Time-locking money from myself

[josh_the_robot_elf]

Hello ya'll. I just turned 39 and I would like to put some money away for my 40th birthday. If I do this the traditional way, through a safety deposit box or depositing in a bank savings account, I will surely find some cool thing to buy before my birthday and I will withdraw the money and spend it.

I want something as secure and robust as a time-locked bitcoin wallet that can't possibly allow me to spend the funds in it until May 20 2017. It is important that I am also able to make deposits into the wallet until that time.

I have no idea how to do this. I am familiar with bitcoin paper wallets and hot wallets, and I know a bit of python. Are there any hot wallets with this feature, or is there any general know-how for a scripted solution?

I would also like to use this method to create a retirement fund for myself. I do not have a 401K and I like the idea of a sovereign individual's foolproof retirement fund.

[arnoudk]

To do this, you could do the following.

Create an address that will contain the future spendable coins (address A). Save the private key in a secure place. Make backups.
Create a temporary address (address B), make sure to save the private key.
Send some money to this temporary address B.
Create a transaction FROM that temporary address B TO address A, using a time lock in the transaction.
Sign this transaction using the private key of address B.
Store this transaction in a very safe place. Make backups.
Forget private key B. This is dangerous, and not recommended, but it ensures you cannot possibly spend the coins before the future date.
Once the timelock has passed, your transaction becomes spendable. You can submit it to the network, and it will be available for spending once it has confirmed.

Some caveats:
Always test this process and your setup with a few dollars worth of bitcoins - nothing you cannot afford to lose. Make sure you KNOW that it works.
Once you forgot the private key of B, you cannot possibly reuse address B. Any funds sent to it are LOST.
To send more money to future address A, you must create a new temporary address (B2), and repeat the process.
You don't know what fee to attach for a transaction that takes place one year from now. If you do not have enough fee, your transaction may not confirm and you cannot access the funds. There are no child pays for parent options yet, and RBF will not be available if you do not have the private key B. This is a risk you must be willing to accept. You could lose access to your funds here.

My advise is to wait until CHECKLOCKTIMEVERIFY is implemented. That allows an address to be locked until a future time, and appears to offer what you are looking for. It is currently not yet available (soon-ish, hopefully).

[josh_the_robot_elf]

Thanks arnoudk. I want something robust, so I will wait for CHECKLOCKTIMEVERIFY. Thank you very much.

[josh_the_robot_elf]

I did some more research and it looks like CHECKLOCKTIMEVERIFY is already implemented and in use. https://coinb.in/#newTimeLocked https://www.reddit.com/r/Bitcoin/commen ... f_in_2020/

[arnoudk]

Wow, I did not realize it was implemented. Do all miners (the supermajority at least) recognize this opcode on the bitcoin main chain? I will research this a bit more and play around with it on the testnet (and with small amounts on the main network) later.

This is great news. Thanks for sharing the results of your research.

[bitkilo]

Wow, I did not realize it was implemented. Do all miners (the supermajority at least) recognize this opcode on the bitcoin main chain? I will research this a bit more and play around with it on the testnet (and with small amounts on the main network) later.

This is great news. Thanks for sharing the results of your research.

Keep us updated on the tests you do, this would be a useful feature that i didn't know about till now.