feat: implement ECDH

.dprint.jsonc

@@ -19,6 +19,8 @@
     "yarn.lock",
     ".yarn",
     "packages/merkle-trees/src/globals.nr",
+    "packages/ecdh/src/globals.nr",
+    "target/",
   ],
   "plugins": [
     "https://plugins.dprint.dev/json-0.19.3.wasm",

.husky/commit-msg

@@ -2,3 +2,4 @@
 . "$(dirname -- "$0")/_/husky.sh"
 
 npx --no-install commitlint --edit $1
+

.mocharc.json

@@ -0,0 +1,8 @@
+{
+  "require": "ts-node/register",
+  "spec": "packages/ecdh/tests/**/*.test.ts",
+  "timeout": 20000,
+  "recursive": true,
+  "parallel": false,
+  "exit": true
+}

Nargo.toml

@@ -1,2 +1,2 @@
 [workspace]
-members = ["packages/merkle-trees"]
+members = ["packages/ecdh", "packages/merkle-trees"]

README.md

@@ -63,6 +63,7 @@
 ## 📦 Packages
 
 - [merkle-trees](https://github.com/privacy-scaling-explorations/zk-kit.noir/tree/main/packages/merkle-trees)
+- [ecdh](https://github.com/privacy-scaling-explorations/zk-kit.noir/tree/main/packages/ecdh)
 
 ## 👥 Ways to contribute
 

package.json

@@ -10,7 +10,8 @@
     "check": "dprint check",
     "fmt": "dprint fmt",
     "postinstall": "husky && git config --local core.editor cat",
-    "test": "nargo test",
+    "build": "nargo compile",
+    "test": "npm run build && mocha && nargo test --workspace",
     "version:release": "changelogithub"
   },
   "keywords": [
@@ -25,12 +26,22 @@
   ],
   "packageManager": "[email protected]",
   "devDependencies": {
-    "@commitlint/cli": "^18.6.1",
-    "@commitlint/config-conventional": "^18.6.2",
+    "@commitlint/cli": "^19.3.0",
+    "@commitlint/config-conventional": "^19.2.2",
+    "@types/chai": "^4",
+    "@types/mocha": "^10",
     "changelogithub": "patch:changelogithub@npm%3A0.13.3#~/.yarn/patches/changelogithub-npm-0.13.3-1783949906.patch",
     "czg": "^1.9.1",
     "dprint": "^0.46.3",
-    "husky": "^9.0.11",
-    "lint-staged": "^15.2.2"
-  }
+    "husky": "4",
+    "lint-staged": "^15.2.2",
+    "ts-node": "^10.9.2",
+    "typescript": "^5.5.4",
+    "@noir-lang/backend_barretenberg": "^0.30.0",
+    "@noir-lang/noir_js": "^0.30.0",
+    "@noir-lang/noir_wasm": "^0.32.0",
+    "chai": "^4.5.0",
+    "mocha": "^10.7.0"
+  },
+  "dependencies": {}
 }

packages/ecdh/Nargo.toml

@@ -0,0 +1,5 @@
+[package]
+name = "ecdh"
+type = "bin"
+authors = ["YashBit"]
+compiler_version = ">=0.30.0"

packages/ecdh/README.md

@@ -0,0 +1,35 @@
+# ECDH Library using Baby JubJub Curve
+
+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.
+
+## 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
+
+To compile the circuit, navigate one directory above the source code and run the following command:
+
+```bash
+nargo compile
+```
+
+## Running Tests
+
+To run the tests for this library, use the following command:
+
+```bash
+yarn test
+```
+
+## Running Tests with Mocha
+
+To run the tests using Mocha with TypeScript, use the following command:
+
+```bash
+npx mocha -r ts-node/register tests/ecdh.tests.ts
+```

packages/ecdh/src/globals.nr

@@ -0,0 +1,5 @@
+// Globals Edward Curves supported Baby JubJub
+use dep::std::ec::consts::te::{baby_jubjub};
+
+global BJJ = baby_jubjub();
+global G = BJJ.base8;

packages/ecdh/src/lib.nr

@@ -0,0 +1,58 @@
+mod globals;
+use dep::std::ec::tecurve::affine::{Curve, 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
+}

