UserSchema.pre('save', function(next) {
  var user = this;

  var salt = crypto.randomBytes(128).toString('base64');
  crypto.pbkdf2(user.password, salt, 10000, 512, function(err, derivedKey) {
    user.password = derivedKey;
    next();
  });
});

UserSchema.methods.validPassword = function(password) {
  // need to salt and hash this password I think to compare
  // how to I get the salt?
}

function hashPassword(password) {
    var salt = crypto.randomBytes(128).toString('base64');
    var iterations = 10000;
    var hash = pbkdf2(password, salt, iterations);

    return {
        salt: salt,
        hash: hash,
        iterations: iterations
    };
}

function isPasswordCorrect(savedHash, savedSalt, savedIterations, passwordAttempt) {
    return savedHash == pbkdf2(passwordAttempt, savedSalt, savedIterations);
}

var bcrypt = require('bcrypt');
var salt = bcrypt.genSaltSync(10);
var hash = bcrypt.hashSync("B4c0//", salt);
// Store hash in your password DB.

// Load hash from your password DB.
bcrypt.compareSync("B4c0//", hash); // true
bcrypt.compareSync("not_bacon", hash); // false

import * as crypto from 'crypto';

const PASSWORD_LENGTH = 256;
const SALT_LENGTH = 64;
const ITERATIONS = 10000;
const DIGEST = 'sha256';
const BYTE_TO_STRING_ENCODING = 'hex'; // this could be base64, for instance

/**
 * The information about the password that is stored in the database
 */
interface PersistedPassword {
    salt: string;
    hash: string;
    iterations: number;
}

/**
 * Generates a PersistedPassword given the password provided by the user. This should be called when creating a user
 * or redefining the password
 */
export async function generateHashPassword(password: string): Promise<PersistedPassword> {
    return new Promise<PersistedPassword>((accept, reject) => {
        const salt = crypto.randomBytes(SALT_LENGTH).toString(BYTE_TO_STRING_ENCODING);
        crypto.pbkdf2(password, salt, ITERATIONS, PASSWORD_LENGTH, DIGEST, (error, hash) => {
            if (error) {
                reject(error);
            } else {
                accept({
                    salt,
                    hash: hash.toString(BYTE_TO_STRING_ENCODING),
                    iterations: ITERATIONS,
                });
            }
        });
    });
}

/**
 * Verifies the attempted password against the password information saved in the database. This should be called when
 * the user tries to log in.
 */
export async function verifyPassword(persistedPassword: PersistedPassword, passwordAttempt: string): Promise<boolean> {
    return new Promise<boolean>((accept, reject) => {
        crypto.pbkdf2(passwordAttempt, persistedPassword.salt, persistedPassword.iterations, PASSWORD_LENGTH, DIGEST, (error, hash) => {
            if (error) {
                reject(error);
            } else {
                accept(persistedPassword.hash === hash.toString(BYTE_TO_STRING_ENCODING));
            }
        });
    });
}