diff --git a/src/x509.rs b/src/x509.rs
index 2ea9f54..dee722a 100644
--- a/src/x509.rs
+++ b/src/x509.rs
@@ -6,6 +6,7 @@ use std::str::FromStr;
 use rust_util::XResult;
 use x509_parser::der_parser::der::parse_der_bitstring;
 use x509_parser::der_parser::parse_der;
+use x509_parser::x509::AlgorithmIdentifier;
 
 lazy_static! {
     static ref OID_COMMON_NAME: Oid<'static> = Oid::from_str("2.5.4.3").unwrap();
@@ -13,6 +14,7 @@ lazy_static! {
     static ref OID_ECDSA_WITH_SHA256: Oid<'static> = Oid::from_str("1.2.840.10045.4.3.2").unwrap();
 
     static ref OID_EC_PUBLIC_KEY: Oid<'static> = Oid::from_str("1.2.840.10045.2.1").unwrap();
+    static ref OID_RSA_PUBLIC_KEY: Oid<'static> = Oid::from_str("1.2.840.113549.1.1.11").unwrap();
 
     static ref OID_SECP256R1: Oid<'static> = Oid::from_str("1.2.840.10045.3.1.7").unwrap();
     static ref OID_SECP384R1: Oid<'static> = Oid::from_str("1.3.132.0.34").unwrap();
@@ -25,14 +27,44 @@ pub enum X509IssuerAlgo {
     EcdsaWithSha256,
 }
 
+#[derive(Debug, Clone)]
 pub enum X509EcPublicKeyAlgo {
     Secp256r1,
     Secp384r1,
     Secp521r1,
 }
 
+#[derive(Debug, Clone)]
 pub enum X509PublicKeyAlgo {
-    EcKey(X509EcPublicKeyAlgo)
+    EcKey(X509EcPublicKeyAlgo),
+    Rsa,
+}
+
+impl X509PublicKeyAlgo {
+    pub fn parse<'a>(pem_id: &str, algorithm: &AlgorithmIdentifier<'a>) -> XResult<Self> {
+        let public_key_algo_oid = &algorithm.algorithm;
+        if public_key_algo_oid == &*OID_EC_PUBLIC_KEY {
+            let parameters = match &algorithm.parameters {
+                None => return simple_error!("Cannot find ec public key parameters: {}", pem_id),
+                Some(parameters) => parameters,
+            };
+            let ec_public_key_algo_oid = opt_result!(parameters.content.as_oid(), "Parse public algo: {}, failed: {}", pem_id);
+            let ec_public_key_algo = if ec_public_key_algo_oid == &*OID_SECP256R1 {
+                X509EcPublicKeyAlgo::Secp256r1
+            } else if ec_public_key_algo_oid == &*OID_SECP384R1 {
+                X509EcPublicKeyAlgo::Secp384r1
+            } else if ec_public_key_algo_oid == &*OID_SECP521R1 {
+                X509EcPublicKeyAlgo::Secp521r1
+            } else {
+                return simple_error!("Parse : {}, unknown ec public key algo: {:?}", pem_id, ec_public_key_algo_oid);
+            };
+            Ok(Self::EcKey(ec_public_key_algo))
+        } else if public_key_algo_oid == &*OID_RSA_PUBLIC_KEY {
+            Ok(Self::Rsa)
+        } else {
+            simple_error!("Parse cert: {}, unknown public key algo oid: {}", pem_id, public_key_algo_oid)
+        }
+    }
 }
 
 #[derive(Debug, Clone)]
@@ -40,6 +72,7 @@ pub struct X509Certificate {
     pub issuer_algo: X509IssuerAlgo,
     pub common_name: String,
     pub alt_names: Vec<String>,
+    pub public_key_algo: X509PublicKeyAlgo,
 }
 
 pub fn parse_x500(pem_id: &str, pem: &str) -> XResult<X509Certificate> {
@@ -75,33 +108,12 @@ pub fn parse_x500(pem_id: &str, pem: &str) -> XResult<X509Certificate> {
             }
         }
     }
-    let public_key_algo_oid = &cert.tbs_certificate.subject_pki.algorithm.algorithm;
-    let public_key_algo = if public_key_algo_oid == &*OID_EC_PUBLIC_KEY {
-        // TODO ...
-        let ec_public_key_algo_oid = cert.tbs_certificate.subject_pki.algorithm.parameters.unwrap().content.as_oid().unwrap();
-    };
-
+    let public_key_algo = X509PublicKeyAlgo::parse(pem_id, &cert.tbs_certificate.subject_pki.algorithm)?;
 
     Ok(X509Certificate {
         issuer_algo,
         common_name,
         alt_names,
+        public_key_algo,
     })
 }
-
-#[test]
-fn test_x509() {
-    let pem = include_str!("sample_cert2.pem");
-    let (_, parsed_pem) = parse_x509_pem(pem.as_bytes()).unwrap();
-    let (_, cert) = parse_x509_certificate(parsed_pem.contents.as_slice()).unwrap();
-
-    println!("{:#?}", parse_x500("id", pem));
-
-    println!("{:?}", cert.tbs_certificate.signature);
-    println!("{:?}", cert.tbs_certificate.subject_pki);
-    println!("{:?}", cert.tbs_certificate.subject_pki.algorithm.algorithm);
-    println!("{:?}", cert.tbs_certificate.subject_pki.algorithm.parameters.unwrap().content.as_oid().unwrap());
-
-    let a = parse_der(cert.tbs_certificate.subject_pki.subject_public_key.data);
-    println!("{:?}", a);
-}
\ No newline at end of file