Initial fuzzer setup for X25519 (#15)

* Initial fuzzer setup for X25519 (see orion-rs/orion#197)

* NIT

* Update Cargo.toml

Cargo.toml

@@ -14,6 +14,7 @@ blake2-rfc = "0.2.18"
 chacha = "0.3.0"
 orion = { git = "https://github.com/orion-rs/orion", branch = "master" }
 rust-argon2 = "0.8.3"
+x25519-dalek = "1.2.0"
 
 [[bin]]
 name = "high_level_api"
@@ -47,5 +48,9 @@ path = "src/kdf.rs"
 name = "aead_stream"
 path = "src/aead_stream.rs"
 
+[[bin]]
+name = "ecc"
+path = "src/ecc.rs"
+
 [profile.release]
-opt-level = 3
+opt-level = 3

src/ecc.rs

@@ -0,0 +1,50 @@
+#[macro_use]
+extern crate honggfuzz;
+extern crate orion;
+extern crate x25519_dalek;
+
+use orion::hazardous::ecc::x25519;
+use std::convert::{TryFrom, TryInto};
+use utils::{make_seeded_rng, ChaChaRng, RngCore};
+
+pub mod utils;
+
+/// `orion::hazardous::ecc::x25519`
+fn fuzz_x25519(seeded_rng: &mut ChaChaRng) {
+    // Key-agreement
+    let mut alice_k = [0u8; x25519::SECRET_KEY_SIZE];
+    let mut bob_k = [0u8; x25519::SECRET_KEY_SIZE];
+    seeded_rng.fill_bytes(&mut alice_k);
+    seeded_rng.fill_bytes(&mut bob_k);
+
+    let alice_secret = x25519::SecretKey::from_slice(&alice_k).unwrap();
+    let alice_public = x25519::PublicKey::try_from(&alice_secret).unwrap();
+    let bob_secret = x25519::SecretKey::from_slice(&bob_k).unwrap();
+    let bob_public = x25519::PublicKey::try_from(&bob_secret).unwrap();
+
+    let alice_shared = x25519::key_agreement(&alice_secret, &bob_public).unwrap();
+    let bob_shared = x25519::key_agreement(&bob_secret, &alice_public).unwrap();
+
+    assert_eq!(alice_shared, bob_shared);
+
+    // x25519_dalek (we use the bare-byte function since this is the one documented as adherent to RFC)
+    let dalek_alice_public: [u8; 32] = alice_public.as_ref().try_into().unwrap();
+    let dalek_bob_public: [u8; 32] = bob_public.as_ref().try_into().unwrap();
+    let dalek_alice_shared = x25519_dalek::x25519(alice_k, dalek_bob_public);
+    let dalek_bob_shared = x25519_dalek::x25519(bob_k, dalek_alice_public);
+
+    assert_eq!(alice_shared, dalek_alice_shared.as_ref());
+    assert_eq!(bob_shared, dalek_bob_shared.as_ref());
+}
+
+fn main() {
+    loop {
+        fuzz!(|data: &[u8]| {
+            // Seed the RNG
+            let mut seeded_rng = make_seeded_rng(data);
+
+            // Test `orion::hazardous::ecc::x25519`
+            fuzz_x25519(&mut seeded_rng);
+        });
+    }
+}