTC redeemable per unit of xstrkBTC rises as staking rewards settle into the vault. The yield is structural, not promotional. No rebasing schedules, no airdrop layer, no off-chain accounting to trust.
Underneath xstrkBTC, Endur is building the utilization layer for shielded Bitcoin on Starknet. The architecture is a vault and delegator system. Deposited strkBTC is routed to a registry of curated validators. Staking rewards land in STRK and pass through a swap extension that converts them into strkBTC at protocol-routed venues. The strkBTC accrues into the vault, raising the xstrkBTC ↔ strkBTC exchange rate. Withdrawals are mediated by an NFT-tracked queue with deposit-withdrawal matching for faster exits.
The result is a single token that can move across the Starknet DeFi stack without losing its yield or its privacy:
Liquidity provision. Pair xstrkBTC on Ekubo to earn AMM fees on top of staking yield. Two yield streams from one asset, deep routing into and out of the position.
Lending and borrowing. Post xstrkBTC as collateral on Vesu to borrow stablecoins or other assets against shielded BTC exposure. Positive carry stays intact across the loop, since the underlying strkBTC keeps accruing.
Vaults and structured strategies launching soon on Troves fi
For the first time, shielded BTC becomes productive without leaving the shielded state. The same token that earns Starknet staking yield is the same token that earns lending interest, LP fees, and vault returns. Liquidity is unified across both privacy modes, not fragmented into separate shielded and unshielded versions of the asset.
This is the gap xstrkBTC closes. Privacy without utility was a half-solution. xstrkBTC turns shielded BTC into a composable building block across the full Starknet DeFi stack.
What is public, what is private
Privacy applies to user state, not to protocol state. Solvency and yield accounting remain auditable.
What is public:
The xstrkBTC ↔ strkBTC exchange rate
The total supply of xstrkBTC
The validator set and reward flows
Aggregate vault state
What is private (in shielded mode):
Individual balances of strkBTC and xstrkBTC
Transfer amounts and counterparties
Fees and mechanics
xstrkBTC mirrors the fee structure of the rest of the BTC LST stack on Endur.
| Item | Detail |
|---|---|
| Stake fee | 0 |
| Redemption fee | 0 |
| Performance fee | 15% on earned rewards only |
| Yield mechanism | Exchange rate appreciation, not rebasing |
The performance fee applies to rewards, never to principal. Entering and exiting xstrkBTC is free.
Withdrawals
Native Starknet BTC unstaking takes roughly 7 days. Endur shortens that path through deposit-withdrawal matching. Incoming strkBTC deposits are routed to satisfy outgoing redemption requests, allowing exits to clear faster than the protocol-level queue.
When matching is unavailable, withdrawals enter a queue. Each request is tracked by an NFT representing the holder's place in line and the amount owed. The NFT can be held, transferred, or used as the claim instrument when the redemption is settled.
Queue processing is first come, first served.
Where xstrkBTC fits in Endur's LST stack
xstrkBTC is the sixth liquid staking token issued by Endur, and the fifth on the BTC side.
| LST | Underlying | Privacy |
|---|---|---|
| xSTRK | STRK | Public |
| xWBTC | WBTC | Public |
| xtBTC | tBTC | Public |
| xsBTC | SolvBTC | Public |
| xLBTC | LBTC | Public |
| xstrkBTC | strkBTC | Optional shielded |
The mechanics are identical across the BTC LSTs. Same exchange rate model. Same fee schedule. Same withdrawal architecture. The variable is the underlying asset, and with xstrkBTC, the privacy properties the underlying carries.
The privacy horizon
xstrkBTC is the first liquid staking token where privacy is intrinsic to the underlying. It will not be the last.
The shift is structural. Productive capital on public chains has carried a permanent tradeoff: yield and composability on one side, balance privacy on the other. STRK20, Starknet's token standard for built-in privacy, removes that tradeoff at the asset layer. Any ERC-20 issued under it carries shielded balances, private transfers, reversible mode switching, and threshold-controlled selective disclosure. Stablecoins, governance tokens, real-world asset tokens, and any other ERC-20 can move under the standard without surrendering DeFi composability or auditability. Anonymous swaps are already live on Ekubo. Anonymous staking for BTC and STRK is active from the start.
The implication for liquid staking is direct. Endur's vault and delegator architecture is asset-agnostic. The same exchange rate model, fee schedule, withdrawal queue, and validator routing applies regardless of the underlying or its privacy mode. As more privacy-preserving assets come online, the LST stack expands with them.
Endur's role is the liquid staking layer for Starknet, including the privacy-preserving slice of it. xstrkBTC is the proof point. Yield, composability, and shielded state can sit in the same token without any of them eroding the others. Privacy stops being a tradeoff. It becomes a default that productive capital can opt into without leaving the rest of DeFi behind.
Frequently asked questions
What is xstrkBTC
xstrkBTC is the liquid staking token issued by Endur for staked strkBTC. It accrues staking rewards through exchange rate appreciation against strkBTC.
Is xstrkBTC private
xstrkBTC inherits the privacy mode of the underlying strkBTC. When the staked strkBTC is shielded, holdings and transfers stay private. The exchange rate, total supply, and protocol state remain public.
How is yield generated
Starknet allocates a portion of STRK emissions to BTC stakers. Endur receives those rewards through its validators, swaps STRK into strkBTC, and adds the strkBTC to the vault. This raises the redemption rate for xstrkBTC holders over time.
What are the fees
Zero stake fee. Zero redemption fee. 15% performance fee on rewards earned, not on principal.
How long do withdrawals take
Native unstaking is around 7 days. Deposit-withdrawal matching can clear redemptions faster when incoming deposits offset outgoing requests. Queue position is tracked by an NFT.
Can xstrkBTC be used in DeFi
Yes. xstrkBTC is composable across Starknet lending markets, DEXs, and vaults. The underlying strkBTC continues to accrue staking rewards while xstrkBTC is deployed elsewhere. For background on the broader BTC liquid staking model on Starknet, see Everything about Bitcoin Staking on Starknet.
