feat(rust/catalyst-voting): Jormungandr tx building (#60)

* move vote protocol under the vote_protocol mod

* add jormungandr tx struct

* add CipherText serde

* add EncryptedVote decoding functionality

* add new deserializers

* refactor

* wip

* wip

* replace thiserror with anyhow

* move decoding functionalities to separate module

* wip

* add test

* fix

* refactor

* fix tests

* wip

* wip

* fix spelling

* add v1::Tx generation functions

* add test

* refactor, add ElectionPublicKey, ElectionSecretKey

* fix

* fix with must_use

* fix docs

* refactor digest crate imports

* add ed25519 impl

* add ed25519 decoding functionality

* update v1::Tx

* add Tx signing

* wip

* fix

* wip

* add Blake2b-256 hash impl, update v1::Tx sign

* add txs::v1 doc test

* update rust docs

* make rng optional

* wip

* update v1::Tx decoding

* add signature and proof verification

* update verification

* update decoding test

* add decrypt_vote function

* add private_choice, public_choice methods

* fix spelling

.config/dictionaries/project.dic

@@ -29,6 +29,7 @@ CBOR
 cbork
 cdylib
 CEST
+chacha
 CHAINCODE
 chainsync
 childs

rust/catalyst-voting/Cargo.toml

@@ -13,7 +13,9 @@ workspace = true
 [dependencies]
 anyhow = "1.0.89"
 rand_core = "0.6.4"
-curve25519-dalek = { version = "4.1.3", features = ["digest"] }
+rand_chacha = "0.3.1"
+curve25519-dalek = { version = "4.1.3", features = ["digest", "rand_core"] }
+ed25519-dalek = { version = "2.1.1", features = ["rand_core"] }
 blake2b_simd = "1.0.2"
 
 [dev-dependencies]

rust/catalyst-voting/src/crypto/ed25519/decoding.rs

@@ -0,0 +1,42 @@
+//! `Ed25519` objects decoding implementation
+
+use ed25519_dalek::{
+    Signature as Ed25519Signature, VerifyingKey, PUBLIC_KEY_LENGTH, SIGNATURE_LENGTH,
+};
+
+use super::{PublicKey, Signature};
+
+impl PublicKey {
+    /// `PublicKey` bytes size
+    pub const BYTES_SIZE: usize = PUBLIC_KEY_LENGTH;
+
+    /// Convert this `PublicKey` to its underlying sequence of bytes.
+    #[must_use]
+    pub fn to_bytes(&self) -> [u8; Self::BYTES_SIZE] {
+        self.0.to_bytes()
+    }
+
+    /// Attempt to construct a `PublicKey` from a byte representation.
+    ///
+    /// # Errors
+    ///   - Cannot decode public key.
+    pub fn from_bytes(bytes: &[u8; Self::BYTES_SIZE]) -> anyhow::Result<Self> {
+        Ok(Self(VerifyingKey::from_bytes(bytes)?))
+    }
+}
+
+impl Signature {
+    /// `Signature` bytes size
+    pub const BYTES_SIZE: usize = SIGNATURE_LENGTH;
+
+    /// Convert this `Signature` to its underlying sequence of bytes.
+    #[must_use]
+    pub fn to_bytes(&self) -> [u8; Self::BYTES_SIZE] {
+        self.0.to_bytes()
+    }
+
+    /// Attempt to construct a `Signature` from a byte representation.
+    pub fn from_bytes(bytes: &[u8; Self::BYTES_SIZE]) -> Self {
+        Self(Ed25519Signature::from_bytes(bytes))
+    }
+}

