Does Monero offer an equivalent of Check Lock Time Verify (CLTV) transactions? If not are there any major CryptoNote or RingCT specific obstacles that would prevent such a feature from being added in the future?

CLTV transactions would have many privacy focused applications.

1 Answer 1


There is a command to lock coins when you make a transaction by RPC in simplewallet. I don't think it's implemented in the command line interface. It's the unlock_time parameter in the JSON RPC transfer, described in the source code here:

uint64_t unlock_time;  //number of block (or time), used as a limitation like: spend this tx not early then block/time 

I think if you pass it an integer smaller then the current unix time in seconds, then it will interpret it as a number of blocks, and if it is larger than the unix time then it is interpreted as a time when the coins can be spent, or if it is zero then the funds can be spent immediately.

You can find a description of the JSON format for making RPC transfers and an example of one here: https://wiki.bytecoin.org/wiki/Simplewallet_JSON_RPC_API

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    The semantics of this lock time are different from bitcoin's, just so things are clear to the asker. In bitcoin, it means to not mine this tx IIRC. In Monero, it gets mined, but can't then be spent before the lock time delay.
    – user36303
    Jul 22, 2016 at 8:30
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    @user36303 thanks for clarification. If it gets mined then what is the purpose / use case for that? Except forcing oneself to HODL ;)
    – qertoip
    Dec 29, 2017 at 10:07
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    It is incorrect that CLTV in Bitcoin means "to not mine this tx". With CLTV, the transaction will be mined immediately, but a "time lock" will be placed on the specified UTXO for a given block height or timestamp. Once this criteria is met, the UTXO can then be spent.
    – Sharpiro
    Mar 25, 2018 at 17:47

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