When using Shamir's secret sharing algorithm one has to define the size for the finite field over which the secret is split. I came across a few implementations, like secrets.js-lit, and as far as I can see the implementation chunks the secret that is to be split into 8-bit sized blocks by default.

Is security reduced by chunking a 256-bit secret with 256-bit entropy into smaller blocks, in this case 8-bit, and split the blocks into shares?

My intuition was that this will reduce security because you can brute force through each byte to get the correct share, but when thinking about it for a little longer I came to the conclusion that this is not the case. You don't get validation whether the value you got was the correct one or not, so you need to guess the values of all the other chunks too for the result to validate your guess, thus increasing the brute-force-space to 256-bit again.


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