User Password Hashing in Go With the Bcrypt Package: A Guideline

Hashing user passwords in Go can be done using the golang.org/x/crypto/bcrypt package. The bcrypt package is widely used and trusted for securely hashing passwords.

Example: Hashing and Comparing Passwords in Go

1. Install the bcrypt package: If you don't have it installed already, you can get the package by running:

go get golang.org/x/crypto/bcrypt

2. Hashing and Comparing Passwords: Below is the Go code to hash and compare passwords.

Example Code:

package main

import (
    "fmt"
    "log"

    "golang.org/x/crypto/bcrypt"
)

// HashPassword hashes the given plain password using bcrypt
func HashPassword(password string) (string, error) {
    // The cost is the number of hashing rounds to perform. The default cost is 10.
    // A higher cost increases the computational time needed to hash (and therefore crack) the password.
    cost := 10
    
    hashedPassword, err := bcrypt.GenerateFromPassword([]byte(password), cost)
    if err != nil {
        return "", err
    }

    return string(hashedPassword), nil
}

// ComparePasswords compares a hashed password with a plain password.
// Returns true if they match, otherwise false.
func ComparePasswords(hashedPassword, plainPassword string) bool {
    err := bcrypt.CompareHashAndPassword([]byte(hashedPassword), []byte(plainPassword))
    return err == nil
}

func main() {
    plainPassword := "mySecurePassword123"

    // Hash the password
    hashedPassword, err := HashPassword(plainPassword)
    if err != nil {
        log.Fatalf("Error hashing password: %v", err)
    }
    fmt.Println("Hashed Password:", hashedPassword)

    // Compare the passwords
    isMatch := ComparePasswords(hashedPassword, plainPassword)
    fmt.Println("Do the passwords match?", isMatch)
}

Explanation:

1. Install the bcrypt Package: Ensure you have golang.org/x/crypto/bcrypt imported in your Go application.

2. HashPassword Function:

   • bcrypt.GenerateFromPassword([]byte(password), cost): This function hashes the given password using the specified cost factor (number of rounds). The cost factor affects the computational complexity of hashing.
   • The function returns the hashed password or an error if something goes wrong.

3. ComparePasswords Function:

   • bcrypt.CompareHashAndPassword([]byte(hashedPassword), []byte(plainPassword)): This function compares the hashed password with the plain password. It returns nil if they match, and an error otherwise.
   • The function returns true if the passwords match, and false otherwise.

4. Example Usage in main Function:

   • The plainPassword is hashed using HashPassword.
   • The hashed password is then compared with the plain password using ComparePasswords.

Security Considerations:

• Never Store Plain Text Passwords: Always hash passwords before storing them in your database.
• Use a Strong Cost Factor: The cost factor should be set high enough to make brute-force attacks impractical but not so high as to affect performance excessively. Generally, a value around 10 is a good default.
• Handle Errors Properly: Proper error handling should be in place to deal with any issues that might arise during the hashing or comparison process.
• Secure the Environment: Ensure that your server and database are secured against unauthorized access.

This approach ensures that user passwords are securely hashed and stored, providing a robust level of security for your application in Go.