Refactor elliptic

.cspell.jsonc

@@ -8,8 +8,11 @@
     "bindgen",
     "chacha",
     "Codacy",
+    "Codecov",
     "consts",
     "Ctarget",
+    "dalek",
+    "diffie",
     "docsrs",
     "ecies",
     "eciespy",
@@ -32,7 +35,9 @@
   // flagWords - list of words to be always considered incorrect
   // This is useful for offensive words and common spelling errors.
   // For example "hte" should be "the"
-  "flagWords": ["hte"],
+  "flagWords": [
+    "hte"
+  ],
   "ignorePaths": [
     ".git",
     ".github",

.github/workflows/cd.yml

@@ -19,7 +19,7 @@ jobs:
 
       - uses: dtolnay/rust-toolchain@master
         with:
-          toolchain: ${{ matrix.toolchain }}
+          toolchain: stable
           target: wasm32-unknown-unknown
 
       - run: cargo generate-lockfile

Cargo.toml

@@ -1,12 +1,13 @@
 [package]
 name = "ecies"
-version = "0.2.6"
+version = "0.2.7"
 # docs
 authors = ["Weiliang Li <[email protected]>"]
-description = "Elliptic Curve Integrated Encryption Scheme for secp256k1 in Rust"
+description = "Elliptic Curve Integrated Encryption Scheme for secp256k1/curve25519"
 edition = "2021"
 keywords = [
   "secp256k1",
+  "curve25519",
   "crypto",
   "ecc",
   "ecies",
@@ -21,11 +22,14 @@ repository = "https://github.com/ecies/rs"
 
 [dependencies]
 hkdf = {version = "0.12.3", default-features = false}
-libsecp256k1 = {version = "0.7.1", default-features = false, features = ["static-context"]}
 sha2 = {version = "0.10.7", default-features = false}
 
+# elliptic curves
+libsecp256k1 = {version = "0.7.1", default-features = false, features = ["static-context"], optional = true}
+x25519-dalek = {version = "2.0.0", default-features = false, features = ["static_secrets"], optional = true}
+
 # openssl aes
-openssl = {version = "0.10.56", default-features = false, optional = true}
+openssl = {version = "0.10.57", default-features = false, optional = true}
 
 # pure rust aes
 aes-gcm = {version = "0.10.2", default-features = false, optional = true}
@@ -52,16 +56,21 @@ wasm-bindgen = {version = "0.2.87", default-features = false}
 once_cell = {version = "1.18.0", default-features = false, features = ["std"]}
 
 [features]
+default = ["openssl"]
 std = ["hkdf/std", "sha2/std", "once_cell/std"]
 
-default = ["openssl"]
+# curve
+secp256k1 = ["libsecp256k1"]
+x25519 = ["x25519-dalek"]
 
-aes-12bytes-nonce = [] # with feature "openssl" or "pure". default: 16 bytes
-pure = ["aes-gcm/aes", "typenum"]
-xchacha20 = ["chacha20poly1305"]
+# cipher
+aes-12bytes-nonce = ["secp256k1"] # with feature "openssl" or "pure". default: 16 bytes
+openssl = ["dep:openssl", "secp256k1"]
+pure = ["aes-gcm/aes", "typenum", "secp256k1"]
+xchacha20 = ["chacha20poly1305", "secp256k1"]
 
 [dev-dependencies]
-criterion = {version = "0.5.1", default-features = false}
+criterion = {version = "0.4.0", default-features = false}
 hex = {version = "0.4.3", default-features = false, features = ["alloc"]}
 
 [target.'cfg(target_arch = "wasm32")'.dev-dependencies]

README.md

@@ -28,7 +28,10 @@ use ecies::{decrypt, encrypt, utils::generate_keypair};
 
 const MSG: &str = "helloworld🌍";
 let (sk, pk) = generate_keypair();
+#[cfg(not(feature = "x25519"))]
 let (sk, pk) = (&sk.serialize(), &pk.serialize());
+#[cfg(feature = "x25519")]
+let (sk, pk) = (sk.as_bytes(), pk.as_bytes());
 
 let msg = MSG.as_bytes();
 assert_eq!(

src/config.rs

@@ -1,8 +1,6 @@
 use once_cell::sync::Lazy;
 use parking_lot::RwLock;
 
-use crate::consts::{COMPRESSED_PUBLIC_KEY_SIZE, UNCOMPRESSED_PUBLIC_KEY_SIZE};
-
 /// ECIES config. Make sure all parties use the same config
 #[derive(Default)]
 pub struct Config {
@@ -32,81 +30,23 @@ pub fn is_ephemeral_key_compressed() -> bool {
 }
 
 /// Get ephemeral key size: compressed(33) or uncompressed(65)
+#[cfg(not(feature = "x25519"))]
 pub fn get_ephemeral_key_size() -> usize {
+    use crate::consts::{COMPRESSED_PUBLIC_KEY_SIZE, UNCOMPRESSED_PUBLIC_KEY_SIZE};
+
     if is_ephemeral_key_compressed() {
         COMPRESSED_PUBLIC_KEY_SIZE
     } else {
         UNCOMPRESSED_PUBLIC_KEY_SIZE
     }
 }
 