rust/catalyst-voting/src/crypto/ed25519/mod.rs

@@ -0,0 +1,72 @@
+//! `EdDSA` digital signature scheme over Curve25519.
+
+mod decoding;
+
+use ed25519_dalek::{
+    ed25519::signature::Signer, Signature as Ed25519Signature, SigningKey, VerifyingKey,
+};
+use rand_core::CryptoRngCore;
+
+/// `Ed25519` private key struct.
+#[must_use]
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct PrivateKey(SigningKey);
+
+impl PrivateKey {
+    /// Randomly generate the `Ed25519` private key.
+    pub fn random<R: CryptoRngCore>(rng: &mut R) -> Self {
+        Self(SigningKey::generate(rng))
+    }
+
+    /// Get associated `Ed25519` public key.
+    pub fn public_key(&self) -> PublicKey {
+        PublicKey(self.0.verifying_key())
+    }
+}
+
+/// `Ed25519` public key struct.
+#[must_use]
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct PublicKey(VerifyingKey);
+
+/// `Ed25519` signature struct.
+#[must_use]
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Signature(Ed25519Signature);
+
+/// Sign a message using the `Ed25519` private key.
+pub fn sign(sk: &PrivateKey, msg: &[u8]) -> Signature {
+    Signature(sk.0.sign(msg))
+}
+
+/// Verify a `Ed25519` signature using the `Ed25519` public key.
+#[must_use]
+pub fn verify_signature(pk: &PublicKey, msg: &[u8], sig: &Signature) -> bool {
+    pk.0.verify_strict(msg, &sig.0).is_ok()
+}
+
+#[cfg(test)]
+mod tests {
+    use proptest::prelude::{any, Arbitrary, BoxedStrategy, Strategy};
+    use test_strategy::proptest;
+
+    use super::*;
+
+    impl Arbitrary for PrivateKey {
+        type Parameters = ();
+        type Strategy = BoxedStrategy<Self>;
+
+        fn arbitrary_with((): Self::Parameters) -> Self::Strategy {
+            any::<[u8; 32]>()
+                .prop_map(|b| PrivateKey(SigningKey::from_bytes(&b)))
+                .boxed()
+        }
+    }
+
+    #[proptest]
+    fn sign_test(private_key: PrivateKey, msg: Vec<u8>) {
+        let public_key = private_key.public_key();
+        let signature = sign(&private_key, &msg);
+        assert!(verify_signature(&public_key, &msg, &signature));
+    }
+}

rust/catalyst-voting/src/crypto/elgamal/decoding.rs

@@ -2,51 +2,14 @@
 
 use anyhow::anyhow;
 
-use super::{Ciphertext, GroupElement, PublicKey, Scalar, SecretKey};
-
-impl PublicKey {
-    /// `PublicKey` bytes size
-    pub const BYTES_SIZE: usize = GroupElement::BYTES_SIZE;
-
-    /// Convert this `PublicKey` to its underlying sequence of bytes.
-    #[must_use]
-    pub fn to_bytes(&self) -> [u8; Self::BYTES_SIZE] {
-        self.0.to_bytes()
-    }
-
-    /// Attempt to construct a `PublicKey` from a byte representation.
-    ///
-    /// # Errors
-    ///   - Cannot decode group element field.
-    pub fn from_bytes(bytes: &[u8; Self::BYTES_SIZE]) -> anyhow::Result<Self> {
-        GroupElement::from_bytes(bytes).map(Self)
-    }
-}
-
-impl SecretKey {
-    /// `SecretKey` bytes size
-    pub const BYTES_SIZE: usize = Scalar::BYTES_SIZE;
-
-    /// Convert this `SecretKey` to its underlying sequence of bytes.
-    #[must_use]
-    pub fn to_bytes(&self) -> [u8; Self::BYTES_SIZE] {
-        self.0.to_bytes()
-    }
-
-    /// Attempt to construct a `SecretKey` from a byte representation.
-    ///
-    /// # Errors
-    ///   - Cannot decode scalar field.
-    pub fn from_bytes(bytes: [u8; Self::BYTES_SIZE]) -> anyhow::Result<Self> {
-        Scalar::from_bytes(bytes).map(Self)
-    }
-}
+use super::{Ciphertext, GroupElement};
 
 impl Ciphertext {
     /// `Ciphertext` bytes size
     pub const BYTES_SIZE: usize = GroupElement::BYTES_SIZE * 2;
 
