feat: add examples

__enclave/virt_enclave/examples/create_signing_key.rs

@@ -0,0 +1,9 @@
+use virt_enclave::sig::SigningKeyPair;
+
+fn main() {
+    let signing_key_pair = SigningKeyPair::new();
+    match signing_key_pair.write_to_file("platform_signing_key.json") {
+        Err(_) => println!("Write platform signing key failed!"),
+        Ok(_) => println!("Write platform signing key successed!"),
+    }
+}

__enclave/virt_enclave/examples/sign_file.rs

@@ -0,0 +1,34 @@
+use std::io::Read;
+use std::fs::File;
+use ring::digest;
+use virt_enclave::sig::*;
+
+fn main() {
+    let mut args = std::env::args();
+    args.next();
+    let signing_key_pair = match SigningKeyPair::read_from_file("platform_signing_key.json") {
+        Err(_) => { println!("Read file failed!"); return; },
+        Ok(k) => k,
+    };
+    let f = match args.next() {
+        None => { println!("File not assigned!"); return; },
+        Some(f) => f,
+    };
+    let mut file = match File::open(&f) {
+        Err(_) => { println!("Open file failed: {}", f); return; }
+        Ok(f) => f,
+    };
+    let mut buf = vec![];
+    let _len = match file.read_to_end(&mut buf) {
+        Err(_) => { println!("Read file failed: {}", f); return; }
+        Ok(c) => c,
+    };
+    let d = digest::digest(&digest::SHA256, &buf);
+    let digest_hex = hex::encode(&d);
+    let mut signed_message = SignedMessage::new(d.as_ref().to_vec(), None);
+    signed_message.sign(&signing_key_pair);
+
+    println!("File  : {}", f);
+    println!("Hex   : {}", digest_hex);
+    println!("Signed: {}", serde_json::to_string(&signed_message).unwrap());
+}