1 // GoGOST -- Pure Go GOST cryptographic functions library
2 // Copyright (C) 2015-2023 Sergey Matveev <stargrave@stargrave.org>
4 // This program is free software: you can redistribute it and/or modify
5 // it under the terms of the GNU General Public License as published by
6 // the Free Software Foundation, version 3 of the License.
8 // This program is distributed in the hope that it will be useful,
9 // but WITHOUT ANY WARRANTY; without even the implied warranty of
10 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 // GNU General Public License for more details.
13 // You should have received a copy of the GNU General Public License
14 // along with this program. If not, see <http://www.gnu.org/licenses/>.
23 "go.cypherpunks.ru/gogost/v5/gost28147"
24 "go.cypherpunks.ru/gogost/v5/gost341194"
27 // RFC 4357 VKO GOST R 34.10-2001 key agreement function.
28 // UKM is user keying material, also called VKO-factor.
29 func (prv *PrivateKey) KEK2001(pub *PublicKey, ukm *big.Int) ([]byte, error) {
30 if prv.C.PointSize() != 32 {
31 return nil, errors.New("gogost/gost3410: KEK2001 is only for 256-bit curves")
33 key, err := prv.KEK(pub, ukm)
35 return nil, fmt.Errorf("gogost/gost3410.PrivateKey.KEK2001: %w", err)
37 h := gost341194.New(&gost28147.SboxIdGostR341194CryptoProParamSet)
38 if _, err = h.Write(key); err != nil {
39 return nil, fmt.Errorf("gogost/gost3410.PrivateKey.KEK2001: %w", err)
41 return h.Sum(key[:0]), nil