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package pwhash
import (
"crypto/pbkdf2"
"crypto/rand"
"crypto/sha512"
"crypto/subtle"
"errors"
)
const defaultIter = 12504615 // from tools/finditers
func HashIter(pw string, salt []byte, iter int) ([]byte, error) {
return pbkdf2.Key(sha512.New, pw, salt, iter, 32)
}
func Hash(pw string) ([]byte, error) {
buf := make([]byte, 40)
salt := buf[32:]
rand.Read(salt)
hash, err := HashIter(pw, salt, defaultIter)
if err != nil {
return nil, err
}
copy(buf, hash)
return buf, nil
}
var errBadPassword = errors.New("bad password")
func Check(pwHash []byte, pw string) error {
if len(pwHash) < 32 {
return errBadPassword
}
wantHash, salt := pwHash[:32], pwHash[32:]
gotHash, err := HashIter(pw, salt, defaultIter)
if err != nil {
return err
}
if subtle.ConstantTimeCompare(gotHash, wantHash) == 0 {
return errBadPassword
}
return nil
}
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