adding GPL

sshkeys/func.go

@@ -1,7 +1,24 @@
+/*
+   SSHSecure - a program to harden OpenSSH from defaults
+   Copyright (C) 2020  Brent Saner
+
+   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 <https://www.gnu.org/licenses/>.
+*/
+
 package sshkeys
 
 import (
-	"bytes"
 	"crypto/aes"
 	"crypto/cipher"
 	"crypto/rand"
@@ -143,6 +160,8 @@ func (k *SSHKeyV1) Generate(force bool) error {
 		k.KeySize = keyEd25519
 		k.BlockSize = blockEd25519
 	}
+	k.CipherName = CipherNull
+	k.KDFName = KdfNull
 	// Currently, OpenSSH has an option for multiple private keys. However, it is hardcoded to 1.
 	// If multiple key support is added in the future, will need to re-tool how I do this, perhaps, in the future. TODO.
 	pk := SSHPrivKey{
@@ -169,6 +188,30 @@ func (k *SSHKeyV1) Generate(force bool) error {
 	return nil
 }
 
-func (k *SSHKeyV1) build() {
+func (k *SSHKeyV1) build() error {
 	// We actually assemble the key buffer here. Translation to bytes where needed, case switches (ED25519 vs. RSA), etc.
+	k.Buffer.Truncate(0)
+	// First we need to do some prep for the common header.
+	kdfOptsBytes := []byte{}
+	switch k.(type) {
+	case EncryptedSSHKeyV1:
+		kdfOptsBytes = append(kdfOptsBytes, byte(len(k.KDFOpts.Salt)))
+	}
+	// For this, we can use a generic list and sequentially write.
+	cipher := []byte(k.CipherName)
+	kdf := []byte(k.KDFName)
+	commonHeader := [][]byte{
+		[]byte(KeyV1Magic + "\x00"),
+		{byte(len(cipher))},
+		cipher,
+		{byte(len(kdf))},
+		kdf,
+	}
+	for _, v := range commonHeader {
+		if _, err := k.Buffer.Write(v); err != nil {
+			k.Buffer.Truncate(0)
+			return err
+		}
+	}
+
 }