@tiny-utils/crypto/src/asymmetric.ts

Tiny utils for crypto: asymmetric/symmetric encryption, ed25519, sha256, etc.

import { packSymmetricalyEncryptedData, unpackSymmetricalyEncryptedData } from './symmetric';

import { randomBytes, box as naclbox } from 'tweetnacl';

/**
 * @category Crypto
 * @description Method to get public key from private key using *x25519* algorithm.
 *
 * @param privateKey Private key
 * @returns Public key
 */
export const publicKeyFromPrivateKey = (privateKey: Uint8Array) => {
	return naclbox.keyPair.fromSecretKey(privateKey).publicKey;
};

/**
 * @category Crypto
 * @description Method to asymmetrically encrypt the data using *x25519-xsalsa20-poly1305* algorithm.
 *
 * @param data Data to encrypt
 * @param mySecretKey My private key
 * @param theirPublicKey Recipient's public key
 * @returns Encrypted data
 */
export const asymmetricEncrypt = (data: Uint8Array, mySecretKey: Uint8Array, theirPublicKey: Uint8Array) => {
	const nonce = randomBytes(24);
	const encData = naclbox(data, nonce, theirPublicKey, mySecretKey);
	return packSymmetricalyEncryptedData(encData, nonce);
};

/**
 * @category Crypto
 * @description Method to asymmetrically decrypt the data using *x25519-xsalsa20-poly1305* algorithm.
 *
 * @param data Data to decrypt
 * @param mySecretKey My private key
 * @param theirPublicKey Sender's public key
 * @returns Decrypted data
 */
export const asymmetricDecrypt = (data: Uint8Array, mySecretKey: Uint8Array, theirPublicKey: Uint8Array) => {
	const { nonce, encData } = unpackSymmetricalyEncryptedData(data);

	const decData = naclbox.open(encData, nonce, theirPublicKey, mySecretKey);
	if (!decData) {
		throw new Error(`asymmetricDecrypt: Invalid box or key`);
	}
	return decData;
};