eciesjs

Elliptic Curve Integrated Encryption Scheme for secp256k1 in TypeScript.

This is the JavaScript/TypeScript version of eciespy with a built-in class-like secp256k1 API, you may go there for detailed documentation and learn the mechanism under the hood.

If you want a WASM version to run directly in modern browsers or on some blockchains, check ecies-wasm.

Install

npm install eciesjs

Quick Start

Run the code below with npx ts-node.

> import { encrypt, decrypt, PrivateKey } from 'eciesjs'
> const k1 = new PrivateKey()
> const data = Buffer.from('this is a test')
> decrypt(k1.toHex(), encrypt(k1.publicKey.toHex(), data)).toString()
'this is a test'

API

encrypt(receiverRawPK: string | Buffer, msg: Buffer): Buffer

Parameters:

• receiverRawPK - Receiver's secp256k1 public key, hex string or buffer
• msg - Data to encrypt

Returns: Buffer

decrypt(receiverRawSK: string | Buffer, msg: Buffer): Buffer

Parameters:

• receiverRawSK - Receiver's secp256k1 private key, hex string or buffer
• msg - Data to decrypt

Returns: Buffer

PrivateKey

• Methods

static fromHex(hex: string): PrivateKey;
constructor(secret?: Buffer);
toHex(): string;
encapsulate(pub: PublicKey): Buffer;
multiply(pub: PublicKey): Buffer;
equals(other: PrivateKey): boolean;

• Properties

readonly secret: Buffer;
readonly publicKey: PublicKey;

PublicKey

• Methods

static fromHex(hex: string): PublicKey;
constructor(buffer: Buffer);
toHex(compressed?: boolean): string;
decapsulate(priv: PrivateKey): Buffer;
equals(other: PublicKey): boolean;

• Properties

readonly uncompressed: Buffer;
readonly compressed: Buffer;

Configuration

Ephemeral key format in the payload and shared key in the key derivation can be configured as compressed or uncompressed format.

export type SymmetricAlgorithm = "aes-256-gcm" | "xchacha20";
export type NonceLength = 12 | 16; // bytes. Only for aes-256-gcm

class Config {
  isEphemeralKeyCompressed: boolean = false;
  isHkdfKeyCompressed: boolean = false;
  symmetricAlgorithm: SymmetricAlgorithm = "aes-256-gcm";
  symmetricNonceLength: NonceLength = 16;
}

export const ECIES_CONFIG = new Config();

For example, if you set isEphemeralKeyCompressed = true, the payload would be like: 33 Bytes + AES instead of 65 Bytes + AES.

If you set isHkdfKeyCompressed = true, the hkdf key would be derived from ephemeral public key (compressed) + shared public key (compressed) instead of ephemeral public key (uncompressed) + shared public key (uncompressed).

If you set symmetricAlgorithm = "xchacha20", plaintext data will encrypted with XChacha20-Poly1305.

If you set symmetricNonceLength = 12, then the nonce of aes-256-gcm would be 12 bytes. XChacha20-Poly1305's nonce is always 24 bytes.

For compatibility, make sure different applications share the same configuration.

Changelog

See CHANGELOG.md.