hash-bcrypt.md

Hash Provider using Bcrypt

Install Bcrypt

npm i bcrypt

Create the Hashing Provider

Implement password hashing and comparison using the Bcrypt library.

// src/auth/providers/hashing.provider.ts
import { Injectable } from "@nestjs/common";
import * as bcrypt from "bcrypt";

@Injectable()
export class HashingProvider {
  // Hash the password
  public async hashPassword(data: string): Promise<string> {
    const salt = await bcrypt.genSalt(); // Generate the salt
    return bcrypt.hash(data, salt); // Hash password with salt
  }

  // Compare the password with the hash
  public async comparePassword(data: string, encrypted: string): Promise<boolean> {
    return bcrypt.compare(data, encrypted);
  }
}

• Generating a Salt: The bcrypt.genSalt() method creates a random salt that is added to the password before hashing. The salt ensures that even if two users have the same password, their hashes will be different.

• Hashing the Password: The bcrypt.hash() method takes the plain password and the generated salt, combining them to produce a unique hash.

• Password Comparison: The bcrypt.compare() method compares a plain-text password with a hashed password. If they match, it returns true, otherwise false.

• Bcrypt: Bcrypt provides built-in salt generation and hash comparison, reducing complexity and improving security.

Create User Provider

import { HashingProvider } from "src/auth/providers/hashing.provider";

// users/providers/create-user.provider.ts
@Injectable()
export class CreateUserProvider {
  constructor(private readonly hashingProvider: HashingProvider) {}

  public async createUser(createUserDto: CreateUserDto) {
    // ...

    const newUser = this.usersRepository.create({
      ...createUserDto,
      // Hash the user's password before saving to the database
      password: await this.hashingProvider.hashPassword(createUserDto.password),
    });

    // ...
  }
}

Hashing the Password: Before saving the user, we use hashingProvider.hashPassword() to securely hash the password.

Sign In Provider

// auth/providers/sign-in-provider.ts
import { HashingProvider } from "./hashing.provider";

@Injectable()
export class SignInProvider {
  constructor(private readonly hashingProvider: HashingProvider) {}

  public async signIn(signInDto: SignInDto) {
    // Find existing user by email
    const user = await this.usersService.findOneByEmail(signInDto.email);

    // Compare the input password to the hash
    const isPasswordEqual = await this.hashingProvider.comparePassword(
      signInDto.password,
      user.password
    );

    if (!isPasswordEqual) {
      throw new UnauthorizedException("Incorrect Password");
    }

    // Return JWT
    return "JWT";
  }
}