packages/ecdh/src/main.nr

@@ -0,0 +1,45 @@
+mod lib;
+// ECDH Circuit
+fn main(private_key1: [u8; 32], private_key2: [u8; 32]) {
+    // Convert private keys to fields
+    let private_key1_as_field = lib::field_from_bytes(private_key1, true);
+    let private_key2_as_field = lib::field_from_bytes(private_key2, true);
+
+    // Generate public keys from private keys
+    let public_key1 = lib::derive_public_key_optimized(private_key1_as_field);
+    let public_key2 = lib::derive_public_key_optimized(private_key2_as_field);
+
+    // Generate Both ECDH Shared Keys - Scalar Multiply
+    let shared_key1 = lib::derive_shared_key(private_key2_as_field, public_key1);
+    let shared_key2 = lib::derive_shared_key(private_key1_as_field, public_key2);
+    assert(shared_key1 == shared_key2);
+}
+
+// ########## Tests ##########
+
+// Description: This test verifies the correctness of the optimized public key derivation function.
+// It ensures that the `derive_public_key_optimized` function produces the same result as the
+// standard `derive_public_key` function for a given test input.
+
+#[test]
+fn test_derive_public_key() {
+    let test_field_value = 0x3fbbccb240537392421955b07a0d65eded9e7637995bf2f9cfe29e19b580e4;
+    let derived_public_key = lib::derive_public_key_optimized(test_field_value);
+    let test_derived_public_key = lib::derive_public_key(test_field_value);
+    assert(derived_public_key.x == test_derived_public_key.x);
+    assert(derived_public_key.y == test_derived_public_key.y);
+}
+
+/// Test that the `field_from_bytes` function correctly converts a 32-byte array of zeroes to a field element with a value of `0`.
+///
+/// This test ensures that:
+/// - The input is a 32-byte array initialized with zeroes.
+/// - The `field_from_bytes` function is called with the input and a boolean flag set to `true`.
+/// - The output is asserted to be `0`, verifying that the conversion is correct.
+#[test]
+// Define the test function for `field_from_bytes`
+fn field_from_bytes_correct() {
+    let bytes: [u8; 32] = [0; 32];
+    let field_result = lib::field_from_bytes(bytes, true);
+    assert_eq(field_result, 0);
+}

packages/ecdh/tests/ecdh.test.ts

@@ -0,0 +1,47 @@
+import { BarretenbergBackend } from '@noir-lang/backend_barretenberg'
+import { Noir } from '@noir-lang/noir_js'
+import { ProofData } from '@noir-lang/types'
+import { expect } from 'chai'
+import { randomBytes } from 'crypto'
+import { readFileSync } from 'fs'
+import { resolve } from 'path'
+import 'mocha'
+
+function generatePrivateKey(): Uint8Array {
+  return randomBytes(32)
+}
+
+describe('ECDH Circuit Tests', function() {
+  let noir: Noir
+  let backend: BarretenbergBackend
+  let correctProof: ProofData
+
+  beforeEach(async () => {
+    const circuitFile = readFileSync(resolve(__dirname, '../../../target/ecdh.json'), 'utf-8')
+    const circuit = JSON.parse(circuitFile)
+    backend = new BarretenbergBackend(circuit)
+    noir = new Noir(circuit, backend)
+    const pk1 = generatePrivateKey()
+    const pk2 = generatePrivateKey()
+
+    // Convert Uint8Array to regular arrays
+    const input = {
+      private_key1: Array.from(pk1),
+      private_key2: Array.from(pk2),
+    }
+
+    correctProof = await noir.generateProof(input)
+  })
+
+  it('Should generate valid proof for correct input', async function() {
+    this.timeout(25000) // Optional: Increase timeout if needed
+    expect(correctProof.proof).to.be.instanceOf(Uint8Array)
+  })
+
+  it('Should verify valid proof for correct input', async function() {
+    this.timeout(25000) // Increase timeout if needed
+    expect(correctProof).to.not.be.undefined // Ensure proof is generated
+    const verification = await noir.verifyProof(correctProof)
+    expect(verification).to.be.true
+  })
+})

tsconfig.json

@@ -0,0 +1,20 @@
+{
+  "compilerOptions": {
+    "outDir": "./dist",
+    "rootDir": ".",
+    "module": "commonjs",
+    "target": "es6",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "resolveJsonModule": true, // Add this line
+    "types": ["mocha", "node"]
+  },
+  "include": [
+    "./src/**/*.ts",
+    "./tests/**/*.ts"
+  ],
+  "exclude": [
+    "./dist"
+  ]
+}