NeoX TPKE

A TypeScript library for Threshold Public Key Encryption (TPKE) utilities in the NeoX ecosystem.

Overview

NeoX TPKE provides cryptographic utilities for threshold encryption, allowing messages to be encrypted with a public key that can only be decrypted when a threshold number of private key holders collaborate. This is particularly useful for secure consensus mechanisms and distributed systems.

Installation

npm:

npm install neox-tpke

yarn:

yarn add neox-tpke

pnpm:

pnpm add neox-tpke

Features

• BLS-based threshold encryption
• Public key generation from aggregated commitments
• AES encryption for message content
• Utilities for consensus threshold calculation
• Serialization and deserialization of cryptographic objects

Usage

Creating a Public Key

import { PublicKey } from 'neox-tpke';
import { toBytes } from 'viem';

// From raw bytes
const publicKey = PublicKey.fromBytes(
  toBytes(
    '0xa5aa188d1c60a7173e59fe49b68b969999e70aa4c1acb76c5a3dd2ad0d19a859b1a2759e3995ce1ceccdea5a57fbf637',
  ),
);

// From aggregated commitment
import { getConsensusThreshold, getScaler } from 'neox-tpke';

const consensusSize = 7n;
const threshold = getConsensusThreshold(consensusSize);
const scaler = getScaler(consensusSize, threshold);

const publicKey = PublicKey.fromAggregatedCommitment(aggregatedCommitmentBytes, scaler);

Encrypting Messages

import { PublicKey } from 'neox-tpke';
import { toBytes, concat, pad } from 'viem';

// Create a public key
const publicKey = PublicKey.fromBytes(publicKeyBytes);

// Encrypt a message (e.g., a transaction)
const { encryptedKey, encryptedMsg } = publicKey.encrypt(messageBytes);

// Format as envelope data (example)
const roundNumber = 1;
const envelopeData = concat([
  new Uint8Array([0xff, 0xff, 0xff, 0xff]),
  pad(toBytes(roundNumber), { size: 4 }).reverse(),
  encryptedKey,
  encryptedMsg,
]);

Consensus Utilities

import { getConsensusThreshold, getScaler } from 'neox-tpke';

// Calculate consensus threshold for a given size
const consensusSize = 7n;
const threshold = getConsensusThreshold(consensusSize);

// Calculate scaler for a given size and threshold
const scaler = getScaler(consensusSize, threshold);

API Reference

PublicKey

• PublicKey.fromBytes(bytes: ByteArray): PublicKey - Create a public key from raw bytes
• PublicKey.fromAggregatedCommitment(aggregatedCommitment: ByteArray, scaler: bigint): PublicKey - Create a public key from an aggregated commitment
• publicKey.toBytes(): ByteArray - Convert public key to raw bytes
• publicKey.encrypt(msg: ByteArray): { encryptedKey: ByteArray; encryptedMsg: ByteArray } - Encrypt a message using the public key

Utilities

• getConsensusThreshold(consensusSize: bigint): bigint - Calculate the consensus threshold for a given size
• getScaler(size: bigint, threshold: bigint): bigint - Calculate the scaler for a given size and threshold

Dependencies

• @noble/curves - For elliptic curve operations
• aes-js - Advanced Encryption Standard (AES) implementation
• bigint-crypto-utils - For bigint cryptographic utilities
• hash.js - Hash functions implemented in JavaScript
• viem - For Ethereum-related utilities

License

Licensed under the Apache License, Version 2.0. See the LICENSE file for details.

Copyright (c) 2025 Bane Labs