Hasher generating different hashes for same password in loopback?

Question

I am using loopback hasher as

import { PasswordHasher } from './hash.password.bcryptjs';

This has a function generate hash

credentials.password = await this.passwordHasher.hashPassword(credentials.password);

I am giving input as pass@1010 for password for generate hash but it is generating different hash every time.But the hash for same string should be same.

Code for class

import { genSalt, hash } from 'bcryptjs';
import { compare } from 'bcryptjs';
import { inject } from '@loopback/core';
import { PasswordHasherBindings } from '../keys';

/**
 * Service HashPassword using module 'bcryptjs'.
 * It takes in a plain password, generates a salt with given
 * round and returns the hashed password as a string
 */
export type HashPassword = (
  password: string,
  rounds: number,
) => Promise<string>;
// bind function to `services.bcryptjs.HashPassword`
export async function hashPassword(
  password: string,
  rounds: number,
): Promise<string> {
  const salt = await genSalt(rounds);
  return await hash(password, salt);
}

export interface PasswordHasher<T = string> {
  hashPassword(password: T): Promise<T>;
  comparePassword(providedPass: T, storedPass: T): Promise<boolean>;
}

export class BcryptHasher implements PasswordHasher<string> {
  constructor(
    @inject(PasswordHasherBindings.ROUNDS)
    private readonly rounds: number,
  ) { }

  async hashPassword(password: string): Promise<string> {
    const salt = await genSalt(10);
    return await hash(password, salt);
  }

  async comparePassword(
    providedPass: string,
    storedPass: string,
  ): Promise<boolean> {
    const passwordIsMatched = await compare(providedPass, storedPass);
    return passwordIsMatched;
  }
}

Answer 1

The problem is that you use a new salt with each hash. If you want get stable hash, you need to generate the salt once then re-use it in next round.