passlib for go
Python's passlib is quite an amazing
library. I'm not sure there's a password library in existence with more thought
put into it, or with more support for obscure password formats.
This is a skeleton of a port of passlib to Go. It dogmatically adopts the
modular crypt format, which passlib has excellent documentation for.
Currently, it supports:
- Argon2i
- scrypt-sha256
- sha512-crypt
- sha256-crypt
- bcrypt
- passlib's bcrypt-sha256 variant
- pbkdf2-sha512 (in passlib format)
- pbkdf2-sha256 (in passlib format)
- pbkdf2-sha1 (in passlib format)
By default, it will hash using scrypt-sha256 and verify existing hashes using
any of these schemes.
Example Usage
There's a default context for ease of use. Most people need only concern
themselves with the functions Hash and Verify:
// Hash a plaintext, UTF-8 password.
func Hash(password string) (hash string, err error)
// Verifies a plaintext, UTF-8 password using a previously derived hash.
// Returns non-nil err if verification fails.
//
// Also returns an upgraded password hash if the hash provided is
// deprecated.
func Verify(password, hash string) (newHash string, err error)
Here's a rough skeleton of typical usage.
import "gopkg.in/hlandau/passlib.v1"
func RegisterUser() {
(...)
password := get a (UTF-8, plaintext) password from somewhere
hash, err := passlib.Hash(password)
if err != nil {
// couldn't hash password for some reason
return
}
(store hash in database, etc.)
}
func CheckPassword() bool {
password := get the password the user entered
hash := the hash you stored from the call to Hash()
newHash, err := passlib.Verify(password, hash)
if err != nil {
// incorrect password, malformed hash, etc.
// either way, reject
return false
}
// The context has decided, as per its policy, that
// the hash which was used to validate the password
// should be changed. It has upgraded the hash using
// the verified password.
if newHash != "" {
(store newHash in database, replacing old hash)
}
return true
}
scrypt Modular Crypt Format
Since scrypt does not have a pre-existing modular crypt format standard, I made one. It's as follows:
$s2$N$r$p$salt$hash
...where N, r and p are the respective difficulty parameters to scrypt as positive decimal integers without leading zeroes, and salt and hash are base64-encoded binary strings. Note that the RFC 4648 base64 encoding is used (not the one used by sha256-crypt and sha512-crypt).
Licence
passlib is partially derived from Python's passlib and so maintains its BSD license.
© 2008-2012 Assurance Technologies LLC. (Python passlib) BSD License
© 2014 Hugo Landau <hlandau@devever.net> BSD License