chore: adding example for fetching a signature and using it in rust

examples/signature_request.rs

@@ -0,0 +1,35 @@
+use cerberus_api::{
+    client::SignerClient,
+    SignGenericRequest,
+    SignGenericResponse,
+};
+use ark_bn254::{Fq,g1::G1Affine};
+use ark_ff::PrimeField;
+use eigen_crypto_bls::BlsG1Point;
+#[tokio::main]
+async fn main() -> Result<(),Box<dyn std::error::Error>> {
+    let mut client: SignerClient<tonic::transport::Channel> = SignerClient::connect("http://[::1]:50051").await?;
+    let message = "Hello, world!";
+    let message_bytes = message.as_bytes();
+    let request = tonic::Request::new(SignGenericRequest {
+      public_key: "bls_public_key".to_string(),
+      data: message_bytes.to_vec(),
+      password: "password".to_string(),
+    });
+    let response: tonic::Response<SignGenericResponse> = client.sign_generic(request).await?;
+    let g1_affine = response_to_g1_affine(response.into_inner())?;
+    let bls_g1_point = BlsG1Point::new(g1_affine);
+    println!("bls_g1_point={:?}", bls_g1_point);
+    Ok(())
+}
+
+fn response_to_g1_affine(response: SignGenericResponse) -> Result<G1Affine, Box<dyn std::error::Error>> {
+    let signature_bytes = response.signature.clone();
+    let hex_string = hex::encode(&signature_bytes);
+    let bytes = hex::decode(&hex_string).expect("Failed to decode hex");
+    let x_bytes = &bytes[0..32];
+    let y_bytes = &bytes[32..64];
+    let fqx = Fq::from_be_bytes_mod_order(x_bytes);
+    let fqy = Fq::from_be_bytes_mod_order(y_bytes);
+    Ok(G1Affine::new(fqx, fqy))
+}