Merkle Tree Poseidon SDK

A TypeScript SDK for generating Merkle Tree proofs and selective disclosure inputs compatible with Poseidon-based Circom circuits.

This SDK is the companion to the official HARA-ORG/circom-zk repository, which contains the Circom circuit implementations and verification keys.

Features

• Poseidon Hashing: Uses circomlibjs for Snark-friendly hashing on the BN254 curve.
• Merkle Tree Proofs: Generates inclusion proofs for a fixed-depth (8) Merkle Tree.
• Selective Disclosure: Supports generating proof inputs for:
  • Numeric/Date Claims: Proves that a value is greater than or equal to a threshold (e.g., age verification).
  • String Claims: Proves equality to a known value without revealing the value itself (using Poseidon hashes).
• Identity Binding: Binds credentials to a public commitment (e.g., a wallet address).

Project Structure

src/
├── core/           # Low-level primitives (Poseidon, Merkle, Encoding)
├── sdk/            # Main SDK interface
└── index.ts        # Library entry point
tests/
└── sdk.test.ts     # Logic simulation (mirrors Circom constraints)

Installation

npm install

Scripts

Run Logic Simulation

Verifies the SDK's logic against a TypeScript implementation of the SelectiveDisclosure.circom constraints.

npm test

Build SDK

Compiles TypeScript into the dist/ directory.

npm run build

Usage Example

import { ZkIdentitySDK } from "merkle-tree-poseidon-sdk";

// 1. Define fields
const fields = [{ label: "credit_score", type: "number", value: 750 }];

// 2. Initialize SDK and build tree with a salt
const sdk = new ZkIdentitySDK(fields);
const salt = BigInt(123456);
await sdk.build(salt);

// 3. Generate input for SelectiveDisclosure circuit
const proofInput = await sdk.generateProofInput({
  label: "credit_score",
  identitySecret: BigInt("0x..."),
  publicCommitment: BigInt("0x..."),
  threshold: 700n,
});

// 4. Get the Merkle Root
const root = sdk.root;

// 5. Generate raw Merkle Proof
const { pathElements, pathIndices } =
  await sdk.generateMerkleProof("credit_score");

License

MIT