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59 lines
2.6 KiB
Markdown
59 lines
2.6 KiB
Markdown
---
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summary: 'a special transaction where the recipient(s) can only spend the funds after a future date, as set by the sender'
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terms: ["unlock-time"]
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---
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{% include disclaimer.html translated="no" translationOutdated="no" %}
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### The Basics
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A special transaction where the recipient(s) can only spend the funds after
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a future date, as set by the sender.
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Unlock time allows you to send a transaction to someone, such that they can
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not spend it until after a certain block height, or until a certain
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time. These locks are per transaction, not per output. This means any
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returning change will be locked too. ***Do not unintentionally lock your
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change outputs.***
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Note that this works differently than Bitcoin's
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[nLockTime](https://en.bitcoin.it/wiki/NLockTime), in which the transaction
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is not valid until the given time.
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Using `unlock_time` has privacy consequences for the user(s) (and the wider
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Monero network if it is flooded with these). The value is public on the
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blockchain, so be aware of potential clustering. The feature is rarely used
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and may be removed in a future Monero release, so the Monero developers
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advise against building critical infrastructure that depends on this
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feature.
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Decoy outputs may be selected from these locked outputs, thus identifying
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them as provable decoy outputs. At the moment, this has little impact on
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wider network privacy since this unlock time feature is so rarely used.
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Further, true spends after a reasonably long lock time (more than several
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days) may be heuristically identified as the true spend, since there will be
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fewer other transactions using those outputs as decoys around that time
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period.
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Users should verify that the outputs they receive from others are not
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encumbered by an unexpected unlock time. Users may want to hold off acting
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upon such a transaction until the unlock time lapses. The `show_transfers`
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command includes the unlock time.
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### Technical Use
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Usage when using the `transfer` command: `unlock_time` + unsigned int
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Integer values less than 500,000,000 are interpreted as absolute block
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height. Values greater than or equal to 500,000,000 are interpreted as an
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absolute Unix epoch timestamp. The Monero CLI wallet only supports values
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less than 500,000,000; Unix timestamps must be submitted via RPC or another
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custom software.
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The integer value will be interpreted by the protocol as an ***absolute***
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block height value or Unix epoch timestamp, not a relative value. Using an
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integer value less than the current block height or a Unix epoch timestamp
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less than the current Unix epoch timestamp makes no sense. For example, if
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you want the Monero transaction to unlock 100 blocks from now, add 100 to
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the current block height.
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