Drivechain
Drivechain is a proposed Bitcoin sidechain design by Paul Sztorc that would let miners custody pegged bitcoin through long hashrate-voted withdrawals and would let those miners collect sidechain fees through blind merged mining. The design is specified mainly as BIP 300 (hashrate escrow) and BIP 301 (blind merged mining). Neither BIP is activated on Bitcoin mainnet, and consensus change proposals implementing them have not been merged into Bitcoin Core.
Hashrate escrow
BIP 300 introduces hashrate escrow outputs that lock bitcoin to a named sidechain. Withdrawals are proposed as compact commitments. Miners then vote in coinbase signals over a long period measured in months. If enough cumulative work supports a withdrawal proposal through the voting window, the escrow releases mainchain bitcoin to the withdrawal destinations. BIP 301 describes blind merged mining, in which sidechain block producers compete to pay Bitcoin miners for inclusion of a sidechain tip commitment without requiring those miners to fully validate the sidechain. A Bitcoin Core pull request attempting BIP 300 consensus logic (PR 28311) was opened as a work in progress and later closed without merge. No BIP 300 or BIP 301 rules are enforced by Bitcoin mainnet nodes today.
Hashrate escrow voting is intentionally slow so that a hostile withdrawal can be rejected by honest hashpower before coins leave the mainchain lock. Sidechain operators still need their own consensus rules, block producers, and users. Blind merged mining pays Bitcoin miners for committing to a sidechain tip without requiring those miners to run full sidechain validation. Critics argue that miner custody of pegged coins concentrates trust in hashpower and that failed withdrawals or soft-fork politics could strand sidechain users. Supporters argue the design avoids federated peg custodians and reuses Bitcoin's existing proof-of-work security budget.
BIP 300 withdrawal windows are measured in thousands of blocks so that hashpower can respond to a contested peg-out before coins unlock. A minority of miners cannot instantly steal escrowed value, but a persistent majority could still vote through a dishonest withdrawal. Sidechain nodes must watch mainchain coinbases for those votes independently of ordinary Bitcoin wallet software.
Blind merged mining
Blind merged mining commitments are small mainchain outputs or coinbase fields that name a sidechain tip. Miners choose among competing commitments by fee, similar to other optional coinbase services. If mainchain miners ignore a sidechain, that chain's tip progress stalls even when its own users remain active.
Sidechain block producers still compete among themselves under BIP 301. Mainchain miners only select which tip commitment to include, typically by fee, without validating sidechain transactions.
Status
Neither BIP 300 nor BIP 301 is active on Bitcoin mainnet. Bitcoin Core has not merged consensus code for hashrate escrow. Designs such as federated pegs or BitVM-style bridges use different trust assumptions and do not require miner withdrawal voting.