go.cypherpunks.ru namespace usage

[gogost.git] / gost34112012256 / kdf.go

diff --git a/gost34112012256/kdf.go b/gost34112012256/kdf.go
new file mode 100644 (file)
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+++ b/gost34112012256/kdf.go
@@ -0,0 +1,41 @@
+// GoGOST -- Pure Go GOST cryptographic functions library
+// Copyright (C) 2015-2019 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 gost34112012256
+
+import (
+       "crypto/hmac"
+       "hash"
+)
+
+type KDF struct {
+       h hash.Hash
+}
+
+func NewKDF(key []byte) *KDF {
+       return &KDF{hmac.New(New, key)}
+}
+
+func (kdf *KDF) Derive(dst, label, seed []byte) (r []byte) {
+       kdf.h.Write([]byte{0x01})
+       kdf.h.Write(label)
+       kdf.h.Write([]byte{0x00})
+       kdf.h.Write(seed)
+       kdf.h.Write([]byte{0x01})
+       kdf.h.Write([]byte{0x00})
+       r = kdf.h.Sum(dst)
+       kdf.h.Reset()
+       return r
+}