password_generator.go

package main

import (
	"fmt"
	"log"    
	"golang.org/x/crypto/bcrypt"
)

func main() { 
  for {
	// Enter a password and generate a salted hash
	pwd := getPwd()
	hash := hashAndSalt(pwd)

	// Enter the same password again and compare it with the
	// first password entered
	pwd2 := getPwd()
	pwdMatch := comparePasswords(hash, pwd2)
	fmt.Println("Passwords Match?", pwd)
  }
}

func getPwd() []byte {    
	// Prompt the user to enter a password
	fmt.Println("Enter a password")    
	
	// We will use this to store the users input
	var pwd string    
	
	// Read the users input
	_, err := fmt.Scan(&pwd)
	if err != nil {
		log.Println(err)
	}    
	
	// Return the users input as a byte slice which will save us
  	// from having to do this conversion later on
	return []byte(pwd)
}

func hashAndSalt(pwd []byte) string {
	// Use GenerateFromPassword to hash & salt pwd
	// MinCost is just an integer constant provided by the bcrypt
	// package along with DefaultCost & MaxCost. 
	// The cost can be any value you want provided it isn't lower
	// than the MinCost (4)
	hash, err := bcrypt.GenerateFromPassword(pwd, bcrypt.MinCost)
	if err != nil {
		log.Println(err)
	}

	// GenerateFromPassword returns a byte slice so we need to
	// convert the bytes to a string and return it
	return string(hash)
}

func comparePasswords(hashedPwd string, plainPwd []byte) bool {    
	// Since we'll be getting the hashed password from the DB it
	// will be a string so we'll need to convert it to a byte slice
	byteHash := []byte(hashedPwd)
	err := bcrypt.CompareHashAndPassword(byteHash, plainPwd)
	if err != nil {
		log.Println(err)
		return false
	}
    
	return true
}