Cardano’s research and engineering arm, Input Output Global (IOG), has unveiled “Cardinal,” the first protocol that allows native Bitcoin unspent transaction outputs (UTXOs) — including Ordinals — to circulate inside Cardano-based decentralized-finance markets without custodians or federations.
The disclosure came late Monday when IOG chief technology officer Romain Pellerin published a nine-part thread on X describing Cardinal as “a new primitive for Bitcoin,” adding that his team has “made history with the first cross-chain Ordinal wrap.” He summarized the design in a single sentence: “Bitcoin stays locked under MuSig2; the wrapped UTXO is minted cross-chain; it is redeemable at any time via fraud-proofed peg-out — no rehypothecation, no compromise.”
How The Cardano Bridge Works
Cardinal keeps the original satoshis on the Bitcoin base layer, secured by a MuSig2 aggregated multi-signature controlled by a rotating operator set. A hashed-timelock contract (HTLC) defines the conditions under which the funds may be reclaimed; on the Cardano side, an extended-UTXO (eUTXO) smart contract mints a 1:1-pegged non-fungible token that represents the locked UTXO. Off-chain verification is supplied by BitVMX, a verifiable-execution framework that publishes fraud proofs to Bitcoin if an operator cheats. Pellerin noted that the “1-of-n honest” assumption keeps the bridge closer to Bitcoin’s own security model than today’s federated walk-arounds such as wBTC.
Because every wrapped output is itself an NFT, Ordinals retain their on-chain provenance when they cross the bridge. Once resident on Cardano, the wrapped satoshis or Ordinals become fully programmable assets that can be deposited on automated-market-maker pools, lent out for yield, or used as collateral without relinquishing ownership of the underlying inscription. “Ordinals can now be used in DeFi, serve as collateral, be auctioned across chains, borrow / lend value without losing provenance,” Pellerin wrote.
Custodial and federated bridges such as BitGo’s wrapped-Bitcoin contracts on Ethereum have dominated the $8.7 billion BTC-on-DeFi market but have also introduced single-point-of-failure and rehypothecation risks. The bridging sector has lost more than $2.5 billion to exploits since 2021, according to public incident trackers. Cardinal’s one-of-n MuSig2 model aims to shrink the trust surface while retaining capital efficiency: redeeming the NFT triggers a burn on Cardano and an unlock on Bitcoin, with BitVMX proofs published if an operator withholds the release.
Cardano’s eUTXO accounting mirrors Bitcoin’s own UTXO structure, simplifying the mathematical equivalence proofs required for a symmetric peg. Low fee volatility, native tokenization (no ERC-721 wrapper layer) and deterministic, script-level transaction costs further influenced the choice, Pellerin said. Nevertheless, the specification released on GitHub is chain-agnostic; extensions for Ethereum, Solana and Avalanche are already sketched in the repository.
Cardano founder Charles Hoskinson amplified the announcement to his 1.5 million followers, writing: “Welcome to the first Bitcoin DeFi protocol developed for Cardano.”
Cardinal is not yet a turnkey consumer product. Pellerin stressed that the release is “infrastructure” and called for external contributors to improve SNARK-based burn-proof generation, recursive state proofs and wallet UX. Independent auditors will also need to scrutinize the MuSig2 implementation and operator rotation logic, both frequent failure points in prior bridge exploits.
At press time, ADA traded at $0.6984.
