diff --git a/apub-core/src/signature.rs b/apub-core/src/signature.rs
index 03533bc..bc4a0f6 100644
--- a/apub-core/src/signature.rs
+++ b/apub-core/src/signature.rs
@@ -13,3 +13,15 @@ pub trait SignFactory {
     fn key_id(&self) -> Self::KeyId;
     fn signer(&self) -> Self::Signer;
 }
+
+pub trait Verify {
+    type Error: std::error::Error + Send;
+
+    fn verify(&self, signing_string: &str, signature: &str) -> Result<bool, Self::Error>;
+}
+
+pub trait VerifyFactory {
+    type Verifier: Verify + Send + 'static;
+
+    fn verifier(&self, public_key_pem: String) -> Self::Verifier;
+}