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new file mode 100644
index 0000000..f0b071f
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+++ b/__crypto/curve25519/Cargo.lock
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diff --git a/__crypto/curve25519/Cargo.toml b/__crypto/curve25519/Cargo.toml
new file mode 100644
index 0000000..8c2c5a5
--- /dev/null
+++ b/__crypto/curve25519/Cargo.toml
@@ -0,0 +1,14 @@
+[package]
+name = "curve25519"
+version = "0.1.0"
+authors = ["Hatter Jiang <jht5945@gmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+hex = "0.4.2"
+rand = "0.7.3"
+x25519-dalek = "1.1.0"
+ed25519-dalek = "1.0.1"
+curve25519-dalek = "3.0.0"
diff --git a/__crypto/curve25519/src/main.rs b/__crypto/curve25519/src/main.rs
new file mode 100644
index 0000000..2d087ef
--- /dev/null
+++ b/__crypto/curve25519/src/main.rs
@@ -0,0 +1,28 @@
+use rand::rngs::OsRng;
+use ed25519_dalek::{ Keypair, Signer, Verifier };
+use x25519_dalek::{EphemeralSecret, PublicKey};
+
+fn main() {
+    let mut csprng = OsRng{};
+    let keypair = Keypair::generate(&mut csprng);
+    println!("Key pair: {:#?}", keypair);
+
+    let message = b"This is sign test message.";
+    let signature = keypair.sign(message);
+    println!("Signature: {}", hex::encode(signature));
+
+    let public_key = keypair.public;
+    println!("Verify result: {:?}", public_key.verify(message, &signature));
+
+    // key exchange
+    let alice_secret = EphemeralSecret::new(OsRng);
+    let alice_public = PublicKey::from(&alice_secret);
+    let bob_secret = EphemeralSecret::new(OsRng);
+    let bob_public = PublicKey::from(&bob_secret);
+    
+    let alice_shared_secret = alice_secret.diffie_hellman(&bob_public);
+    let bob_shared_secret = bob_secret.diffie_hellman(&alice_public);
+
+    println!("Alice shared secret: {}", hex::encode(alice_shared_secret.as_bytes()));
+    println!("Bob   shared secret: {}", hex::encode(bob_shared_secret.as_bytes()));
+}