1
$\begingroup$

I want to create a file that I could give to 3 trusted friends, and allow any two of them to decrypt it when together (or in sequence when not physically in the same place). This is similar to a multi-signature crypto wallet, but I just want to do it with a file.

The use case is to create a document that would contain my sensitive passwords, bank accounts, life insurance etc... in the event of death or illness. I would give it to three people in advance.

$\endgroup$
4
$\begingroup$

This is precisely the domain of secret sharing, of which there are various popular schemes like Shamir's secret-sharing scheme, and there are many widely available implementations of it in various forms which you can find with exactly those keywords.

$\endgroup$
0
$\begingroup$

If this is for fun, definitely look at Shamir's secret sharing. But if the data is as tiny as it sounds and you want something low tech, you can just do this. Name the three people A, B, C. Create three secret keys, one for each, a, b, c. let m be the password file, e be your favorite encryption program. Give A two files: e(e(m,b),a) and e(e(m,c),a). Give C one file: e(e(m,b),c).

(Optional: let them keep their original names in case they don't like going by "A", "B", or "C". This also results in less paperwork.)

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.