Add common cypherpunks.ru prefix for govpn Go package names

[govpn.git] / src / cypherpunks.ru / govpn / encless.go

diff --git a/src/cypherpunks.ru/govpn/encless.go b/src/cypherpunks.ru/govpn/encless.go
new file mode 100644 (file)
index 0000000..30eb4a5
--- /dev/null
+++ b/src/cypherpunks.ru/govpn/encless.go
@@ -0,0 +1,71 @@
+/*
+GoVPN -- simple secure free software virtual private network daemon
+Copyright (C) 2014-2016 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, 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 <http://www.gnu.org/licenses/>.
+*/
+
+package govpn
+
+import (
+       "cypherpunks.ru/govpn/aont"
+       "cypherpunks.ru/govpn/cnw"
+)
+
+const (
+       EnclessEnlargeSize = aont.HSize + aont.RSize*cnw.EnlargeFactor
+)
+
+// Confidentiality preserving (but encryptionless) encoding.
+//
+// It uses Chaffing-and-Winnowing technology (it is neither
+// encryption nor steganography) over All-Or-Nothing-Transformed data.
+// nonce is 64-bit nonce. Output data will be EnclessEnlargeSize larger.
+// It also consumes 64-bits of entropy.
+func EnclessEncode(authKey *[32]byte, nonce, in []byte) ([]byte, error) {
+       r := new([aont.RSize]byte)
+       var err error
+       if _, err = Rand.Read(r[:]); err != nil {
+               return nil, err
+       }
+       aonted, err := aont.Encode(r, in)
+       if err != nil {
+               return nil, err
+       }
+       out := append(
+               cnw.Chaff(authKey, nonce, aonted[:aont.RSize]),
+               aonted[aont.RSize:]...,
+       )
+       SliceZero(aonted[:aont.RSize])
+       return out, nil
+}
+
+// Decode EnclessEncode-ed data.
+func EnclessDecode(authKey *[32]byte, nonce, in []byte) ([]byte, error) {
+       var err error
+       winnowed, err := cnw.Winnow(
+               authKey, nonce, in[:aont.RSize*cnw.EnlargeFactor],
+       )
+       if err != nil {
+               return nil, err
+       }
+       out, err := aont.Decode(append(
+               winnowed, in[aont.RSize*cnw.EnlargeFactor:]...,
+       ))
+       SliceZero(winnowed)
+       if err != nil {
+               return nil, err
+       }
+       return out, nil
+}