passlock

README

Passlock

Slightly more secure than bcrypt alone. Consider this an alternative to "peppering".

Why?

1. Bcrypt cuts off anything longer than 72 characters.
2. Some implementations (not Go's however) get freaked out by NUL bytes.

They get freaked out by NUL bytes? Who cares?

Some people don't think bcrypt is enough, so they'll "pepper" the user's password by keyed-hashing it before bcrypting it. This is problematic because the hash function can produce NUL bytes. This can be solved by base64 (or hex even) encoding the hash output (which is what I do in this lib), but there's still the issue of having to get user's to reset their password if you want to change the key for the hash.

Usage

package main

import "github.com/bentranter/passlock"

func main() {
	// Your plaintext password
	password := []byte("password")

	// Get a key
	key := passlock.NewEncryptionKey()

	// Store the password
	encryptedPassword, err := passlock.GenerateFromPassword(password, passlock.DefaultCost, key)
	if err != nil {
		println(err)
	}

	// Retrieve the password
	err = passlock.CompareHashAndPassword(encryptedPassword, password, key)
	if err != nil {
		println(err)
		return
	}

	// We're going to rotate keys -- let's start by making a new key
	newKey := passlock.NewEncryptionKey()

	// Rotate the keys
	newEncryptedPassword, err := passlock.RotateKey(key, newKey, encryptedPassword)
	if err != nil {
		println(err)
		return
	}

	// See if that password matches with the new key
	err = passlock.CompareHashAndPassword(newEncryptedPassword, password, newKey)
	if err != nil {
		println(err)
		return
	}

	println("Passwords matched!")
	// Output: Passwords matched!
}

License

MIT. See the license file for more info.

Inspired by password_lock.

Encryption code taken from cryptopasta.

Documentation

Overview

Package passlock stores your passwords a tiny bit more safely than bcrypt alone.

Example

// Your plaintext password
password := []byte("password")

// Get a key
key := NewEncryptionKey()

// Store the password
encryptedPassword, err := GenerateFromPassword(password, DefaultCost, key)
if err != nil {
	fmt.Println(err)
}

// Retrieve the password
err = CompareHashAndPassword(encryptedPassword, password, key)
if err != nil {
	fmt.Println(err)
	return
}

// We're going to rotate keys -- let's start by making a new key
newKey := NewEncryptionKey()

// Rotate the keys
newEncryptedPassword, err := RotateKey(key, newKey, encryptedPassword)
if err != nil {
	fmt.Println(err)
	return
}

// See if that password matches with the new key
err = CompareHashAndPassword(newEncryptedPassword, password, newKey)
if err != nil {
	fmt.Println(err)
	return
}

fmt.Println("Passwords matched!")

Output:

Passwords matched!

Index

• Constants
• func CompareHashAndPassword(encryptedPassword, password []byte, key *[32]byte) error
• func GenerateFromPassword(password []byte, cost int, key *[32]byte) ([]byte, error)
• func NewEncryptionKey() *[32]byte
• func RotateKey(oldKey, newKey *[32]byte, encryptedPassword []byte) ([]byte, error)

Examples

• Package

Constants

const DefaultCost = 14

DefaultCost is the minimum work factor for bcrypt.

Functions

func CompareHashAndPassword

func CompareHashAndPassword(encryptedPassword, password []byte, key *[32]byte) error

CompareHashAndPassword compares a hashed password to a plaintext password. It will return nil if the passwords match, and an error otherwise.

This package wraps all the errors exported by the bcrypt package, so you won't need to import that package to compare errors.

func GenerateFromPassword

func GenerateFromPassword(password []byte, cost int, key *[32]byte) ([]byte, error)

GenerateFromPassword hashes and salts a password from the given plaintext password and HMAC key.

func NewEncryptionKey

func NewEncryptionKey() *[32]byte

NewEncryptionKey generates a random 256-bit key for Encrypt() and Decrypt(). It panics if the source of randomness fails.

func RotateKey

func RotateKey(oldKey, newKey *[32]byte, encryptedPassword []byte) ([]byte, error)

RotateKey decrypts the given hash using the old key, and encrypts it with the new one.