Theory and setup
The plan is to setup a plan when your family find out you died, they can recover your crypto. You will need 2 lawyers to setup this plan. But our plan will utilize some cryptography tools so neither your lawyer or your family members can access your crypto not as you intended.
To achieve what we want, we need threshold encryption, where we need to encrypt containers and make sure that we need at least 2 out of the 3 existing keys to open them, we can use veracrypt https://blog.nowhere.moe/opsec/veracrypt/index.html, but instead of only using passwords, we'll use keyfiles
We will setup a container with password and keyfile, for these kind of container you will need both password and keyfile to open, if one of them is lost, it is impossible to decrypt
We will assume you already know to create veracrypt containers and how to mount them
The plan is to achieve a 2/3 multisig scheme. Which means we will have 3 keys, and we should be able to access our wallet with any 2 key. It is like a council with 3 people, but you only need 2 people to agree to pass a law
Monero multi-sig feature is still experimental, and has vulnerability before, so we will use veracrypt to achieve this multi-sig feature. Veracrypt itself does not support multi-sig,so we have to use some little tricks to achieve that. In short, we will create 3 keys and 3 containers.
Let's do a simple math, there is 3 possible combinations for 3 keys
Then you create 3 containers with idential content, but encrypted with 3 keyfile combinations, thus you can achieve a 2/3 multi-sig
Finally you need to thing about a password, since this is also required for veracrypt to operate. You need to remember this, and you should notify your family members about this and make sure they also remember it.
Then use veracrypt to generate 3 keyfiles, keyfiles will be random files generated by veracrypt. They have size of 1024kb and is highly random, so your container is impossible to open without them.
Choose to create a new volume, click next until you see the keyfiles option
We will try to generate 3 random keyfiles
Move your mouse to collect enough entropy, this is very important! The protection from cryptography will be significantly weakened if there is not enough randomness. Then set the key file size to maximum which is 1048576. This is the maximum size utilized by veracrypt and we should use that.
Name your keyfile as key 1 and save it. And repeat this step to produce key 2 and key 3. You shoud have 3 keyfiles now ready for being used to encrypt your containers.
We will then continue to create 3 containers, you will create containers with the same password, but use a different combination of 2 keyfiles for each container as planned
As a remaider, 3 containers will have a encryption setup like this
Volume 1 : password + key file 1 + key file 2
Volume 2 : password + key file 2 + key file 3
Volume 3 : password + key file 1 + key file 3
Add the keyfiles in keyfile option when creating a new volume
You will always save three containers together, this means your family member can unlock 1 of the 3 container even one keyfile is lost.
The last thing to do is to try to unlock your containers, if sucessful, put your seed text file into each container
Prepare your seed and save it in a file, remember to do this in a trusted environment and destroy it later!
Then unlock each container, and make sure you copy the seed into it
Then you need to properly distribute the keyfiles as follows:
1.You will keep key file 1, and the local copies of containers at home
2.Tell your family members about the plan, and most importantly the password they need to know because they still need that for container decryption.
3.Upload the containers to a cloud storage which is controlled by your family members as a backup. You better ask them which cloud service they use, like icloud or gdrive, and copy the containers to their devices and upload to the cloud, so they can easily find the containers through their most familiar method
4.Handle a physical copy of keyfile 2 and keyfile 3 to two different lawyers in different countries, and ask them to send it to your family members when you die officially.
In short there are 6 factors that determine the sucess of inheritance, only the keyfiles allow 1 fault to happen, so you should be really careful and make sure every part work as expected
In this setup your monero can be safely inherited, and it is resistant against accidents. Different things can happen:
1.The best case is you died, your family member grab your local copy of containers and keyfile1, and receive keyfile 2 from one lawyer. Then sucessfully decrypt to get the seed, and recovered your monero
2.Your home is destroyed in a disaster, but your family members and download the containers from the cloud. They wait until both lawyers deliver keyfile 2 and keyfile 3 to them. Then unlocked to recover your monero.
3.One of the lawyer died in earthquake, plus his office also destroyed. Your family member still have your local copy of containers and keyfile 1, and receive another keyfile from the survived lawyer. They unlocked and recovered your monero.
You should find lawyers in different cities to reduce the risk.
You can also print this down as a reference for your family
This plan prevents your lawyers to steal crypto, because they do not have the containers plus the password. Your family members also cannot access your crypto, because they only have one key.
