diff --git a/Cargo.lock b/Cargo.lock
index a1e954d..b4fc428 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1363,6 +1363,7 @@ dependencies = [
  "rand",
  "rcgen",
  "reqwest",
+ "ring",
  "rmp-serde 1.1.1",
  "rustls",
  "rusty_ulid 1.0.0",
diff --git a/crates/ptth_quic/Cargo.toml b/crates/ptth_quic/Cargo.toml
index 2e25ff4..f8bc363 100644
--- a/crates/ptth_quic/Cargo.toml
+++ b/crates/ptth_quic/Cargo.toml
@@ -17,6 +17,7 @@ hyper = { version = "0.14.23", features = ["http1", "server", "stream", "tcp"] }
 quinn = "0.9.3"
 rand = "0.8.5"
 rcgen = "0.10.0"
+ring = "0.16.20"
 rmp-serde = "1.1.1"
 rustls = "0.20.7"
 rusty_ulid = "1.0.0"
diff --git a/crates/ptth_quic/src/crypto.rs b/crates/ptth_quic/src/crypto.rs
new file mode 100644
index 0000000..edfe197
--- /dev/null
+++ b/crates/ptth_quic/src/crypto.rs
@@ -0,0 +1,32 @@
+
+#[cfg (test)]
+mod test {
+	#[test]
+	fn signing () -> anyhow::Result <()> {
+		use std::fs;
+		use ring::{
+			signature::{
+				self,
+				Ed25519KeyPair,
+				KeyPair,
+			},
+		};
+		
+		fs::create_dir_all ("untracked")?;
+		
+		let rng = ring::rand::SystemRandom::new ();
+		let pkcs8_bytes = Ed25519KeyPair::generate_pkcs8 (&rng).map_err (|_| anyhow::anyhow! ("generate_pkcs8"))?;
+		
+		let key_pair = Ed25519KeyPair::from_pkcs8 (pkcs8_bytes.as_ref ()).map_err (|_| anyhow::anyhow! ("from_pkcs8"))?;
+		
+		const MESSAGE: &[u8] = b":V";
+		let sig = key_pair.sign (MESSAGE);
+		
+		let peer_public_key_bytes = key_pair.public_key ().as_ref ();
+		let peer_public_key = signature::UnparsedPublicKey::new (&signature::ED25519, peer_public_key_bytes);
+		
+		peer_public_key.verify (MESSAGE, sig.as_ref ()).map_err (|_| anyhow::anyhow! ("verify"))?;
+		
+		Ok (())
+	}
+}
diff --git a/crates/ptth_quic/src/lib.rs b/crates/ptth_quic/src/lib.rs
index 5cf334c..0d695be 100644
--- a/crates/ptth_quic/src/lib.rs
+++ b/crates/ptth_quic/src/lib.rs
@@ -1,7 +1,11 @@
 pub mod client_proxy;
 pub mod connection;
+pub mod crypto;
 pub mod executable_end_server;
 pub mod executable_relay_server;
 pub mod prelude;
 pub mod protocol;
 pub mod quinn_utils;
+
+#[cfg (test)]
+mod tests;
diff --git a/crates/ptth_quic/src/tests.rs b/crates/ptth_quic/src/tests.rs
new file mode 100644
index 0000000..d110bc6
--- /dev/null
+++ b/crates/ptth_quic/src/tests.rs
@@ -0,0 +1,14 @@
+#[test]
+fn end_to_end () -> anyhow::Result <()> {
+	let rt = tokio::runtime::Runtime::new ()?;
+	rt.block_on (end_to_end_async ())?;
+	Ok (())
+}
+
+async fn end_to_end_async () -> anyhow::Result <()> {
+	
+	
+	// let task_relay = crate::executable_relay_server::main ();
+	
+	Ok (())
+}