summaryrefslogtreecommitdiff
path: root/src/cipher.cpp
blob: e98bc3b8e00a0b27e5e5d4365a1ae3275d7f6f16 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
/*
 *  anytun
 *
 *  The secure anycast tunneling protocol (satp) defines a protocol used
 *  for communication between any combination of unicast and anycast
 *  tunnel endpoints.  It has less protocol overhead than IPSec in Tunnel
 *  mode and allows tunneling of every ETHER TYPE protocol (e.g.
 *  ethernet, ip, arp ...). satp directly includes cryptography and
 *  message authentication based on the methodes used by SRTP.  It is
 *  intended to deliver a generic, scaleable and secure solution for
 *  tunneling and relaying of packets of any protocol.
 *
 *
 *  Copyright (C) 2007 anytun.org <satp@wirdorange.org>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2
 *  as published by the Free Software Foundation.
 *
 *  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 (see the file COPYING included with this
 *  distribution); if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <stdexcept>
#include <iostream>
#include <string>
#include <cstdio>
#include <gcrypt.h>

#include "cipher.h"
#include "mpi.h"
#include "log.h"


      // TODO: in should be const but does not work with getBuf() :(
void Cipher::encrypt(PlainPacket & in, EncryptedPacket & out, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux)
{
	u_int32_t len = cipher(in, in.getLength(), out.getPayload(), out.getPayloadLength(), seq_nr, sender_id, mux);
	out.setSenderId(sender_id);
	out.setSeqNr(seq_nr);
  out.setMux(mux);
	out.setPayloadLength(len);
}

      // TODO: in should be const but does not work with getBuf() :(
void Cipher::decrypt(EncryptedPacket & in, PlainPacket & out)
{
	u_int32_t len = decipher(in.getPayload() , in.getPayloadLength(), out, out.getLength(), in.getSeqNr(), in.getSenderId(), in.getMux());
	out.setLength(len);
}


//******* NullCipher *******

u_int32_t NullCipher::cipher(u_int8_t* in, u_int32_t ilen, u_int8_t* out, u_int32_t olen, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux)
{
	std::memcpy(out, in, (ilen < olen) ? ilen : olen);
  return (ilen < olen) ? ilen : olen;
}

u_int32_t NullCipher::decipher(u_int8_t* in, u_int32_t ilen, u_int8_t* out, u_int32_t olen, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux)
{
	std::memcpy(out, in, (ilen < olen) ? ilen : olen);
  return (ilen < olen) ? ilen : olen;
}


//****** AesIcmCipher ****** 

AesIcmCipher::AesIcmCipher() : cipher_(NULL)
{
      // TODO: hardcoded keysize
  gcry_error_t err = gcry_cipher_open( &cipher_, GCRY_CIPHER_AES128, GCRY_CIPHER_MODE_CTR, 0 );
  if( err )
    cLog.msg(Log::PRIO_CRIT) << "AesIcmCipher::AesIcmCipher: Failed to open cipher";
}


AesIcmCipher::~AesIcmCipher()
{
  if(cipher_)
    gcry_cipher_close( cipher_ );
}

void AesIcmCipher::setKey(Buffer& key)
{
  if(!cipher_)
    return;

  gcry_error_t err = gcry_cipher_setkey( cipher_, key.getBuf(), key.getLength() );
  if( err )
    cLog.msg(Log::PRIO_ERR) << "AesIcmCipher::setKey: Failed to set cipher key: " << gpg_strerror( err );
}

void AesIcmCipher::setSalt(Buffer& salt)
{
  salt_ = salt;
  if(!salt_[u_int32_t(0)])
    salt_[u_int32_t(0)] = 1; // TODO: this is a outstandingly ugly workaround
}

u_int32_t AesIcmCipher::cipher(u_int8_t* in, u_int32_t ilen, u_int8_t* out, u_int32_t olen, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux)
{
  calc(in, ilen, out, olen, seq_nr, sender_id, mux);
  return (ilen < olen) ? ilen : olen;
}

u_int32_t AesIcmCipher::decipher(u_int8_t* in, u_int32_t ilen, u_int8_t* out, u_int32_t olen, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux)
{
  calc(in, ilen, out, olen, seq_nr, sender_id, mux);
  return (ilen < olen) ? ilen : olen;
}

void AesIcmCipher::calc(u_int8_t* in, u_int32_t ilen, u_int8_t* out, u_int32_t olen, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux)
{
  if(!cipher_)
    return;

  gcry_error_t err = gcry_cipher_reset( cipher_ );
  if( err ) {
    cLog.msg(Log::PRIO_ERR) << "AesIcmCipher: Failed to reset cipher: " << gpg_strerror( err );
    return;
  }

  // set the IV ( = CTR)
  //==========================================================================
  //  //  where the 128-bit integer value IV SHALL be defined by the SSRC, the
  //  //  SRTP packet index i, and the SRTP session salting key k_s, as below.
  //  //
  //  //  IV = (k_s * 2^16) XOR (SSRC * 2^64) XOR (i * 2^16)
  //  //  sizeof(k_s) = 112 bit, random

  Mpi ctr(128);                                                // TODO: hardcoded size
  Mpi salt(salt_.getBuf(), salt_.getLength());
  Mpi sid_mux(32);
  sid_mux = sender_id;
  Mpi mux_mpi(32);
  mux_mpi = mux;
  sid_mux = sid_mux ^ mux_mpi.mul2exp(16);
  Mpi seq(32);
  seq = seq_nr;

  ctr = salt.mul2exp(16) ^ sid_mux.mul2exp(64) ^ seq.mul2exp(16);  // TODO: hardcoded size

  size_t written;
  u_int8_t *ctr_buf = ctr.getNewBuf(&written);             // TODO: hardcoded size
  err = gcry_cipher_setctr( cipher_, ctr_buf, written );        // TODO: hardcoded size 
  delete[] ctr_buf;
  if( err ) {
    cLog.msg(Log::PRIO_ERR) << "AesIcmCipher: Failed to set cipher CTR: " << gpg_strerror( err );
    return;
  }

  err = gcry_cipher_encrypt( cipher_, out, olen, in, ilen );
  if( err ) {
    cLog.msg(Log::PRIO_ERR) << "AesIcmCipher: Failed to generate cipher bitstream: " << gpg_strerror( err );
    return;
  }
}