How Are People Implementing Their M-of-N (Fragmented) Backup Plan?

[move_zig]

I'm going to switch to Armory and make a paper backup. I don't like the idea of someone who finds my paper backup being able to take all my coins, so I want to implement an m-of-n paper backup plan.

With a 2-of-3 scheme, I plan to store fragments

• in a rented safety deposit box at the bank
• with relatives in another city
• hidden in my house

I could also put a fourth fragment in Google Drive with two-factor authentication, in a 2-of-4 scheme. This would protect me in the event that two fragments get lost. (Yes I know the NSA will be able to read my Google Drive, but they would also have to get another fragment somehow.)


Does anyone have any comments on these plans, or can anyone suggest something better?

[Zomdifros]

My plan is to construct a 2 of 4 backup.

• One paper in my house
• Second one as a digital file, encrypted with TrueCrypt and uploaded to Google Drive (protected by 2FA)
• Third paper with my parents
• Fourth paper attached to my last will

With this scheme I am always able to reconstruct my own wallets without external help, although it's still very hard for anyone to get their hands on more than one backup. I am protected from a fire destroying my house and my family can access my funds in case I die.

[Kyune]

My plan is to construct a 2 of 4 backup.

• One paper in my house
• Second one as a digital file, encrypted with TrueCrypt and uploaded to Google Drive (protected by 2FA)
• Third paper with my parents
• Fourth paper attached to my last will

With this scheme I am always able to reconstruct my own wallets without external help, although it's still very hard for anyone to get their hands on more than one backup. I am protected from a fire destroying my house and my family can access my funds in case I die.

Copies of the last will kept where?

[Zomdifros]

My plan is to construct a 2 of 4 backup.

• One paper in my house
• Second one as a digital file, encrypted with TrueCrypt and uploaded to Google Drive (protected by 2FA)
• Third paper with my parents
• Fourth paper attached to my last will

With this scheme I am always able to reconstruct my own wallets without external help, although it's still very hard for anyone to get their hands on more than one backup. I am protected from a fire destroying my house and my family can access my funds in case I die.

Copies of the last will kept where?

That depends on whether I'm able to get them attached to my last will. If so, they will be stored in the Centraal Testamentregister, a national database in the Netherlands containing every last will. If not, they will be stored at the notary's office in a safe. In any case, a last will is protected by law to be a private document.

[Dabs]

I'm not yet using Armory because I'm waiting for two things: compressed keys, and works on XP. hehehehe.

But this is what I had in mind: compile a list of safe places. To me, these are the following:

1. My house.
2. My parent's house.
3. My in-laws house.
4. Sister's house.
5. Brother's house.
6. Main Office (work).
7. Another office 1. (also work.)
8. Another office 2. (also work.)
9. In the Cloud.

I think that's more than enough, the only problem is all of them are located in the same region and country, except the last one. Those other offices are in different cities, more than a few kilometers away from each other.

So, let's pretend I have 9 locations. N = 9. The debate in my mind now is, how many do I want needed, or M = ? 3? 4? 7 might be too much (and doesn't protect from careless siblings accidentally destroying my little paper backup with them.)

The advantage I have is all the offices have safes or vaults and armed guards and both parent's and in-laws also have a safe or will have one. That, and most of the banks in my area do not offer deposit box services.

[etotheipi]

I'm not yet using Armory because I'm waiting for two things: compressed keys, and works on XP. hehehehe.

But this is what I had in mind: compile a list of safe places. To me, these are the following:

1. My house.
2. My parent's house.
3. My in-laws house.
4. Sister's house.
5. Brother's house.
6. Main Office (work).
7. Another office 1. (also work.)
8. Another office 2. (also work.)
9. In the Cloud.

I think that's more than enough, the only problem is all of them are located in the same region and country, except the last one. Those other offices are in different cities, more than a few kilometers away from each other.

So, let's pretend I have 9 locations. N = 9. The debate in my mind now is, how many do I want needed, or M = ? 3? 4? 7 might be too much (and doesn't protect from careless siblings accidentally destroying my little paper backup with them.)

The advantage I have is all the offices have safes or vaults and armed guards and both parent's and in-laws also have a safe or will have one. That, and most of the banks in my area do not offer deposit box services.

Also, when you are using a high N-value, you can use "privileged" and "unprivileged" holders.  For instance, you might consider your safe-deposit boxes privileged and give them 2 fragments each.  Consider each low-security or low-reliabilty location "unprivileged" and only put one in each.   Certainly the cloud would only get one.

[Dabs]

You can also put one in different clouds. Dunno if that makes any difference. There are so many online backup providers, there are so many free emails (send to yourself as attachments, encrypted or not). I think you only really need to put it on one or two.

[PRab]

I decided to go with 2 of 4 with SecurePrint. I am going to distribute them as follows:

1. At my house.
2. At my parents house.
3. In my safe deposit bank.
4. In the cloud. (No SecurePrint code)

My thought is that the one most likely to get lost/intercepted/stolen is the fragment in the cloud, but because it doesn't have the SecurePrint code with it, it is also the least valuable. I printed the paper backups at a printer at work on a big fancy printer, so in theory, there could still be a copy in there somewhere, but again it doesn't have the SecurePrint code.

[David Rabahy]

I would like to go through the steps of a trial recovery just to be sure.  That would compromise the backups, right?  So, a fresh set of fragments would need to be generated and secured, right?

Is it possible to imagine a trial recovery process that doesn't compromise the backups?

[etotheipi]

Using the backups doesn't compromise them.  Using them on a computer with lower security than plan to keep them is what's dangerous.  If you put the wallet on your offline computer, you can test your backups on that computer no problem.  In fact, when you click "Import or Restore Wallet" in the upper-right of the Armory window, there is an option for "This is a test recovery to make sure my backups work".  If you are fragmenting, you can enter all fragments and Armory will test all subsets of them.  For instance, if you put in 6 fragments and any 3 of them restore the wallet, it will show you the results from computing the restored wallet on all 20 subsets. 

No data is written to disk when you do a restore test, though I still encourage you not to do it on a computer at lower security than where the wallet will be kept. 

Though, I do encourage you, if you just created the wallet and haven't put any money on it yet, to delete the wallet and restore from your backup (using any subset of the fragments).  Sometimes people need to do this to convince themselves their backup will work.