（时间都去哪儿了）去年一整年都没看mixin相关的开发内容了。最近东哥小米圈看到 [Mixin Safe](https://safe.mixin.dev/) 发布，正好跟着练练手。

首先要了解以下概念——

Mixin Safe uses the native Bitcoin multisig and timelock script as a state-of-the-art solution to secure BTC. The 2/3 multisig is composed of three keys, holder, signer and observer. With a timelock of 1 year, if and only if holder and signer both sign the transaction, the BTC can be spent. In any case of holder or signer key lost, the observer can be the rescuer after 1 year.

Specifically, the signer key is MPC generated by Mixin Safe nodes, so it's decentralized controlled. Whenever a deposit detected to a safe account, Mixin Safe will issue the same amount of safeBTC to the account owner. To make the signer key sign a transaction with the holder, the account owner needs to send safeBTC to the safe network, and sign the raw transaction with the holder key.