authelia/authentication/password_hash.go
Clement Michaud 828f565290 Bootstrap Go implementation of Authelia.
This is going to be the v4.

Expected improvements:
- More reliable due to static typing.
- Bump of performance.
- Improvement of logging.
- Authelia can be shipped as a single binary.
- Will likely work on ARM architecture.
2019-10-28 23:28:59 +01:00

102 lines
2.6 KiB
Go

package authentication
// #cgo LDFLAGS: -lcrypt
// #define _GNU_SOURCE
// #include <crypt.h>
// #include <stdlib.h>
import "C"
import (
"errors"
"fmt"
"math/rand"
"strconv"
"strings"
"unsafe"
)
// Crypt wraps C library crypt_r
func crypt(key string, salt string) string {
data := C.struct_crypt_data{}
ckey := C.CString(key)
csalt := C.CString(salt)
out := C.GoString(C.crypt_r(ckey, csalt, &data))
C.free(unsafe.Pointer(ckey))
C.free(unsafe.Pointer(csalt))
return out
}
// PasswordHash represents all characteristics of a password hash.
// Authelia only supports salted SHA512 method, i.e., $6$ mode.
type PasswordHash struct {
// The number of rounds.
Rounds int
// The salt with a max size of 16 characters for SHA512.
Salt string
// The password hash.
Hash string
}
// passwordHashFromString extracts all characteristics of a hash given its string representation.
func passwordHashFromString(hash string) (*PasswordHash, error) {
// Only supports salted sha 512.
if hash[:3] != "$6$" {
return nil, errors.New("Authelia only supports salted SHA512 hashing")
}
parts := strings.Split(hash, "$")
if len(parts) != 5 {
return nil, errors.New("Cannot parse the hash")
}
roundsKV := strings.Split(parts[2], "=")
if len(roundsKV) != 2 {
return nil, errors.New("Cannot find the number of rounds")
}
rounds, err := strconv.ParseInt(roundsKV[1], 10, 0)
if err != nil {
return nil, fmt.Errorf("Cannot find the number of rounds in the hash: %s", err.Error())
}
return &PasswordHash{
Rounds: int(rounds),
Salt: parts[3],
Hash: parts[4],
}, nil
}
// The set of letters RandomString can pick in.
var possibleLetters = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")
// RandomString generate a random string of n characters.
func RandomString(n int) string {
b := make([]rune, n)
for i := range b {
b[i] = possibleLetters[rand.Intn(len(possibleLetters))]
}
return string(b)
}
// HashPassword generate a salt and hash the password with the salt and a constant
// number of rounds.
func HashPassword(password string, salt *string) string {
var generatedSalt string
if salt == nil {
generatedSalt = fmt.Sprintf("$6$rounds=5000$%s$", RandomString(16))
} else {
generatedSalt = *salt
}
return crypt(password, generatedSalt)
}
// CheckPassword check a password against a hash.
func CheckPassword(password string, hash string) (bool, error) {
passwordHash, err := passwordHashFromString(hash)
if err != nil {
return false, err
}
salt := fmt.Sprintf("$6$rounds=%d$%s$", passwordHash.Rounds, passwordHash.Salt)
pHash := HashPassword(password, &salt)
return pHash == hash, nil
}