Refactoring ecdh to work properly as a lib, extending it to use with …

…other curves (#29)

.github/workflows/main.yml

@@ -32,7 +32,7 @@ jobs:
                   bun-version: latest
             - uses: noir-lang/noirup@v0.1.3
               with:
-                  toolchain: 0.39.0
+                  toolchain: 1.0.0-beta.1
             - run: bun i
             - run: bun fmt
 
@@ -44,5 +44,5 @@ jobs:
             - uses: actions/checkout@v4
             - uses: noir-lang/noirup@v0.1.3
               with:
-                  toolchain: 0.39.0
+                  toolchain: 1.0.0-beta.1
             - run: nargo test

packages/ecdh/Nargo.toml

@@ -1,8 +1,7 @@
 [package]
 name = "ecdh"
-type = "bin"
-authors = ["YashBit"]
-compiler_version = ">=0.39.0"
+type = "lib"
+authors = ["YashBit", "signorecello"]
 
 [dependencies]
-ec = { tag = "v0.1.2", git = "https://github.com/noir-lang/ec" }
+ec = { tag = "master", git = "https://github.com/noir-lang/ec" }

packages/ecdh/README.md

@@ -1,35 +1,28 @@
-# ECDH Library using Baby JubJub Curve
+# ECDH Library
 
-This repository introduces a set of functions and utilities for elliptic curve cryptography using the Baby JubJub curve. The library provides essential operations for the Elliptic Curve Diffie-Hellman (ECDH) protocol, along with utility functions for key generation, field element conversion, and shared key computation.
+This repository introduces a set of functions and utilities for elliptic curve cryptography using. The library provides essential operations for the Elliptic Curve Diffie-Hellman (ECDH) protocol, along with utility functions for key generation, field element conversion, and shared key computation.
 
-## Features
-
-- **Byte Array to Field Element Conversion:** Utility functions to convert byte arrays into field elements for use in elliptic curve operations.
-- **Public Key Generation:** Generate public keys from private keys using the Baby JubJub curve, with both standard and optimized methods.
-- **Shared Key Computation:** Compute shared keys for secure communication using the ECDH protocol.
-- **Main Function:** A main function to generate ECDH shared keys, demonstrating the usage of the library.
-- **Testing:** Comprehensive tests to verify the correctness of key derivation and field conversion functions.
-
-## Compiling the Circuit
+At the moment only Baby JubJub is supported, feel free to contribute with more curves.
 
-To compile the circuit, navigate one directory above the source code and run the following command:
+## Features
 
-```bash
-nargo compile
-```
+- **Public Key Generation:** Generate public keys from private keys.
+- **Shared Key Computation:** Compute shared keys for secure communication.
 
-## Running Tests
+## Usage
 
-To run the tests for this library, use the following command:
+To use this library, add the dependency to your `Nargo.toml`:
 
-```bash
-bun run test
+```toml
+ecdh = { git = "https://github.com/privacy-scaling-explorations/zk-kit.noir", tag = "main", directory = "packages/ecdh" }
 ```
 
-## Running Tests with Mocha
+You can then import the ECDH implementation for the curve you're working with, like so:
 
-To run the tests using Mocha with TypeScript, use the following command:
+```rust
+use ecdh::bjj::BJJ; // only Baby JubJub is supported at the moment
+let ecdh = BJJ::new(your_private_key);
+let public_key = ecdh.derive_public_key();
 
-```bash
-npx mocha -r ts-node/register tests/ecdh.tests.ts
+let shared_key = ecdh.derive_shared_key(someone_elses_public_key);
 ```

packages/ecdh/src/bjj.nr

@@ -0,0 +1,24 @@
+use crate::ECDHTrait;
+use ec::consts::te::{baby_jubjub, BabyJubjub};
+use ec::tecurve::affine::Point;
+
+pub struct BJJ {
+    pub private_key: Field,
+    pub bjj: BabyJubjub,
+}
+
+impl ECDHTrait for BJJ {
+    fn new(private_key: Field) -> Self {
+        let bjj = baby_jubjub();
+        Self { bjj, private_key }
+    }
+
+    fn derive_public_key(self) -> Point {
+        self.bjj.curve.mul(self.private_key, self.bjj.base8)
+    }
+
+    fn derive_shared_key(self, public_key: Point) -> Field {
+        let shared_key = self.bjj.curve.mul(self.private_key, public_key);
+        shared_key.x
+    }
+}

packages/ecdh/src/lib.nr

@@ -1,58 +1,8 @@
-mod globals;
-use ec::tecurve::affine::{Curve, Point};
+mod bjj;
+use ec::tecurve::affine::Point;
 
