diff --git a/src/main.rs b/src/main.rs
index 92af7f7..29f5a30 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -6,7 +6,7 @@ use axum::{
     Json, Router,
 };
 use clap::Parser;
-use num::{BigInt, Num};
+use num::{BigInt, BigUint, Num};
 use oracle::*;
 use serde::{Deserialize, Serialize};
 use stark_vrf::{generate_public_key, BaseField, StarkVRF};
@@ -19,8 +19,12 @@ use tracing::debug;
 #[command(version, about, long_about = None)]
 struct Args {
     /// Secret key
-    #[arg(short, long, required = true)]
-    secret_key: u64,
+    #[arg(short, long, required = true, help = "Secret key as hex string")]
+    secret_key: String,
+
+    /// Port
+    #[arg(short, long, default_value = "3003")]
+    port: u16,
 }
 
 fn format<T: std::fmt::Display>(v: T) -> String {
@@ -34,14 +38,21 @@ struct InfoResult {
     public_key_y: String,
 }
 
-fn get_secret_key() -> String {
+fn get_secret_key() -> BigUint {
     let args = Args::parse();
-    args.secret_key.to_string()
+    BigUint::from_str_radix(
+        args
+            .secret_key
+            .trim_start_matches("0x")
+            .trim_start_matches("0X"),
+        16,
+    )
+    .expect("unable to parse secret_key")
 }
 
 async fn vrf_info() -> Json<InfoResult> {
     let secret_key = get_secret_key();
-    let public_key = generate_public_key(secret_key.parse().unwrap());
+    let public_key = generate_public_key(secret_key.into());
 
     Json(InfoResult {
         public_key_x: format(public_key.x),
@@ -57,7 +68,7 @@ struct JsonResult {
 async fn stark_vrf(extract::Json(payload): extract::Json<StarkVrfRequest>) -> Json<JsonResult> {
     debug!("received payload {payload:?}");
     let secret_key = get_secret_key();
-    let public_key = generate_public_key(secret_key.parse().unwrap());
+    let public_key = generate_public_key(secret_key.clone().into());
 
     println!("public key {public_key}");
 
@@ -72,9 +83,7 @@ async fn stark_vrf(extract::Json(payload): extract::Json<StarkVrfRequest>) -> Js
         .collect();
 
     let ecvrf = StarkVRF::new(public_key).unwrap();
-    let proof = ecvrf
-        .prove(&secret_key.parse().unwrap(), seed.as_slice())
-        .unwrap();
+    let proof = ecvrf.prove(&secret_key.into(), seed.as_slice()).unwrap();
     let sqrt_ratio_hint = ecvrf.hash_to_sqrt_ratio_hint(seed.as_slice());
     let rnd = ecvrf.proof_to_hash(&proof).unwrap();
 
@@ -100,7 +109,7 @@ async fn stark_vrf(extract::Json(payload): extract::Json<StarkVrfRequest>) -> Js
 
 #[tokio::main(flavor = "current_thread")]
 async fn main() {
-    Args::parse();
+    let args = Args::parse();
 
     tracing_subscriber::fmt()
         .with_max_level(tracing::Level::DEBUG)
@@ -116,11 +125,11 @@ async fn main() {
         .route("/stark_vrf", post(stark_vrf))
         .layer(TraceLayer::new_for_http());
 
-    let listener = tokio::net::TcpListener::bind("0.0.0.0:3000")
+    let listener = tokio::net::TcpListener::bind(format!("0.0.0.0:{}", &args.port))
         .await
-        .expect("Failed to bind to port 3000, port already in use by another process. Change the port or terminate the other process.");
+        .expect(&format!("Failed to bind to port {}, port already in use by another process. Change the port or terminate the other process.", &args.port));
 
-    debug!("Server started on http://0.0.0.0:3000");
+    debug!("Server started on http://0.0.0.0:{}", &args.port);
 
     axum::serve(listener, app)
         .with_graceful_shutdown(shutdown_signal())