Encryption

evpkdf/evpkdf.go

@@ -0,0 +1,55 @@
+// Copyright (c) 2016 Tristan Colgate-McFarlane
+//
+// This file is part of evpkdf.
+//
+// radia 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.
+//
+// radia 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 radia.  If not, see <http://www.gnu.org/licenses/>.
+
+// Package evpkdf implements OpenSSL EVP Key derivation function, aiming to
+// be compatible with crypto-js default behaviour.
+package evpkdf
+
+import (
+	"bytes"
+	"hash"
+	"io"
+)
+
+//New creates a key derivation function that should match the EVP kdf in crypto-js, which, in turn
+// should be compatible with openssl's EVP kdf
+func New(hash func() hash.Hash, password []byte, salt []byte, keysize int, iterations int) []byte {
+	hasher := hash()
+	derivedKey := []byte{}
+	block := []byte{}
+
+	// Generate key
+	for len(derivedKey) < keysize {
+		if len(block) != 0 {
+			io.Copy(hasher, bytes.NewBuffer(block))
+		}
+		io.Copy(hasher, bytes.NewBuffer(password))
+		io.Copy(hasher, bytes.NewBuffer(salt))
+		block = hasher.Sum(nil)
+		hasher.Reset()
+
+		// Iterations
+		for i := 1; i < iterations; i++ {
+			io.Copy(hasher, bytes.NewBuffer(block))
+			block = hasher.Sum(nil)
+			hasher.Reset()
+		}
+
+		derivedKey = append(derivedKey, block...)
+	}
+	return derivedKey[0:keysize]
+}