Bitcoin on Citrea
cBTC represents the safest form of BTC on a fully programmable Bitcoin layer. Powered by Clementine Bitcoin bridge, cBTC relies on cryptographic security and is optimistically verified by the Bitcoin Network.
What makes cBTC Unique?
The most secure way to use BTC on a fully programmable layer.
First Trust-Minimized Bridging
cBTC is powered by Clementine, a 1-of-N bridge that doesn’t rely on custodians or multi-sig committees.
Bitcoin-Backed
cBTC is 1:1 backed by real Bitcoin locked on the Bitcoin mainnet. Every cBTC token represents actual BTC that can be redeemed.
Verifiable by Bitcoin
cBTC is verified optimistically by the Bitcoin Network. This means that any fraudulent bridge activity can be detected on the Bitcoin mainnet with at least one honest party present.
Composable Bitcoin Apps Ecosystem
Citrea’s composable ecosystem allows cBTC to move across different apps seamlessly. Users can trade cBTC, provide liquidity, earn yield and borrow against it.
What's Clementine Bridge?
Clementine is Citrea’s BitVM-based Bitcoin bridge. Historically, Bitcoin bridges have often relied on multi-signatures where users must trust a majority of signers (e.g., 3-of-5). Citrea’s trust-minimized bridge, Clementine, fundamentally shifts this security model using BitVM and cryptography. With Clementine, Citrea expresses a zero-knowledge proof verifier on Bitcoin and builds a trust-minimized peg mechanism around it.
Clementine offers trust-minimized bridging between Bitcoin and Citrea with a 1-of-N assumption, where a single honest participant is sufficient for the funds to be secure and for the system to be functional.
There are four important actors in Clementine bridge
Watchtowers
Watchtowers
Watchtowers are responsible for monitoring both Citrea and Bitcoin. In the case of a malicious event, Watchtowers publish the compact Bitcoin header-chain proof with total work.
Challengers
Challengers
Challengers are responsible for forcing an operator to prove their intent by initiating a challenge transaction and using the header-chain proof published by the watchtower.
Operators
Operators
Operators are incentivized to process user withdrawals and then get reliably reimbursed. In any case of a malicious Operator intent, Clementine initiates a challenge with other entities and protects the funds.
Signers
Signers
Signers are a committee that enforces Operators’ spending conditions. As long as a single honest signer exists, funds can only move along Clementine’s approved paths. Citrea’s signer lists are publicly disclosed.