     /// Convert this `Ciphertext` to its underlying sequence of bytes.
+    #[must_use]
     pub fn to_bytes(&self) -> [u8; Self::BYTES_SIZE] {
         let mut res = [0; Self::BYTES_SIZE];
         res[0..32].copy_from_slice(&self.0.to_bytes());
@@ -58,6 +21,8 @@ impl Ciphertext {
     ///
     /// # Errors
     ///   - Cannot decode group element field.
+    ///
+    /// # Panics
     #[allow(clippy::unwrap_used)]
     pub fn from_bytes(bytes: &[u8; Self::BYTES_SIZE]) -> anyhow::Result<Self> {
         Ok(Self(
@@ -75,18 +40,6 @@ mod tests {
 
     use super::*;
 
-    #[proptest]
-    fn keys_to_bytes_from_bytes_test(s1: SecretKey) {
-        let bytes = s1.to_bytes();
-        let s2 = SecretKey::from_bytes(bytes).unwrap();
-        assert_eq!(s1, s2);
-
-        let p1 = s1.public_key();
-        let bytes = p1.to_bytes();
-        let p2 = PublicKey::from_bytes(&bytes).unwrap();
-        assert_eq!(p1, p2);
-    }
-
     #[proptest]
     fn ciphertext_to_bytes_from_bytes_test(c1: Ciphertext) {
         let bytes = c1.to_bytes();

rust/catalyst-voting/src/crypto/elgamal/mod.rs

@@ -1,55 +1,17 @@
-//! Implementation of the lifted ``ElGamal`` crypto system, and combine with `ChaCha`
+//! Implementation of the lifted `ElGamal` crypto system, and combine with `ChaCha`
 //! stream cipher to produce a hybrid encryption scheme.
 
 mod decoding;
 
-use std::ops::{Add, Deref, Mul};
-
-use rand_core::CryptoRngCore;
+use std::ops::{Add, Mul};
 
 use crate::crypto::group::{GroupElement, Scalar};
 
-/// ``ElGamal`` secret key.
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct SecretKey(Scalar);
-
-/// ``ElGamal`` public key.
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct PublicKey(GroupElement);
-
-/// ``ElGamal`` ciphertext, encrypted message with the public key.
+/// `ElGamal` ciphertext, encrypted message with the public key.
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[must_use]
 pub struct Ciphertext(GroupElement, GroupElement);
 
-impl Deref for SecretKey {
-    type Target = Scalar;
-
-    fn deref(&self) -> &Self::Target {
-        &self.0
-    }
-}
-
-impl Deref for PublicKey {
-    type Target = GroupElement;
-
-    fn deref(&self) -> &Self::Target {
-        &self.0
-    }
-}
-
-impl SecretKey {
-    /// Generate a random `SecretKey` value from the random number generator.
-    pub fn random<R: CryptoRngCore>(rng: &mut R) -> Self {
-        Self(Scalar::random(rng))
-    }
-
-    /// Generate a corresponding `PublicKey`.
-    #[must_use]
-    pub fn public_key(&self) -> PublicKey {
-        PublicKey(GroupElement::GENERATOR.mul(&self.0))
-    }
-}
-
 impl Ciphertext {
     /// Generate a zero `Ciphertext`.
     /// The same as encrypt a `Scalar::zero()` message and `Scalar::zero()` randomness.
@@ -68,19 +30,24 @@ impl Ciphertext {
     }
 }
 
+/// Generate `ElGamal` public key from the secret key value.
+pub fn generate_public_key(secret_key: &Scalar) -> GroupElement {
+    GroupElement::GENERATOR.mul(secret_key)
+}
+
 /// Given a `message` represented as a `Scalar`, return a ciphertext using the
-/// lifted ``ElGamal`` mechanism.
+/// lifted `ElGamal` mechanism.
 /// Returns a ciphertext of type `Ciphertext`.
-pub fn encrypt(message: &Scalar, public_key: &PublicKey, randomness: &Scalar) -> Ciphertext {
+pub fn encrypt(message: &Scalar, public_key: &GroupElement, randomness: &Scalar) -> Ciphertext {
     let e1 = GroupElement::GENERATOR.mul(randomness);
-    let e2 = &GroupElement::GENERATOR.mul(message) + &public_key.0.mul(randomness);
+    let e2 = &GroupElement::GENERATOR.mul(message) + &public_key.mul(randomness);
     Ciphertext(e1, e2)
 }
 
