Add signature basics

Add a way to sign and verify keys. Still need to figure out the
keyserver situation and how to make that shit work

src/client.rs

@@ -1,9 +1,13 @@
 use uuid::Uuid;
-use crate::message::{MessageId,TaggedMessage,VerificationError,Relevance};
+use crate::message::{MessageId,TaggedMessage,Relevance};
 use crate::state::{self,StateValue,StatePath,StatePermission,StatePermissionKey};
 use crate::{RoomId,Group,Role,User,GroupPower,ServerAddr};
+use ed25519::signature::{Signer,Verifier};
+use ed25519::Signature;
+use rmp_serde::encode::Serializer;
 use serde::{Deserialize, Serialize};
 use time::OffsetDateTime;
+use thiserror::Error;
 
 //StatePath [String]
 //octal is fine for now
@@ -61,9 +65,38 @@ impl SignedClientMessage {
             target: self.target.unwrap_or(servername)
         }
     }
-    pub fn verify(&self) -> Result<bool,VerificationError> {
-        unimplemented!()
+    // Canonical way to sign messages. Glue the message, target, and timestamp together. Serialize
+    // them, then sign those bytes. It is slightly ambiguous how target=None messages should
+    // by signed vs target=Some(local_server) especially if rewriting of the target happens.
+    // This makes signature verification harder as you would have to check both
+    // cases to see if either correctly verifies.
+    pub fn sign<S: Signer<ed25519::Signature>>(&mut self, signer: S) -> Result<(),SignatureError> {
+
+        let mut bytes = Vec::new();
+        (&self.message,&self.target,&self.timestamp).serialize(&mut Serializer::new(&mut bytes).with_struct_map())?;
+        let result = signer.try_sign(&bytes)?;
+                
+
+        self.signature = Box::new(result.to_bytes());
+        Ok(())
     }
+    pub fn verify<V: Verifier<ed25519::Signature>>(&self, verifier: V) -> Result<(),SignatureError> {
+
+        let mut bytes = Vec::new();
+        (&self.message,&self.target,&self.timestamp).serialize(&mut Serializer::new(&mut bytes).with_struct_map())?;
+        
+
+        let sig = Signature::from_slice(&self.signature)?;
+        Ok(verifier.verify(&bytes,&sig)?)
+    }
+}
+
+#[derive(Debug,Error)]
+pub enum SignatureError {
+    #[error("Problem while making eliptic curve {0}")]
+    Ed25519(#[from] ed25519::Error),
+    #[error("Serialization error: {0}")]
+    Serialization(#[from] rmp_serde::encode::Error),
 }
 #[derive(Serialize,Deserialize,Clone,Debug)]
 pub enum AuthMethod {