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|
package scrypt
import (
"crypto/rand"
"encoding/hex"
"errors"
"fmt"
"io"
"os"
"slices"
)
/*
#define _XOPEN_SOURCE 700
#include <stdlib.h>
#include <scrypt-kdf.h>
*/
import "C"
const (
MinimumPasswordLength = 16
_SALT_MIN_LENGTH = 32
_DESIRED_LENGTH = 32
_N = 1 << 15
r = 8
p = 1
)
var (
ErrSaltTooSmall = errors.New("scrypt: salt is too small")
ErrInternal = errors.New("scrypt: internal error")
)
type HashInput struct{
Password []byte
Salt []byte
}
type CheckInput struct{
Password []byte
Salt []byte
Hash []byte
}
// Package scrypt implements the scrypt key derivation function as defined in
// Colin Percival's paper "Stronger Key Derivation via Sequential Memory-Hard
// Functions" (https://www.tarsnap.com/scrypt/scrypt.pdf).
//
//
// Key derives a key from the password, salt, and cost parameters, returning
// a byte slice of length keyLen that can be used as cryptographic key.
//
// N is a CPU/memory cost parameter, which must be a power of 2 greater than 1.
// r and p must satisfy r * p < 2³⁰. If the parameters do not satisfy the
// limits, the function returns a nil byte slice and an error.
//
// For example, you can get a derived key for e.g. AES-256 (which needs a
// 32-byte key) by doing:
//
// dk, err := scrypt.Key([]byte("some password"), salt, 32768, 8, 1, 32)
//
// The recommended parameters for interactive logins as of 2017 are N=32768, r=8
// and p=1. The parameters N, r, and p should be increased as memory latency and
// CPU parallelism increases; consider setting N to the highest power of 2 you
// can derive within 100 milliseconds. Remember to get a good random salt.
func scrypt(
password []byte,
salt []byte,
N int,
r int,
p int,
outlen int,
) ([]byte, error) {
passwordbuf := C.CBytes(password)
saltbuf := C.CBytes(salt)
defer C.free(passwordbuf)
defer C.free(saltbuf)
outbuf := C.malloc(C.size_t(outlen))
defer C.free(outbuf)
rv := C.scrypt_kdf(
(*C.uint8_t)(passwordbuf),
C.size_t(len(password)),
(*C.uint8_t)(saltbuf),
C.size_t(len(salt)),
C.uint64_t(N),
C.uint32_t(r),
C.uint32_t(p),
(*C.uint8_t)(outbuf),
C.size_t(outlen),
)
if rv != 0 {
return nil, ErrInternal
}
out := C.GoBytes(outbuf, C.int(outlen))
return out, nil
}
func Hash(input HashInput) ([]byte, error) {
if len(input.Salt) < _SALT_MIN_LENGTH {
return nil, ErrSaltTooSmall
}
hash, err := scrypt(
input.Password,
input.Salt,
_N,
r,
p,
_DESIRED_LENGTH,
)
return hash, err
}
func SaltFrom(r io.Reader) ([]byte, error) {
buffer := make([]byte, _SALT_MIN_LENGTH)
_, err := io.ReadFull(r, buffer)
if err != nil {
return nil, err
}
return buffer, nil
}
func Salt() ([]byte, error) {
return SaltFrom(rand.Reader)
}
func Check(input CheckInput) (bool, error) {
hashInput := HashInput{
Password: input.Password,
Salt: input.Salt,
}
candidate, err := Hash(hashInput)
if err != nil {
return false, err
}
return slices.Equal(candidate, input.Hash), nil
}
func Main() {
if len(os.Args) != 3 {
fmt.Fprintf(os.Stderr, "Usage: scrypt PASSWORD SALT\n")
os.Exit(2)
}
password := []byte(os.Args[1])
salt := []byte(os.Args[2])
input := HashInput{
Password: password,
Salt: salt,
}
payload, err := Hash(input)
if err != nil {
if err == ErrSaltTooSmall {
fmt.Fprintln(os.Stderr, err)
os.Exit(2)
}
panic(err)
}
fmt.Println(hex.EncodeToString(payload))
}
|
