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vko2001.go
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vko2001.go
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// 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 (
"errors"
"math/big"
"github.com/Theo730/gogost/gost28147"
"github.com/Theo730/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.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)
if _, err = h.Write(key); err != nil {
return nil, err
}
return h.Sum(key[:0]), nil
}