storedpassword

Documentation

Overview

API that tries to make it safe(r) to store user's passwords

Index

• Variables
• func BuiltinStrategies(id string) (DerivationStrategy, DerivationStrategy)
• type DerivationStrategy
• type StoredPassword
  • func Store(plaintext string, strategy DerivationStrategy) (StoredPassword, error)
  • func Verify(stored StoredPassword, givenPlaintext string, resolver StrategyResolver) (StoredPassword, error)
• type StrategyResolver

Variables

var CurrentBestDerivationStrategy = builtinStrategies["pbkdf2-sha256-100k"]

provide this to Store() to automatically keep newly generated passwords up-to-date according to current recommendations

var ErrIncorrectPassword = errors.New("incorrect password")

Functions

func BuiltinStrategies

func BuiltinStrategies(id string) (DerivationStrategy, DerivationStrategy)

this works as a StrategyResolver to Verify()

Types

type DerivationStrategy

type DerivationStrategy interface {
	Id() string
	Derive(plaintext []byte, salt []byte) []byte
}

type StoredPassword

type StoredPassword string

format: $<strategyId>$<salt>$<derived> trying to be somewhat compatible with https://passlib.readthedocs.io/en/stable/modular_crypt_format.html#application-defined-hashes

with the exception that we're storing the cost in the <strategyId> so that we don't have to implement different parsing formats per strategy

func Store

func Store(plaintext string, strategy DerivationStrategy) (StoredPassword, error)

transforms a password into a form that is safe to store in a database, provided that you pass CurrentBestDerivationStrategy as the strategy.

func Verify

func Verify(stored StoredPassword, givenPlaintext string, resolver StrategyResolver) (StoredPassword, error)

1st return: if != "" is the upgraded version of the stored password, if upgraded DerivationStrategy found 2nd return: nil if hash matches and no internal errors occurred. ErrIncorrectPassword if no internal errors but hash doesn't match.

this function is safe from timing attacks

type StrategyResolver

type StrategyResolver func(id string) (found DerivationStrategy, upgrade DerivationStrategy)

both returns MUST NOT refer to same derivation strategy, so upgrade is nil if stored password is already succicient