shards … as in a piece of a whole.
Both terms mean effectively the same thing in context, and are only one letter apart, so it is likely people started accidentally using both.
Looking at the number of Google search hits for “shamir’s secret sharing shares” vs. “shamir’s secret sharing shards”, and considering the name of the algorithm, I disagree with @aram and believe “shares” is probably the original term.
It would be necessary to find a citation of Shamir’s original work to conclusively say one is more correct.
this makes sense to me also, probably need an updation in vault documentation.
It turns out that in Shamir’s original work - whch can be found at https://dl.acm.org/doi/10.1145/359168.359176 - the term used is “pieces”, so I guess both “shares” and “shards” are names that someone came up with later.
As the original author used neither, I guess it is open for discussion which is the better term.
I would lean towards “shares”, as the algorithm includes “Sharing” in its name, and when something is broken in to shards it suggests you need all the shards to reconstruct the whole, which is not the case here. Also the options and help of
vault operator init speak of “shares” already, and the Google hits are greater for “shares” than “shards”.