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I want to protect a seed phrase - a list of 24 words.

I know of Shamir's secret sharing algorithm, but this algorithm only works for integers.

Is there any option to use it for strings rather than integers?

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Two obvious methods:

  • Turn the strings into integers. For example, turn each character into a byte (integer between 0 and 255) and secret share each such byte individually. You could alternatively convert the entire seed phrase into one large bignum, and secret share that (but the resulting bignum math may be a bit annoying...)

  • Pick a random symmetric key (e.g. an AES key), secret share that, and then encrypt the seed phrase with that key.

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    $\begingroup$ The second method stops the secret sharing from being information theoretically secure (which is a property of Shamir's algorithm). $\endgroup$ Commented Apr 3 at 17:33
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    $\begingroup$ @CommandMaster: itamar asked for a way to "protect" his seed phrases - are you claiming that the second method is insecure (or otherwise does not adequately protect his information)? $\endgroup$
    – poncho
    Commented Apr 5 at 15:17
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    $\begingroup$ As for "information theoretically secure": Then again, what the seed phrase is used for is probably also not information theoretically secure, and the practical security of AES is currently not under debate. $\endgroup$
    – Maarten Bodewes
    Commented Apr 5 at 15:17
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    $\begingroup$ @poncho I think that the statement that it removes this property from the secret sharing algorithm is correct in its own right. I don't see Command Master making any claims with regard to the practical implications. It's fine to indicate this in a comment (which I tried to do), but please leave it at that. $\endgroup$
    – Maarten Bodewes
    Commented Apr 5 at 15:20

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