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k3s/pkg/authenticator/hash/scrypt.go

89 lines
1.8 KiB

package hash
import (
"crypto/rand"
"crypto/subtle"
"encoding/base64"
"errors"
"fmt"
"golang.org/x/crypto/scrypt"
)
// Version is the hashing format version
const Version = 1
const hashFormat = "$%d:%x:%d:%d:%d:%s"
// SCrypt contains all of the variables needed for scrypt hashing
type SCrypt struct {
N int
R int
P int
KeyLen int
SaltLen int
}
// NewSCrypt returns a scrypt hasher with recommended default values
func NewSCrypt() Hasher {
return SCrypt{
N: 15,
R: 8,
P: 1,
KeyLen: 64,
SaltLen: 8,
}
}
// CreateHash will return a hashed version of the secretKey, or an error
func (s SCrypt) CreateHash(secretKey string) (string, error) {
salt := make([]byte, s.SaltLen)
_, err := rand.Read(salt)
if err != nil {
return "", err
}
dk, err := scrypt.Key([]byte(secretKey), salt, 1<<s.N, s.R, s.P, s.KeyLen)
if err != nil {
return "", err
}
enc := base64.RawStdEncoding.EncodeToString(dk)
hash := fmt.Sprintf(hashFormat, Version, salt, s.N, s.R, s.P, enc)
return hash, nil
}
// VerifyHash will compare a secretKey and a hash, and return nil if they match
func (s SCrypt) VerifyHash(hash, secretKey string) error {
var (
version, n uint
r, p int
enc string
salt []byte
)
_, err := fmt.Sscanf(hash, hashFormat, &version, &salt, &n, &r, &p, &enc)
if err != nil {
return err
}
if version != Version {
return fmt.Errorf("hash version %d does not match package version %d", version, Version)
}
dk, err := base64.RawStdEncoding.DecodeString(enc)
if err != nil {
return err
}
verify, err := scrypt.Key([]byte(secretKey), salt, 1<<n, r, p, len(dk))
if err != nil {
return err
}
if subtle.ConstantTimeCompare(dk, verify) != 1 {
return errors.New("hash does not match")
}
return nil
}