Bitcoin Forum

Hi,
I would like to know if there is a way to lock a wallet until a certain date or a block heigh will be reached. ???

For example  I would like to donate to my niece a wallet with some BTCs in but I would like she won't be able to open it before she's 18 years old.

Calculate block number to a certain time should not be an issue taking 10 mins as average time interval. But what about forcing the locked status?
To be feasible,  the method should avoid any future intervention by me so that she will be able to open it anyway even if I would be ( knock on wood :P ) RIP.

Any idea about ?

Tnx

Well probably the same way it is done traditionally. Someone else stores the private key for her, you get the public key.

Yeah I think going via the private key or wallet passphrase would be the way to go. If you don't want a third party involved, maybe use a program that holds the passphrase to unlock the wallet and only gives it away after the given date.

I don't think any wallet software offers such a funtion by default.

could you give me some example?? I googled a bit  but I was not able to find one software like that.

 

I dont think there is one yet, but you can use any software that shows you the private key directly. I assume you will not be able to remember that.

You can create a transaction that cannot be executed until after a specific time or block.

1. Create a transaction that sends bitcoins to an address owned by your niece and include a lock_time value.
2. Give the signed transaction to your niece to hold.
3. After the lock expires, your niece can submit the transaction and it will send the bitcoins to her. If she submits the transaction early, it will be rejected.

Look here: https://en.bitcoin.it/wiki/Protocol_specification#tx and https://en.bitcoin.it/wiki/NLockTime

;D ;D ;D
thank you !!   
that is  exactly what I was looking for . 

You'll have to be careful not to spend the outputs that are used in the LockTime transaction, otherwise that transaction will be invalid when your niece goes to claim it.

She will have to store the transaction somewhere that she can find it when the correct block comes along. If she can't find the transaction, she won't be able to broadcast it.

You'll also both want to keep up with any news about bitcoin in the meantime, since (depending on how long a time period you're talking about) there could theoretically be significant changes to the protocol that render the transaction invalid (in which case you'd need to issue a new transaction).

@DannyHamilton  ,  the "niece"  was just a sample
anyway tnx for the additional info ...  expecially for last one  which I did not consider and  actually the only one that could  be an issue seeing that I cannot control it without a future intervention.
 

You can also look into using https://lbaat.net as LBAAT allows you to store your Bitcoins until a certain point in the future.