--- /dev/null
+// GoGOST -- Pure Go GOST cryptographic functions library
+// Copyright (C) 2015-2016 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, either version 3 of the License, or
+// (at your option) any later version.
+//
+// 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 (
+ "errors"
+ "math/big"
+
+ "cypherpunks.ru/gogost/gost28147"
+ "cypherpunks.ru/gogost/gost341194"
+)
+
+// 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("KEK2001 can not be used in Mode2012")
+ }
+ key, err := prv.KEK(pub, ukm)
+ if err != nil {
+ return nil, err
+ }
+ h := gost341194.New(&gost28147.GostR3411_94_CryptoProParamSet)
+ h.Write(key)
+ return h.Sum(key[:0]), nil
+}