index.ts

/** @format */

import "./ensureBuffer";
import sjcl from "sjcl";

type Callback = (err?: Error, buff?: Buffer) => any;

function cbWarnError(err: Error, _: Buffer = null): void {
	if (err) {
		console.warn("Error in react-native-randombytes", err);
	}
}

function generateEntropy(): void {
	if (sjcl.random.isReady()) {
		return;
	} else {
		setTimeout(() => {
			try {
				const now = Date.now();
				sjcl.random.addEntropy(now, 2, "random-bytes-pure.generateEntropy");
				generateEntropy();
			} catch (e) {
				cbWarnError(e);
			}
		}, 1);
	}
}

export function randomBytes(length, cb: Callback = cbWarnError) {
	try {
		const wordCount = Math.ceil(length * 0.25);
		const randomBytes = sjcl.random.randomWords(wordCount);
		const hexString = sjcl.codec.hex
			.fromBits(randomBytes)
			.substr(0, length * 2);
		const toReturn = Buffer.from(hexString, "hex");
		cb(null, toReturn);
		return toReturn;
	} catch (e) {
		cb(e);
		throw e;
	}
}

export default randomBytes;

try {
	sjcl.random.addEventListener("progress", generateEntropy);
	generateEntropy();
} catch (e) {
	cbWarnError(e);
	throw e;
}