Add a cautionary assert to share_at_indices to prevent user from misusing the api and passing 0 as index
#157
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MatanHamilis
reviewed
Dec 7, 2021
| @@ -102,14 +102,19 @@ impl<E: Curve> VerifiableSS<E> { | |||
| ) | |||
| } | |||
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| // generate VerifiableSS from a secret and user defined x values (in case user wants to distribute point f(1), f(4), f(6) and not f(1),f(2),f(3)) | |||
| /// generate VerifiableSS from a secret and user defined x values (in case user wants to distribute point f(1), f(4), f(6) and not f(1),f(2),f(3)) | |||
| /// NOTE: The caller should make sure that `t`, `n` and the contents of `index_vec` can't be controlled by a malicious party.. | |||
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Redundant period at EOL.
| pub fn share_at_indices( | ||
| t: u16, | ||
| n: u16, | ||
| secret: &Scalar<E>, | ||
| index_vec: &[u16], | ||
| ) -> (VerifiableSS<E>, SecretShares<E>) { | ||
| assert_eq!(usize::from(n), index_vec.len()); | ||
| assert!( | ||
| !index_vec.iter().any(|&i| i == 0), |
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Perhaps we want the the vector to be of type NonZeroU16?
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Changed to an iterator of NonZeroU16
…ce non zero at the type level
MatanHamilis
approved these changes
Dec 13, 2021
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VerifiableSS::share_at_indicesis meant for users to share a secret atf(0), the caller of this API is required to check that the indexes aren't controlled by an attacker, as an attacker could say that their index is the same as some other party's index, or that it is zero, or even claim that it has multiple indices allowing it to havetpoints by its self.Nonetheless after a report from Trail-Of-Bits we add a cautionary assert to make sure the indices don't contain any zeros, because this is the worst kind of API mistake the user can make (as it tells them the secret)