Topic: Mixin Safe: A Convenient and Decentralized Multisig + MPC + Timelock solution - page 8. (Read 1843 times)

It is not a mixer, it's code for making a multisig transaction where some members cannot spend from it by signing using their keys until after a fixed time period.

But this last link from the OP looks like it's a service that is trying to replace crypto custodials for companies (think Coinbase holding coins for Blackrock), not intended for the general public - I mean how can you say a timelocked multisig is more secure than a hardware wallet, for example?

I am trying to understand, is it a bitcoin mixing service or you are talking about a wallet, perhaps an online wallet?

In case it's a wallet then isn't it means there is this fake sense of decentralization? After all you hold the key and your clients are trusting you with their funds.

Sorry, If I got the whole idea wrong.

I would love to see the finished product first. Then you can start with a review campaign to see the response from the community. I can help you in that if you want.

I had the idea of making a easy to use Bitcoin multisig wallet with timelocked recovery key for a long time, and thanks to the recent development of miniscript in Bitcoin community, I'm able to produce a solution and product that allows the general public to use these advanced features in a very convenient way.

Technology

The underline miniscript of the solution is discussed in another topic https://bitcointalksearch.org/topic/p2wsh-multisig-and-timelock-question-5441806


The miniscript above produces a 2-of-3 multisig, with a 90 days timelock for the RECOVERY key.

For any UTXO created within 90 days, both the OWNER and MEMBERS key must sign the transaction to spend the coins. But after 90 days, the RECOVERY key can step in to work together with either the OWNER or MEMBERS key to spend the coins.


Product

Based on the miniscript technology above, we created a product, Mixin Safe, to make all those steps convenient for Bitcoin holders.

Whenever a new Mixin Safe is created, the Bitcoin holder needs to provide the OWNER public key. To do this, a miniscript compatible wallet is required, we have tested Bitcoin Core and Ledger, and noticed upcoming miniscript support announcements from other hardware vendors, e.g.

• Coldcard https://github.com/Coldcard/firmware/pull/227
• BitBox02 https://twitter.com/_benma_/status/1670022585461907456
• SeedSigner https://twitter.com/pythcoiner/status/1670458117983805442

Then the Bitcoin holder needs to use our another product Mixin Messenger to produce a MPC public key as the MEMBERS key. Although it's possible to generate this MEMBERS key only by yourself, we recommend to choose at least two Mixin Messenger devices, better with your partner, so the MPC key is generated as a 1-of-2 threshold ECDSA key.

Mixin Messenger is an open source MPC wallet for 6 years https://github.com/MixinNetwork/android-app, and the MPC code we used is from https://github.com/taurusgroup/multi-party-sig

Finally, we the Mixin Safe service maintainer holds the RECOVERY key for emergency recovery usage once the OWNER key is lost.


Security

The solution is based on Bitcoin multisig script with timelock, and the recovery key timelock can be adjusted when the wallet is created.

The OWNER key is managed by third party and popular bitcoin wallets,  can have a normal backup solution, and no need to worry about it's stolen or lost. Because nobody will be able to spend the coins with this only OWNER key, and the coins can be recovered even if the OWNER key is completely lost.

The MEMBERS key is managed by open source MPC solution. If MEMBERS key is managed by a few people in 1-of-2 or 3-of-5 or even 5-of-10, it's almost impossible to lose the MEMBERS key.


Try It!

Now the product is generally available, it's a website which is designed to have intuitive interface to use.

https://safe.mixin.one/

Thank you, and welcome suggestions.