Bitcoin: recovery and Lightning
Bitcoin timelocks: a calendar condition versus a coin’s age
Absolute and relative locks start their clocks in different places.
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Reference guides
Two kinds of waiting
An absolute timelock restricts spending before a specified block height or time condition. A relative timelock measures a delay from the confirmation of the output being spent. BIP-65 introduces CHECKLOCKTIMEVERIFY; BIP-68 and BIP-112 define the relative sequence-lock mechanism and CHECKSEQUENCEVERIFY. They do not use a human calendar in the same way as an appointment app. 1 2 3
A lock is a condition, not a scheduled payment
Reaching the required height or age can make a spending path eligible. It does not create a signature, pay a fee or broadcast a transaction. Other script conditions still apply. A recovery path can therefore combine a delay with a particular key; an owner must retain that key and a compatible way to construct the eventual spend.
Which clock is actually used?
Block-height locks depend on blocks, not guaranteed minutes. Time-based consensus checks use the specified median-time rules rather than a wallet’s local wall clock. Relative time locks use a defined granularity. Converting these mechanisms into ‘exactly 24 hours’ without explaining the assumptions gives users false precision. Wallet interfaces should expose the condition and whether it has become satisfied.
Recovery design needs an exit story
A delayed alternative can give an owner time to respond to an unwanted action, but only if someone monitors the relevant state and has a usable response path. A long delay can also lock a legitimate owner out during an emergency. Document who can use each branch, the starting event for the delay and what happens if the monitoring service disappears.
Worked example
An absolute path opens after block height H, regardless of when the output was funded. A relative path requiring 144 blocks starts from that output’s confirmation. Funding a new output tomorrow starts a new relative wait; it does not move the absolute height H.