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//! Trait for verifying digital signatures use crate::{error::Error, Signature}; #[cfg(feature = "digest-preview")] use crate::digest::Digest; /// Verify the provided message bytestring using `Self` (e.g. a public key) pub trait Verifier<S: Signature> { /// Use `Self` to verify that the provided signature for a given message /// bytestring is authentic. /// /// Returns `Error` if it is inauthentic, or otherwise returns `()`. fn verify(&self, msg: &[u8], signature: &S) -> Result<(), Error>; } /// Verify the provided signature for the given prehashed message [`Digest`] /// is authentic. /// /// ## Notes /// /// This trait is primarily intended for signature algorithms based on the /// [Fiat-Shamir heuristic], a method for converting an interactive /// challenge/response-based proof-of-knowledge protocol into an offline /// digital signature through the use of a random oracle, i.e. a digest /// function. /// /// The security of such protocols critically rests upon the inability of /// an attacker to solve for the output of the random oracle, as generally /// otherwise such signature algorithms are a system of linear equations and /// therefore doing so would allow the attacker to trivially forge signatures. /// /// To prevent misuse which would potentially allow this to be possible, this /// API accepts a [`Digest`] instance, rather than a raw digest value. /// /// [Fiat-Shamir heuristic]: https://en.wikipedia.org/wiki/Fiat%E2%80%93Shamir_heuristic #[cfg(feature = "digest-preview")] #[cfg_attr(docsrs, doc(cfg(feature = "digest-preview")))] pub trait DigestVerifier<D, S> where D: Digest, S: Signature, { /// Verify the signature against the given [`Digest`] output. fn verify_digest(&self, digest: D, signature: &S) -> Result<(), Error>; }