-
Notifications
You must be signed in to change notification settings - Fork 0
/
vko.go
36 lines (33 loc) · 1.13 KB
/
vko.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
// GoGOST -- Pure Go GOST cryptographic functions library
// Copyright (C) 2015-2021 Sergey Matveev <stargrave@stargrave.org>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, version 3 of the License.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package gost3410
import (
"math/big"
)
func (prv *PrivateKey) KEK(pub *PublicKey, ukm *big.Int) ([]byte, error) {
keyX, keyY, err := prv.C.Exp(prv.Key, pub.X, pub.Y)
if err != nil {
return nil, err
}
u := big.NewInt(0).Set(ukm).Mul(ukm, prv.C.Co)
if u.Cmp(bigInt1) != 0 {
keyX, keyY, err = prv.C.Exp(u, keyX, keyY)
if err != nil {
return nil, err
}
}
pk := PublicKey{prv.C, keyX, keyY}
return pk.Raw(), nil
}