Now, here is my solution. I can create a private key using 20 words. And I can make the last 5 words something only I know. I can email my family (and myself) the first 15 words. Then, I can email them the clues of my last 5 words. Of course, I have to do a damn good job that only the ones I fully trust know the answers. So, I guess my method is 3/4 paper - 1/4 brain wallet?
Apart from the risks from your proposal: why would you give your family access to your Bitcoins? If it's meant for the "hit by a bus scenario", there might be another option. I've been thinking about this for a while now, but haven't actually used it:
1. Print a normal paper wallet.
2. Sign a transaction to send funds from your cold storage to the normal paper wallet, but add a
Locktime so it's only valid from a block far far in the future. Say 1 million block count or even more (but not so far none of your family members will still be alive). Or while you're at it: create a few versions (1 million blocks, 1.5 million, 2 million) and print them on different sheets of paper.
3. Print the transaction and store it with the paper wallet.
4. If you're still alive a couple of months before the first transaction becomes valid: burn it, the next one becomes your new fail safe.
If your family ever needs it, all they have to do is wait a few years, broadcast the transaction, and the paper wallet becomes valuable.
Wow
I'll quote this for reference, I'll read it over again, because it seems to be a good solution for this 'bus scenario'
Something else:
Someone mentioned that storing significant amount of bitcoin on hardware wallet is safe enough...
OK, it can be safe, because if the hardware wallet fails, you have your 24 words on a piece of paper packed in a pair of socks in your wardrobe drawer (everyone has them there
)
Now this is where we should hold on for a minute.
If we have the 24 word seed (which you need to restore the hardware wallet) written on that piece of paper laying somewhere, the security of the hardware wallet equals to the security of the method you store your paper wallet... because if someone finds that piece of paper, he/she can restore the hardware wallet and can spend the bitcoins, without the need to physically access your original hardware wallet.
So in my opinion, hardware wallet is OK for a little amount, but for a larger amount, you should think it over again...