+#[cfg(feature = "x25519")]
+pub fn get_ephemeral_key_size() -> usize {
+    32
+}
+
 /// Get hkdf key derived from compressed shared point or not
 pub fn is_hkdf_key_compressed() -> bool {
     ECIES_CONFIG.read().is_hkdf_key_compressed
 }
-
-#[cfg(test)]
-mod tests {
-    use super::{reset_config, update_config, Config};
-    use libsecp256k1::PublicKey;
-
-    use crate::{
-        decrypt, encrypt,
-        utils::{
-            encapsulate, generate_keypair,
-            tests::{decode_hex, get_sk2_sk3},
-        },
-    };
-
-    const MSG: &str = "helloworld🌍";
-
-    #[test]
-    pub(super) fn test_known_hkdf_config() {
-        let (sk2, sk3) = get_sk2_sk3();
-        let pk3 = PublicKey::from_secret_key(&sk3);
-
-        update_config(Config {
-            is_hkdf_key_compressed: true,
-            ..Config::default()
-        });
-
-        let encapsulated = encapsulate(&sk2, &pk3).unwrap();
-
-        assert_eq!(
-            encapsulated.to_vec(),
-            decode_hex("b192b226edb3f02da11ef9c6ce4afe1c7e40be304e05ae3b988f4834b1cb6c69")
-        );
-
-        reset_config();
-    }
-
-    #[test]
-    pub(super) fn test_ephemeral_key_config() {
-        let (sk, pk) = generate_keypair();
-        let (sk, pk) = (&sk.serialize(), &pk.serialize_compressed());
-        let encrypted_1 = encrypt(pk, MSG.as_bytes()).unwrap();
-        assert_eq!(MSG.as_bytes(), &decrypt(sk, &encrypted_1).unwrap());
-
-        update_config(Config {
-            is_ephemeral_key_compressed: true,
-            ..Config::default()
-        });
-
-        let encrypted_2 = encrypt(pk, MSG.as_bytes()).unwrap();
-        assert_eq!(encrypted_1.len() - encrypted_2.len(), 32);
-        assert_eq!(MSG.as_bytes(), &decrypt(sk, &encrypted_2).unwrap());
-
-        reset_config();
-    }
-}
-
-#[cfg(all(test, target_arch = "wasm32"))]
-mod wasm_tests {
-    use wasm_bindgen_test::*;
-
-    #[wasm_bindgen_test]
-    fn test_wasm() {
-        super::tests::test_ephemeral_key_config();
-        super::tests::test_known_hkdf_config();
-    }
-}

src/consts.rs

@@ -19,3 +19,6 @@ pub const NONCE_TAG_LENGTH: usize = NONCE_LENGTH + AEAD_TAG_LENGTH;
 
 /// Empty bytes array
 pub const EMPTY_BYTES: [u8; 0] = [];
+
+/// Shared secret derived from key exchange by hkdf
+pub type SharedSecret = [u8; 32];

src/elliptic/mod.rs

@@ -0,0 +1,50 @@
+use hkdf::Hkdf;
+use sha2::Sha256;
+
+use crate::compat::Vec;
+use crate::consts::{SharedSecret, EMPTY_BYTES};
+
+#[cfg(not(feature = "x25519"))]
+mod secp256k1;
+#[cfg(not(feature = "x25519"))]
+pub use secp256k1::{decapsulate, encapsulate, generate_keypair};
+#[cfg(not(feature = "x25519"))]
+pub(crate) use secp256k1::{parse_pk, parse_sk, pk_to_vec, Error};
+
+#[cfg(feature = "x25519")]
+mod x25519;
+#[cfg(feature = "x25519")]
+pub use x25519::{decapsulate, encapsulate, generate_keypair};
+#[cfg(feature = "x25519")]
+pub(crate) use x25519::{parse_pk, parse_sk, pk_to_vec, Error};
+
+fn hkdf_derive(sender_point: &[u8], shared_point: &[u8]) -> SharedSecret {
+    let size = sender_point.len() + shared_point.len();
+    let mut master = Vec::with_capacity(size);
+    master.extend(sender_point);
+    master.extend(shared_point);
+    hkdf_sha256(&master)
+}
+
+fn hkdf_sha256(master: &[u8]) -> SharedSecret {
+    let h = Hkdf::<Sha256>::new(None, master);
+    let mut out = [0u8; 32];
+    // never fails because 32 < 255 * chunk_len, which is 32 on SHA256
+    h.expand(&EMPTY_BYTES, &mut out).unwrap();
+    out
+}
+
+#[cfg(test)]
+mod tests {
+    use super::hkdf_sha256;
+
+    use crate::utils::tests::decode_hex;
+
+    #[test]
+    fn test_known_hkdf_vector() {
+        assert_eq!(
+            hkdf_sha256(b"secret").to_vec(),
+            decode_hex("2f34e5ff91ec85d53ca9b543683174d0cf550b60d5f52b24c97b386cfcf6cbbf")
+        );
+    }
+}