Crypto glossary
Drivechain (BIP-300)
Drivechain is a proposal, set out in BIP-300 and BIP-301, to let Bitcoin miners secure sidechains and approve withdrawals back to the main chain.
Developed mainly by Paul Sztorc, drivechain would add two soft-fork changes. BIP-300 creates hashrate escrows: bitcoin is locked on the main chain and can only be released to a sidechain user after miners vote for the withdrawal over a long period, roughly three months. BIP-301, blind merged mining, lets sidechain blocks be produced and paid for without miners running the sidechain software themselves.
Supporters argue drivechains would allow experimentation, such as privacy chains, larger blocks or smart contracts, without changing Bitcoin itself, and would give miners new fee revenue as the block subsidy shrinks. Users who dislike a sidechain could simply ignore it.
Critics worry that giving miners custody votes over large sums creates incentives to steal, or invites pressure from governments and large holders, and that it could draw miners into politics around sidechain activity. Others question whether users would accept months-long withdrawal delays. The proposal has been debated since 2015 without the broad consensus a soft fork needs.
Example
Under drivechain, a user moving 1 BTC back from a sidechain would wait while miners signal approval in block after block for about three months before the coins are released on Bitcoin.