diff --git a/__enclave/virt_enclave/Cargo.lock b/__enclave/virt_enclave/Cargo.lock
index afbb94d..bd52537 100644
--- a/__enclave/virt_enclave/Cargo.lock
+++ b/__enclave/virt_enclave/Cargo.lock
@@ -1,11 +1,52 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+[[package]]
+name = "arrayref"
+version = "0.3.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a4c527152e37cf757a3f78aae5a06fbeefdb07ccc535c980a3208ee3060dd544"
+
+[[package]]
+name = "arrayvec"
+version = "0.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "23b62fc65de8e4e7f52534fb52b0f3ed04746ae267519eef2a83941e8085068b"
+
+[[package]]
+name = "autocfg"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cdb031dd78e28731d87d56cc8ffef4a8f36ca26c38fe2de700543e627f8a464a"
+
+[[package]]
+name = "base64"
+version = "0.12.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3441f0f7b02788e948e47f457ca01f1d7e6d92c693bc132c22b087d3141c03ff"
+
+[[package]]
+name = "blake2b_simd"
+version = "0.5.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "afa748e348ad3be8263be728124b24a24f268266f6f5d58af9d75f6a40b5c587"
+dependencies = [
+ "arrayref",
+ "arrayvec",
+ "constant_time_eq",
+]
+
 [[package]]
 name = "bumpalo"
 version = "3.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2e8c087f005730276d1096a652e92a8bacee2e2472bcc9715a74d2bec38b5820"
 
+[[package]]
+name = "byteorder"
+version = "1.3.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "08c48aae112d48ed9f069b33538ea9e3e90aa263cfa3d1c24309612b1f7472de"
+
 [[package]]
 name = "cc"
 version = "1.0.61"
@@ -18,6 +59,45 @@ version = "0.1.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
 
+[[package]]
+name = "constant_time_eq"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "245097e9a4535ee1e3e3931fcfcd55a796a44c643e8596ff6566d68f09b87bbc"
+
+[[package]]
+name = "crossbeam-utils"
+version = "0.7.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c3c7c73a2d1e9fc0886a08b93e98eb643461230d5f1925e4036204d5f2e261a8"
+dependencies = [
+ "autocfg",
+ "cfg-if",
+ "lazy_static",
+]
+
+[[package]]
+name = "dirs"
+version = "1.0.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3fd78930633bd1c6e35c4b42b1df7b0cbc6bc191146e512bb3bedf243fcc3901"
+dependencies = [
+ "libc",
+ "redox_users",
+ "winapi",
+]
+
+[[package]]
+name = "getrandom"
+version = "0.1.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fc587bc0ec293155d5bfa6b9891ec18a1e330c234f896ea47fbada4cadbe47e6"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi",
+]
+
 [[package]]
 name = "hex"
 version = "0.4.2"
@@ -84,6 +164,23 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "redox_syscall"
+version = "0.1.57"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "41cc0f7e4d5d4544e8861606a285bb08d3e70712ccc7d2b84d7c0ccfaf4b05ce"
+
+[[package]]
+name = "redox_users"
+version = "0.3.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "de0737333e7a9502c789a36d7c7fa6092a49895d4faa31ca5df163857ded2e9d"
+dependencies = [
+ "getrandom",
+ "redox_syscall",
+ "rust-argon2",
+]
+
 [[package]]
 name = "ring"
 version = "0.16.15"
@@ -99,6 +196,30 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "rust-argon2"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9dab61250775933275e84053ac235621dfb739556d5c54a2f2e9313b7cf43a19"
+dependencies = [
+ "base64",
+ "blake2b_simd",
+ "constant_time_eq",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "rust_util"
+version = "0.6.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "754278eaff41b86ced9e2913b3f5ee8bd7c2446be81f0739a567e9d0ad6cdb3a"
+dependencies = [
+ "lazy_static",
+ "libc",
+ "term",
+ "term_size",
+]
+
 [[package]]
 name = "ryu"
 version = "1.0.5"
@@ -153,6 +274,27 @@ dependencies = [
  "unicode-xid",
 ]
 
+[[package]]
+name = "term"
+version = "0.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "edd106a334b7657c10b7c540a0106114feadeb4dc314513e97df481d5d966f42"
+dependencies = [
+ "byteorder",
+ "dirs",
+ "winapi",
+]
+
+[[package]]
+name = "term_size"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e4129646ca0ed8f45d09b929036bafad5377103edd06e50bf574b353d2b08d9"
+dependencies = [
+ "libc",
+ "winapi",
+]
+
 [[package]]
 name = "unicode-xid"
 version = "0.2.1"
@@ -171,10 +313,17 @@ version = "0.1.0"
 dependencies = [
  "hex",
  "ring",
+ "rust_util",
  "serde",
  "serde_json",
 ]
 
