How Renbridge Worked — Mint & Release

The wrapping architecture of Renbridge relied on two primary smart contract actions: Minting (creating wrapped tokens from native assets) and Releasing (burning wrapped tokens to redeem native assets).

The Cross-Chain Minting Flow

Minting was the process of bringing native assets like BTC into smart-contract chains as renBTC. This flow was coordinated directly between the user, the Bitcoin blockchain, the RenVM network, and the destination network's smart contracts:

Gateway Generation: The user selected their destination chain (e.g., Ethereum) and requested a mint address. The RenVM Darknodes generated a unique, one-time Bitcoin gateway address using sMPC.
Deposit: The user sent native BTC to the generated gateway address.
Confirmation Wait: The RenVM network monitored the Bitcoin blockchain, waiting for the transaction to receive a set number of confirmations (typically 6 blocks).
Signature Delivery: Once confirmed, RenVM created a cryptographic signature verifying the deposit.
Minting Execution: The user submitted this signature in a transaction to the host network's Ren smart contract, which minted the matching renBTC tokens directly to the user's wallet.

The Releasing (Burning) Flow

Releasing was the opposite action, where users redeemed their wrapped renBTC for native BTC, destroying the wrapped token in the process:

Initiate Burn: The user called the burn function on the Ethereum or Polygon smart contract, specifying the quantity of renBTC to destroy and their native Bitcoin wallet address.
Observation: The Darknode network detected the burn event on the smart-contract chain.
Signature Creation: The nodes verified the event and collectively signed a Bitcoin transaction using sMPC.
Native Release: RenVM broadcasted the signed transaction to the Bitcoin blockchain, releasing the native BTC from the protocol's vaults directly to the user's wallet.

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