Add verify() to the Signer trait

And implement it for Blog and User

plume-common/src/activity_pub/sign.rs

@@ -20,6 +20,8 @@ pub trait Signer {
     
     /// Sign some data with the signer keypair
     fn sign(&self, to_sign: String) -> Vec<u8>;
+    /// Verify if the signature is valid
+    fn verify(&self, data: String, signature: Vec<u8>) -> bool;
 }
 
 pub trait Signable {

plume-models/src/blogs.rs

@@ -12,7 +12,7 @@ use openssl::{
     hash::MessageDigest,
     pkey::{PKey, Private},
     rsa::Rsa,
-    sign::Signer
+    sign::{Signer,Verifier}
 };
 use webfinger::*;
 
@@ -309,6 +309,13 @@ impl sign::Signer for Blog {
         signer.update(to_sign.as_bytes()).unwrap();
         signer.sign_to_vec().unwrap()
     }
+
+    fn verify(&self, data: String, signature: Vec<u8>) -> bool {
+       let key = PKey::from_rsa(Rsa::public_key_from_pem(self.public_key.as_ref()).unwrap()).unwrap();
+       let mut verifier = Verifier::new(MessageDigest::sha256(), &key).unwrap();
+        verifier.update(data.as_bytes()).unwrap();
+        verifier.verify(&signature).unwrap()
+    }
 }
 
 impl NewBlog {

plume-models/src/users.rs

@@ -604,6 +604,13 @@ impl Signer for User {
         signer.update(to_sign.as_bytes()).unwrap();
         signer.sign_to_vec().unwrap()
     }
+
+    fn verify(&self, data: String, signature: Vec<u8>) -> bool {
+        let key = PKey::from_rsa(Rsa::public_key_from_pem(self.public_key.as_ref()).unwrap()).unwrap();
+       let mut verifier = sign::Verifier::new(MessageDigest::sha256(), &key).unwrap();
+        verifier.update(data.as_bytes()).unwrap();
+        verifier.verify(&signature).unwrap()
+    }
 }
 
 impl NewUser {