2 GoVPN -- simple secure free software virtual private network daemon
3 Copyright (C) 2014-2016 Sergey Matveev <stargrave@stargrave.org>
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation, either version 3 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>.
27 EncLessEnlargeSize = aont.HSize + aont.RSize*chaffing.EnlargeFactor
30 // Confidentiality preserving (but encryptionless) encoding.
32 // It uses Chaffing-and-Winnowing technology (it is neither
33 // encryption nor steganography) over All-Or-Nothing-Transformed data.
34 // nonce is 64-bit nonce. Output data will be EncLessEnlargeSize larger.
35 // It also consumes 64-bits of entropy.
36 func EncLessEncode(authKey *[32]byte, nonce, in []byte) ([]byte, error) {
37 r := new([aont.RSize]byte)
39 if _, err = Rand.Read(r[:]); err != nil {
42 aonted, err := aont.Encode(r, in)
47 chaffing.Chaff(authKey, nonce, aonted[:aont.RSize]),
48 aonted[aont.RSize:]...,
50 SliceZero(aonted[:aont.RSize])
54 // Decode EncLessEncode-ed data.
55 func EncLessDecode(authKey *[32]byte, nonce, in []byte) ([]byte, error) {
57 winnowed, err := chaffing.Winnow(
58 authKey, nonce, in[:aont.RSize*chaffing.EnlargeFactor],
63 out, err := aont.Decode(append(
64 winnowed, in[aont.RSize*chaffing.EnlargeFactor:]...,