improvement: event signature validation is 100x faster

Switched to latest (git) release of secp256k1, which has more
efficient verification-only context for Schnorr.  Switched to single
pre-instantiated instance of the verifier.

src/event.rs

@@ -3,14 +3,19 @@ use crate::config;
 use crate::error::Error::*;
 use crate::error::Result;
 use bitcoin_hashes::{sha256, Hash};
+use lazy_static::lazy_static;
 use log::*;
-use secp256k1::{schnorrsig, Secp256k1};
+use secp256k1::{schnorr, Secp256k1, VerifyOnly, XOnlyPublicKey};
 use serde::{Deserialize, Deserializer, Serialize};
 use serde_json::value::Value;
 use serde_json::Number;
 use std::str::FromStr;
 use std::time::SystemTime;
 
+lazy_static! {
+    pub static ref SECP: Secp256k1<VerifyOnly> = Secp256k1::verification_only();
+}
+
 /// Event command in network format
 #[derive(Serialize, Deserialize, PartialEq, Debug, Clone)]
 pub struct EventCmd {
@@ -109,12 +114,15 @@ impl Event {
             return false;
         }
         // * validate the message digest (sig) using the pubkey & computed sha256 message hash.
-        let secp = Secp256k1::new();
-        let sig = schnorrsig::Signature::from_str(&self.sig).unwrap();
-        let message = secp256k1::Message::from(digest);
-        let pubkey = schnorrsig::PublicKey::from_str(&self.pubkey).unwrap();
-        let verify = secp.schnorrsig_verify(&sig, &message, &pubkey);
-        matches!(verify, Ok(()))
+        let sig = schnorr::Signature::from_str(&self.sig).unwrap();
+        if let Ok(msg) = secp256k1::Message::from_slice(digest.as_ref()) {
+            let pubkey = XOnlyPublicKey::from_str(&self.pubkey).unwrap();
+            let verify = SECP.verify_schnorr(&sig, &msg, &pubkey);
+            matches!(verify, Ok(()))
+        } else {
+            warn!("Error converting digest to secp256k1 message");
+            false
+        }
     }
 
     /// Convert event to canonical representation for signing.

src/main.rs

@@ -98,9 +98,9 @@ async fn handle_web_request(
         }
         ("/", false) => {
             // handle request at root with no upgrade header
-            Ok(Response::new(Body::from(format!(
-                "This is a Nostr relay.\n"
-            ))))
+            Ok(Response::new(Body::from(
+                "This is a Nostr relay.\n".to_string(),
+            )))
         }
         (_, _) => {
             //handle any other url