What is xstrkBTC?
xstrkBTC: Liquid staking for shielded Bitcoin
xstrkBTC is the liquid staking token issued by Endur for staked strkBTC, Starknet's shielded Bitcoin asset. It is the fifth BTC LST on Endur and the first that carries optional privacy properties through to the staked position.
What is strkBTC?
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 to a multi-institution federation multisig. Issuance was ratified by SNIP-38 and SNIP-39.
strkBTC operates in two modes:
Mode
Behaviour
Unshielded
Standard ERC-20. Public balances and public transfers.
Shielded
Private balances and transfers. Amounts and counterparties hidden via Starknet zk-STARK proofs.
Mode is reversible. Holders move between shielded and unshielded contextually without bridging into a different token.
For background on strkBTC's underlying technology, see Starknet's STRK20 standard
What is xstrkBTC?
xstrkBTC is the LST that represents staked strkBTC on Endur. Like the rest of Endur's BTC LST stack, it is yield-bearing through exchange rate appreciation. Unlike the rest, xstrkBTC inherits the privacy properties of its underlying.
Key properties:
1:1 to staked strkBTC at issuance, exchange rate rises with rewards
Yield is paid in strkBTC (the same asset deposited)
Composable across Starknet DeFi: lending, LPs, vaults
Inherits the shielded or unshielded mode of the underlying strkBTC
Withdrawals tracked by NFT, with deposit-withdrawal matching for faster exits
How yield works
Starknet's protocol allocates a portion of total STRK emissions to BTC stakers.
Endur receives those STRK rewards on behalf of the strkBTC delegated through its validator registry.
A swap extension converts STRK into strkBTC at protocol-routed venues.
The strkBTC accrues into the vault, raising the xstrkBTC ↔ strkBTC exchange rate.
The xstrkBTC token balance does not change. The amount of strkBTC redeemable per xstrkBTC increases over time.
There is no rebasing, no airdrop dependency, and no off-chain reward distribution.
Privacy: what is public, what is private
State
Visibility
xstrkBTC ↔ strkBTC exchange rate
Public
Total supply of xstrkBTC
Public
Validator set and reward flows
Public
Aggregate vault state
Public
Individual strkBTC and xstrkBTC balances (in shielded mode)
Private
Transfer amounts and counterparties (in shielded mode)
Private
Privacy applies to user state, not to protocol state. Solvency and yield accounting remain auditable. For compliance use cases, viewing keys allow selective disclosure of strkBTC activity through a threshold-controlled auditing entity.
Fees
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, not to principal. Entering and exiting xstrkBTC is free.
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