+[[package]]
+name = "wasi"
+version = "0.9.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cccddf32554fecc6acb585f82a32a72e28b48f8c4c1883ddfeeeaa96f7d8e519"
+
 [[package]]
 name = "wasm-bindgen"
 version = "0.2.68"
diff --git a/__enclave/virt_enclave/Cargo.toml b/__enclave/virt_enclave/Cargo.toml
index 055e27b..a5d73b6 100644
--- a/__enclave/virt_enclave/Cargo.toml
+++ b/__enclave/virt_enclave/Cargo.toml
@@ -7,7 +7,8 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-ring = "0.16.13"
-hex = "0.4.2"
+ring = "0.16"
+hex = "0.4"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
+rust_util = "0.6"
diff --git a/__enclave/virt_enclave/src/sig.rs b/__enclave/virt_enclave/src/sig.rs
index 128dbc3..aa6c2ae 100644
--- a/__enclave/virt_enclave/src/sig.rs
+++ b/__enclave/virt_enclave/src/sig.rs
@@ -1,9 +1,14 @@
+use std::fs::File;
+use std::io::{ Write, Read };
+use serde::{ Deserialize, Serialize };
 use ring::{
     signature::{ KeyPair, Ed25519KeyPair, UnparsedPublicKey, ED25519 },
     hmac, rand, error::Unspecified,
     digest,
 };
+use rust_util::XResult;
 
+#[derive(Serialize, Deserialize)]
 pub struct SigningKeyPair {
     key_pair: Vec<u8>,
 }
@@ -20,22 +25,92 @@ impl SigningKeyPair {
     fn parse(&self) -> Ed25519KeyPair {
         Ed25519KeyPair::from_pkcs8(&self.key_pair).unwrap() // TODO ...
     }
+
+    fn public_key(&self) -> Vec<u8> {
+        self.parse().public_key().as_ref().to_vec()
+    }
+
+    fn unparsed_public_key(&self) -> UnparsedPublicKey<Vec<u8>> {
+        UnparsedPublicKey::new(&ED25519, self.public_key())
+    }
+
+    fn read_from_file(file: &str) -> XResult<Self> {
+        match File::open(file) {
+            Err(e) => Err(rust_util::new_box_ioerror(&format!("Read from file failed: {}", e))),
+            Ok(mut f) => {
+                let mut buf = String::new();
+                match f.read_to_string(&mut buf) {
+                    Err(e) => Err(rust_util::new_box_ioerror(&format!("Read from file failed: {}", e))),
+                    Ok(_) => {
+                        let kp: Self = match serde_json::from_str(&buf) {
+                            Err(e) => return Err(rust_util::new_box_ioerror(&format!("Parse JSON failed: {}", e))),
+                            Ok(k) => k,
+                        };
+                        Ok(kp)
+                    }
+                }
+            },
+        }
+    }
+
+    fn write_to_file(&self, file: &str) -> XResult<()> {
+        if File::open(file).is_ok() {
+            return Err(rust_util::new_box_ioerror(&format!("File exists: {}", file)));
+        }
+        let ser_bytes = match serde_json::to_string_pretty(self) {
+            Err(e) => return  Err(rust_util::new_box_ioerror(&format!("Serilize key pair failed: {}", e))),
+            Ok(s) => s,
+        };
+        match File::create(file) {
+            Err(e) => return Err(rust_util::new_box_ioerror(&format!("File create: {}, failed: {}", file, e))),
+            Ok(mut f) => {
+                match f.write_all(ser_bytes.as_bytes()) {
+                    Err(e) => Err(rust_util::new_box_ioerror(&format!("File create: {}, failed: {}", file, e))),
+                    Ok(_) => Ok(()),
+                }
+            },
+        }
+    }
 }
 
+#[derive(Serialize, Deserialize)]
 pub struct SignedMessage {
     msg: Vec<u8>,
-    sig: Vec<u8>,
-    desc: String,
+    sig: Option<Vec<u8>>,
+    desc: Option<String>,
 }
 
 impl SignedMessage {
-    pub fn sign(key_pair: &Ed25519KeyPair, msg: &[u8]) -> Vec<u8> {
-        let sig = key_pair.sign(msg);
-        sig.as_ref().to_vec()
+    pub fn new(msg: Vec<u8>, desc: Option<String>) -> Self {
+        Self {
+            msg,
+            sig: None,
+            desc,
+        }
+    }
+
+    pub fn sign(&mut self, key_pair: &SigningKeyPair) {
+        let sig = key_pair.parse().sign(&self.msg);
+        self.sig = Some(sig.as_ref().to_vec());
     }
 
     pub fn verify(&self, public_key: &[u8]) -> bool {
-        let verify_result = UnparsedPublicKey::new(&ED25519, &public_key).verify(&self.msg, &self.sig);
-        verify_result.is_ok()
+        match &self.sig {
+            None => false,
+            Some(sig) => {
+                let verify_result = UnparsedPublicKey::new(&ED25519, &public_key).verify(&self.msg, sig);
+                verify_result.is_ok()
+            }
+        }
     }
+}
+
+#[test]
+fn test_sign() {
+    let signing_key_pair = SigningKeyPair::new();
+    let mut signed_message = SignedMessage::new(
+        "Hello".as_bytes().to_vec(), Some("DESC".to_owned())
+    );
+    signed_message.sign(&signing_key_pair);
+    assert!(signed_message.verify(&signing_key_pair.public_key()))
 }
\ No newline at end of file