-/// Decrypt ``ElGamal`` `Ciphertext`, returns the original message represented as a
+/// Decrypt `ElGamal` `Ciphertext`, returns the original message represented as a
 /// `GroupElement`.
-pub fn decrypt(cipher: &Ciphertext, secret_key: &SecretKey) -> GroupElement {
-    &(&cipher.0 * &secret_key.0.negate()) + &cipher.1
+pub fn decrypt(cipher: &Ciphertext, secret_key: &Scalar) -> GroupElement {
+    &(&cipher.0 * &secret_key.negate()) + &cipher.1
 }
 
 impl Mul<&Scalar> for &Ciphertext {
@@ -109,15 +76,6 @@ mod tests {
 
     use super::*;
 
-    impl Arbitrary for SecretKey {
-        type Parameters = ();
-        type Strategy = BoxedStrategy<Self>;
-
-        fn arbitrary_with((): Self::Parameters) -> Self::Strategy {
-            any::<Scalar>().prop_map(SecretKey).boxed()
-        }
-    }
-
     impl Arbitrary for Ciphertext {
         type Parameters = ();
         type Strategy = BoxedStrategy<Self>;
@@ -152,10 +110,8 @@ mod tests {
     }
 
     #[proptest]
-    fn elgamal_encryption_decryption_test(
-        secret_key: SecretKey, message: Scalar, randomness: Scalar,
-    ) {
-        let public_key = secret_key.public_key();
+    fn elgamal_encryption_decryption_test(secret_key: Scalar, message: Scalar, randomness: Scalar) {
+        let public_key = generate_public_key(&secret_key);
 
         let cipher = encrypt(&message, &public_key, &randomness);
         let decrypted = decrypt(&cipher, &secret_key);

rust/catalyst-voting/src/crypto/group/ristretto255/mod.rs

@@ -11,20 +11,23 @@ use std::{
 
 use curve25519_dalek::{
     constants::{RISTRETTO_BASEPOINT_POINT, RISTRETTO_BASEPOINT_TABLE},
-    digest::{consts::U64, Digest},
-    ristretto::RistrettoPoint as Point,
     scalar::Scalar as IScalar,
     traits::Identity,
+    RistrettoPoint,
 };
 use rand_core::CryptoRngCore;
 
+use crate::crypto::hash::digest::{consts::U64, Digest};
+
 /// Ristretto group scalar.
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[must_use]
 pub struct Scalar(IScalar);
 
 /// Ristretto group element.
 #[derive(Debug, Clone, PartialEq, Eq)]
-pub struct GroupElement(Point);
+#[must_use]
+pub struct GroupElement(RistrettoPoint);
 
 impl From<u64> for Scalar {
     fn from(value: u64) -> Self {
@@ -41,9 +44,7 @@ impl Hash for GroupElement {
 impl Scalar {
     /// Generate a random scalar value from the random number generator.
     pub fn random<R: CryptoRngCore>(rng: &mut R) -> Self {
-        let mut scalar_bytes = [0u8; 64];
-        rng.fill_bytes(&mut scalar_bytes);
-        Scalar(IScalar::from_bytes_mod_order_wide(&scalar_bytes))
+        Scalar(IScalar::random(rng))
     }
 
     /// additive identity
@@ -84,7 +85,13 @@ impl GroupElement {
 
     /// Generate a zero group element.
     pub fn zero() -> Self {
-        GroupElement(Point::identity())
+        GroupElement(RistrettoPoint::identity())
+    }
+
+    /// Generate a `GroupElement` from a hash digest.
+    pub fn from_hash<D>(hash: D) -> GroupElement
+    where D: Digest<OutputSize = U64> + Default {
+        GroupElement(RistrettoPoint::from_hash(hash))
     }
 }