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diff --git a/vendor/signature/src/verifier.rs b/vendor/signature/src/verifier.rs
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+//! Trait for verifying digital signatures
+
+use crate::error::Error;
+
+#[cfg(feature = "digest")]
+use crate::digest::Digest;
+
+/// Verify the provided message bytestring using `Self` (e.g. a public key)
+pub trait Verifier<S> {
+    /// 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")]
+pub trait DigestVerifier<D: Digest, S> {
+    /// Verify the signature against the given [`Digest`] output.
+    fn verify_digest(&self, digest: D, signature: &S) -> Result<(), Error>;
+}