summaryrefslogtreecommitdiff
path: root/src/authAlgo.cpp
blob: 80ee3ba0c14627ae3f557497e09e425d4f4f70cc (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
/*
 *  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) 2007-2008 Othmar Gsenger, Erwin Nindl, 
 *                          Christian Pointner <satp@wirdorange.org>
 *
 *  This file is part of Anytun.
 *
 *  Anytun is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 3 as
 *  published by the Free Software Foundation.
 *
 *  Anytun 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 anytun.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "authAlgo.h"
#include "log.h"
#include "buffer.h"
#include "encryptedPacket.h"

#include <iostream>
#include <cstring>

#include <gcrypt.h>

//****** NullAuthAlgo ******
void NullAuthAlgo::generate(EncryptedPacket& packet)
{
}

bool NullAuthAlgo::checkTag(EncryptedPacket& packet)
{
  return true;
}

u_int32_t NullAuthAlgo::getMaxLength()
{
  return MAX_LENGTH_;
}

//****** Sha1AuthAlgo ******

Sha1AuthAlgo::Sha1AuthAlgo() : ctx_(NULL)
{
  gcry_error_t err = gcry_md_open( &ctx_, GCRY_MD_SHA1, GCRY_MD_FLAG_HMAC );
  if( err )
    cLog.msg(Log::PRIO_CRIT) << "Sha1AuthAlgo::Sha1AuthAlgo: Failed to open message digest algo";
}

Sha1AuthAlgo::~Sha1AuthAlgo()
{
  if(ctx_)
    gcry_md_close( ctx_ );
}

void Sha1AuthAlgo::setKey(Buffer& key)
{
  if(!ctx_)
    return;

  gcry_error_t err = gcry_md_setkey( ctx_, key.getBuf(), key.getLength() );
  if( err ) {
    char buf[STERROR_TEXT_MAX];
    buf[0] = 0;
    cLog.msg(Log::PRIO_ERR) << "Sha1AuthAlgo::setKey: Failed to set cipher key: " << gpg_strerror_r(err, buf, STERROR_TEXT_MAX);
  }
}

void Sha1AuthAlgo::generate(EncryptedPacket& packet)
{
  if(!packet.getAuthTagLength())
    return;

  gcry_md_reset( ctx_ );

  gcry_md_write( ctx_, packet.getAuthenticatedPortion(), packet.getAuthenticatedPortionLength() );
  gcry_md_final( ctx_ );

  u_int8_t* tag = packet.getAuthTag();
  if(packet.getAuthTagLength() > MAX_LENGTH_)
    std::memset(tag, 0, (packet.getAuthTagLength() - MAX_LENGTH_));
  
  u_int8_t* hmac = gcry_md_read(ctx_, 0);
  u_int32_t length = (packet.getAuthTagLength() < MAX_LENGTH_) ? packet.getAuthTagLength() : MAX_LENGTH_;
  std::memcpy(&tag[packet.getAuthTagLength() - length], &hmac[MAX_LENGTH_ - length], length);
}

bool Sha1AuthAlgo::checkTag(EncryptedPacket& packet)
{
  if(!packet.getAuthTagLength())
    return true;

  gcry_md_reset( ctx_ );

  gcry_md_write( ctx_, packet.getAuthenticatedPortion(), packet.getAuthenticatedPortionLength() );
  gcry_md_final( ctx_ );

  u_int8_t* tag = packet.getAuthTag();
  if(packet.getAuthTagLength() > MAX_LENGTH_)
    for(u_int32_t i=0; i < (packet.getAuthTagLength() - MAX_LENGTH_); ++i)
      if(tag[i]) return false; 
  
  u_int8_t* hmac = gcry_md_read(ctx_, 0);
  u_int32_t length = (packet.getAuthTagLength() < MAX_LENGTH_) ? packet.getAuthTagLength() : MAX_LENGTH_;
  if(std::memcmp(&tag[packet.getAuthTagLength() - length], &hmac[MAX_LENGTH_ - length], length))
    return false;

  return true;
}

u_int32_t Sha1AuthAlgo::getMaxLength()
{
  return MAX_LENGTH_;
}