summaryrefslogtreecommitdiff
path: root/src/keyDerivation.cpp
blob: 12ba5d85ec612795e983d1739c032d91fcad776a (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 "log.h"
#include "keyDerivation.h"
#include "mpi.h"
#include "threadUtils.hpp"

#include <stdexcept>
#include <iostream>
#include <string>

#include <gcrypt.h>


void KeyDerivation::setLogKDRate(const uint8_t log_rate)
{
  Lock lock(mutex_);
  if( log_rate < 49 )
    ld_kdr_ = log_rate;
}

//****** NullKeyDerivation ******

void NullKeyDerivation::generate(satp_prf_label label, seq_nr_t seq_nr, Buffer& key)
{
  for(u_int32_t i=0; i < key.getLength(); ++i) key[i] = 0;
}

//****** AesIcmKeyDerivation ******

AesIcmKeyDerivation::~AesIcmKeyDerivation()
{
  Lock lock(mutex_);
  if(cipher_)
    gcry_cipher_close( cipher_ );
}

void AesIcmKeyDerivation::updateMasterKey()
{
  if(!cipher_)
    return;

  gcry_error_t err = gcry_cipher_setkey( cipher_, master_key_.getBuf(), master_key_.getLength() );
  if( err ) {
    char buf[STERROR_TEXT_MAX];
    buf[0] = 0;
    cLog.msg(Log::PRIO_ERR) << "KeyDerivation::updateMasterKey: Failed to set cipher key: " << gpg_strerror_r(err, buf, STERROR_TEXT_MAX);
  }
}

void AesIcmKeyDerivation::init(Buffer key, Buffer salt)
{
  Lock lock(mutex_);
  if(cipher_)
    gcry_cipher_close( cipher_ );

  // TODO: hardcoded size
  gcry_error_t err = gcry_cipher_open( &cipher_, GCRY_CIPHER_AES128, GCRY_CIPHER_MODE_CTR, 0 );
  if( err ) {
    char buf[STERROR_TEXT_MAX];
    buf[0] = 0;
    cLog.msg(Log::PRIO_ERR) << "KeyDerivation::init: Failed to open cipher: " << gpg_strerror_r(err, buf, STERROR_TEXT_MAX);
    return;
  }
  
  master_salt_ = SyncBuffer(salt);
  master_key_ = SyncBuffer(key);

  updateMasterKey();
}

void AesIcmKeyDerivation::generate(satp_prf_label label, seq_nr_t seq_nr, Buffer& key) 
{
  Lock lock(mutex_);
  if(!cipher_)
  {
    cLog.msg(Log::PRIO_ERR) << "KeyDerivation::generate: cipher not opened";
    return;
  }

  gcry_error_t err = gcry_cipher_reset( cipher_ );
  if( err ) {
    char buf[STERROR_TEXT_MAX];
    buf[0] = 0;
    cLog.msg(Log::PRIO_ERR) << "KeyDerivation::generate: Failed to reset cipher: " << gpg_strerror_r(err, buf, STERROR_TEXT_MAX);
  }

  // see at: http://tools.ietf.org/html/rfc3711#section-4.3
  // *  Let r = index DIV key_derivation_rate (with DIV as defined above).
  // *  Let key_id = <label> || r.
  // *  Let x = key_id XOR master_salt, where key_id and master_salt are
  //    aligned so that their least significant bits agree (right-
  //    alignment).
  //

  Mpi r(48); // ld(kdr) <= 48
  if( ld_kdr_ == -1 )    // means key_derivation_rate = 0
    r = 0;  // TODO: no new key should be generated if r == 0, except it is the first time
  else
  {
    Mpi seq(32);
    seq = seq_nr;
    Mpi rate(48);
    rate = 1;
    rate = rate.mul2exp(ld_kdr_);
    r = seq / rate;
  }
      // TODO: generate key only if index % r == 0, except it is the first time

  Mpi key_id(128);                                                   // TODO: hardcoded size
  Mpi l(128);                                                 // TODO: hardcoded size
  l = label;
  key_id = l.mul2exp(48) + r;

  Mpi salt(master_salt_.getBuf(), master_salt_.getLength());
  Mpi x(128);                                                        // TODO: hardcoded size
  x = key_id ^ salt;

  size_t written;
  u_int8_t *ctr_buf = x.mul2exp(16).getNewBuf(&written);         // TODO: hardcoded size
  err = gcry_cipher_setctr( cipher_ , ctr_buf, written );
  delete[] ctr_buf;

  if( err ) {
    char buf[STERROR_TEXT_MAX];
    buf[0] = 0;
    cLog.msg(Log::PRIO_ERR) << "KeyDerivation::generate: Failed to set CTR: " << gpg_strerror_r(err, buf, STERROR_TEXT_MAX);
  }

  for(u_int32_t i=0; i < key.getLength(); ++i) key[i] = 0;
  err = gcry_cipher_encrypt( cipher_, key, key.getLength(), NULL, 0);
  if( err ) {
    char buf[STERROR_TEXT_MAX];
    buf[0] = 0;
    cLog.msg(Log::PRIO_ERR) << "KeyDerivation::generate: Failed to generate cipher bitstream: " << gpg_strerror_r(err, buf, STERROR_TEXT_MAX);
  }
}