-// @@@@@@ Core ECDH Implementation
-
-/// Converts a byte array to a field element.
-/// # Arguments
-/// * `bytes` - A fixed-size array of 32 bytes.
-/// * `big_endian` - A boolean indicating if the byte array is in big-endian format.
-/// # Returns
-/// A `Field` element representing the converted byte array.
-pub fn field_from_bytes(bytes: [u8; 32], big_endian: bool) -> Field {
-    let mut as_field: Field = 0;
-    let mut offset: Field = 1;
-
-    for i in 0..32 {
-        let index = if big_endian { 31 - i } else { i };
-        as_field += (bytes[index] as Field) * offset;
-        offset *= 256;
-    }
-
-    as_field
-}
-
-/// Computes a public key from a private key using the Baby JubJub curve.
-/// # Arguments
-/// * `private_key` - The private key as a `Field` element.
-/// # Returns
-/// The corresponding `Point` on the Baby JubJub curve.
-pub fn derive_public_key(private_key: Field) -> Point {
-    let base_point = Point::new(
-        5299619240641551281634865583518297030282874472190772894086521144482721001553,
-        16950150798460657717958625567821834550301663161624707787222815936182638968203,
-    );
-    let baby_jubjub_curve = Curve::new(168700, 168696, base_point);
-    baby_jubjub_curve.mul(private_key, base_point)
-}
-
-/// Optimized public key derivation using Baby JubJub curve.
-/// # Arguments
-/// * `private_key` - The private key as a `Field` element.
-/// # Returns
-/// The public key as a `Point` on the Baby JubJub curve.
-pub fn derive_public_key_optimized(private_key: Field) -> Point {
-    let X = globals::BJJ.curve.mul(private_key, globals::G);
-    X
-}
-
-/// Computes a shared secret key using ECDH with the Baby JubJub curve.
-/// # Arguments
-/// * `private_key` - The private key as a `Field` element.
-/// * `public_key` - The public key as a `Point` on the Baby JubJub curve.
-/// # Returns
-/// The shared secret key as a `Field` element.
-pub fn derive_shared_key(private_key: Field, public_key: Point) -> Field {
-    let shared_key = globals::BJJ.curve.mul(private_key, public_key);
-    shared_key.x
+pub trait ECDHTrait {
+    fn new(private_key: Field) -> Self;
+    fn derive_public_key(self) -> Point;
+    fn derive_shared_key(self, public_key: Point) -> Field;
 }

packages/merkle-trees/Nargo.toml

@@ -2,4 +2,3 @@
 name = "merkle_trees"
 type = "lib"
 authors = ["fabianschu", "signorecello"]
-compiler_version = ">=0.39.0"

tests/Nargo.toml

@@ -1,9 +1,10 @@
 [package]
-name = "merkle_trees"
+name = "zk_kit_tests"
 type = "lib"
-authors = ["fabianschu", "signorecello"]
-compiler_version = ">=0.39.0"
+authors = ["signorecello"]
 
 [dependencies]
-bignum = { git = "https://github.com/noir-lang/noir-bignum", tag = "zpedro/default_trait" }
+bignum = { git = "https://github.com/noir-lang/noir-bignum", tag = "main" }
 trees = { path = "../packages/merkle-trees" }
+ecdh = { path = "../packages/ecdh" }
+ec = { tag = "master", git = "https://github.com/noir-lang/ec" }

tests/src/ecdh/mod.nr

@@ -0,0 +1,30 @@
+use ec::tecurve::affine::Point;
+use ecdh::bjj::BJJ;
+
+global alice_sk: Field = 0x60c0102756aac2cf5d7277792a469bff83dfe3d3e7e50ad5a55383f3a89283e;
+global bob_sk: Field = 0x86cdaad8886954a2eb20142fb98468d476a2d6c7b2c571af42cdc041b1a923c;
+
+#[test]
+fn test_pk() {
+    let ecdh = BJJ::new(alice_sk);
+    let expected_pk = Point::new(
+        0x17d6ff45a37eee4ca071bb451c09b47184ed67492c6bac9279fb0a7d2d4ad1dc,
+        0x02d3a6338eee1ae8a38b278ce6c13179889c780f5e0d7294b904b0fa52c7dc3e,
+    );
+    let pk = ecdh.derive_public_key();
+    assert(pk == expected_pk);
+}
+
+#[test]
+fn test_shared_k() {
+    let alice_ecdh = BJJ::new(alice_sk);
+    let bob_ecdh = BJJ::new(bob_sk);
+
+    let alice_pk: Point = alice_ecdh.derive_public_key();
+    let bob_pk: Point = bob_ecdh.derive_public_key();
+
+    let shared_key_with_bob = alice_ecdh.derive_shared_key(bob_pk);
+    let shared_key_with_alice = bob_ecdh.derive_shared_key(alice_pk);
+
+    assert(shared_key_with_bob == shared_key_with_alice);
+}

tests/src/lib.nr

@@ -1,2 +1,3 @@
 mod mt;
 mod smt;
+mod ecdh;