// RFC 4357 VKO GOST R 34.10-2001 key agreement function.
// UKM is user keying material, also called VKO-factor.
func (prv *PrivateKey) KEK2001(pub *PublicKey, ukm *big.Int) ([]byte, error) {
- if prv.Mode != Mode2001 {
- return nil, errors.New("gogost/gost3410: KEK2001 can not be used in Mode2012")
+ if prv.C.PointSize() != 32 {
+ return nil, errors.New("gogost/gost3410: KEK2001 is only for 256-bit curves")
}
key, err := prv.KEK(pub, ukm)
if err != nil {
return nil, err
}
h := gost341194.New(&gost28147.SboxIdGostR341194CryptoProParamSet)
- h.Write(key)
+ if _, err = h.Write(key); err != nil {
+ return nil, err
+ }
return h.Sum(key[:0]), nil
}