auth.utils.ts

import { pbkdf2, randomBytes } from "crypto";

/**
 * Interface with all the necessary items related to the encryption
 */
export interface IEncryptedPassord {
	encryptedPassword: string;
	salt: string;
	iterations: number;
}

/**
 * Utils class to handle common operations to authenticate such as encrypt or decrypt a password
 */
export class AuthUtils {

	// --------------------------------------------------------
	// --------------------- Public methods -------------------
	// --------------------------------------------------------

	/**
	 * Encrypts the given password with hmac sha512, a 32bit salt and 20000 iterations and returns an object with:
	 * the result hash, the used salt and the number of iterations made
	 * @param password 
	 */
	public static encryptPassword(password: string): Promise<IEncryptedPassord> {
		let salt = randomBytes(this.SALT_BYTES).toString(this.STRING_GENERATOR);
		return this.encrypt(password, salt, this.ITERATIONS);
	}

	/**
	 * Checks if the given password matches the stored one
	 * @param password 
	 * @param storedPassword 
	 */
	public static checkPassword(password:string, storedPassword:IEncryptedPassord): Promise<boolean> {
		return this.encrypt(password, storedPassword.salt, storedPassword.iterations).then((resultEnc)=> {
			return resultEnc.encryptedPassword === storedPassword.encryptedPassword;
		}).catch((err) => {
			console.log(err);
			return false;
		});
	}

	// --------------------------------------------------------
	// -------------------- Private methods -------------------
	// --------------------------------------------------------

	/**
	 * Encrypts the given password with the salt and iterations provided
	 * @param password 
	 * @param salt 
	 * @param iterations 
	 */
	private static encrypt(password: string, salt: string, iterations: number): Promise<IEncryptedPassord> {
		return new Promise<IEncryptedPassord>((resolve, reject) => {

			pbkdf2(password, salt, iterations, this.KEYLEN, this.DIGEST, (err, key) => {
				if (err) { reject(err) }
				else { 
					let result: IEncryptedPassord = {
						encryptedPassword: key.toString(this.STRING_GENERATOR),
						iterations: iterations,
						salt: salt
					};
					resolve(result);
				}
			});

		});
	}

	// --------------------------------------------------------
	// ------------------- Private constants ------------------
	// --------------------------------------------------------

	private static readonly ITERATIONS: number = 20000;
	private static readonly SALT_BYTES: number = 32;
	private static readonly STRING_GENERATOR: string = 'hex';
	private static readonly KEYLEN: number = 512;
	private static readonly DIGEST: string = 'sha512';

}