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libtins/include/crypto.h
2013-04-23 20:33:00 -03:00

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8.3 KiB
C++

/*
* Copyright (c) 2012, Matias Fontanini
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#ifndef TINS_CRYPTO_H
#define TINS_CRYPTO_H
#include <map>
#include <string>
#include <algorithm>
#include <vector>
#include "dot11.h"
#include "utils.h"
#include "snap.h"
#include "rawpdu.h"
namespace Tins {
class PDU;
namespace Crypto {
/**
* \brief RC4 Key abstraction.
*/
struct RC4Key {
static const size_t data_size = 256;
/**
* \brief Initializes the key using the provided iterator range.
*
* \param start The start of the range.
* \param end The end of the range.
*/
template<typename ForwardIterator>
RC4Key(ForwardIterator start, ForwardIterator end);
/**
* The actual key data.
*/
uint8_t data[data_size];
};
/**
*
*/
class WEPDecrypter {
public:
typedef Dot11::address_type address_type;
/**
* \brief Constructs a WEPDecrypter object.
*/
WEPDecrypter();
/**
* \brief Adds a decryption password.
*
* \param addr The access point's BSSID.
* \param password The password which will be used to decrypt
* packets sent from and to the AP identifier by the BSSID addr.
*/
void add_password(const address_type &addr, const std::string &password);
/**
* \brief Removes a decryption password
*
* \param addr The BSSID of the access point.
*/
void remove_password(const address_type &addr);
/**
* \brief Decrypts the provided PDU and forwards the decrypted
* PDU to the functor held by this object.
*
* A Dot11Data PDU is looked up inside the provided PDU chain.
* If no such PDU exists or there is no password associated
* with the Dot11 packet's BSSID, then the PDU is left intact.
*
* Otherwise, the packet is decrypted using the given password.
* If the CRC found after decrypting it is invalid,
* then false is returned.
*
* \return false if decryption failed due to invalid CRC, true
* otherwise.
*/
bool decrypt(PDU &pdu);
private:
typedef std::map<address_type, std::string> passwords_type;
PDU *decrypt(RawPDU &raw, const std::string &password);
passwords_type passwords;
std::vector<uint8_t> key_buffer;
};
/**
* \brief Pluggable decrypter object which can be used to decrypt
* data on sniffing sessions.
*
* This class holds a decrypter object and a functor, and implements
* a suitable operator() to be used on BaseSniffer::sniff_loop, which
* decrypts packets and forwards them to the given functor.
*/
template<typename Functor, typename Decrypter>
class DecrypterProxy {
public:
/**
* The type of the functor object.
*/
typedef Functor functor_type;
/**
* The type of the decrypter object.
*/
typedef Decrypter decrypter_type;
/**
* \brief Constructs an object from a functor and a decrypter.
* \param func The functor to be used to forward decrypted
* packets.
* \param decrypter The decrypter which will be used to decrypt
* packets
*/
DecrypterProxy(const functor_type &func,
const decrypter_type &decr = decrypter_type());
/**
* \brief Retrieves a reference to the decrypter object.
*/
decrypter_type &decrypter();
/**
* \brief Retrieves a const reference to the decrypter object.
*/
const decrypter_type &decrypter() const;
/**
* \brief The operator() which decrypts packets and forwards
* them to the functor.
*/
bool operator() (PDU &pdu);
private:
Functor functor_;
decrypter_type decrypter_;
};
/**
* \brief Performs RC4 encription/decryption of the given byte range,
* using the provided key.
*
* The decrypted range will be copied to the OutputIterator provided.
*
* \param start The beginning of the range.
* \param start The end of the range.
* \param key The key to be used.
* \param output The iterator in which to write the output.
*/
template<typename ForwardIterator, typename OutputIterator>
void rc4(ForwardIterator start, ForwardIterator end, RC4Key &key, OutputIterator output);
/**
* \brief Wrapper function to create DecrypterProxyes using a
* WEPDecrypter as the Decrypter template parameter.
*
* \param functor The functor to be forwarded to the DecrypterProxy
* constructor.
*/
template<typename Functor>
DecrypterProxy<Functor, WEPDecrypter> make_wep_decrypter_proxy(const Functor &functor);
// Implementation section
// DecrypterProxy
template<typename Functor, typename Decrypter>
DecrypterProxy<Functor, Decrypter>::DecrypterProxy(
const functor_type &func, const decrypter_type& decr)
: functor_(func), decrypter_(decr)
{
}
template<typename Functor, typename Decrypter>
typename DecrypterProxy<Functor, Decrypter>::decrypter_type &
DecrypterProxy<Functor, Decrypter>::decrypter()
{
return decrypter_;
}
template<typename Functor, typename Decrypter>
const typename DecrypterProxy<Functor, Decrypter>::decrypter_type &
DecrypterProxy<Functor, Decrypter>::decrypter() const
{
return decrypter_;
}
template<typename Functor, typename Decrypter>
bool DecrypterProxy<Functor, Decrypter>::operator() (PDU &pdu)
{
return decrypter_.decrypt(pdu) ? functor_(pdu) : true;
}
template<typename Functor>
DecrypterProxy<Functor, WEPDecrypter> make_wep_decrypter_proxy(const Functor &functor)
{
return DecrypterProxy<Functor, WEPDecrypter>(functor);
}
// RC4 stuff
template<typename ForwardIterator>
RC4Key::RC4Key(ForwardIterator start, ForwardIterator end) {
for(size_t i = 0; i < data_size; ++i)
data[i] = i;
size_t j = 0;
ForwardIterator iter = start;
for(size_t i = 0; i < data_size; ++i) {
j = (j + data[i] + *iter++) % 256;
if(iter == end)
iter = start;
std::swap(data[i], data[j]);
}
}
template<typename ForwardIterator, typename OutputIterator>
void rc4(ForwardIterator start, ForwardIterator end, RC4Key &key, OutputIterator output) {
size_t i = 0, j = 0;
while(start != end) {
i = (i + 1) % RC4Key::data_size;
j = (j + key.data[i]) % RC4Key::data_size;
std::swap(key.data[i], key.data[j]);
*output++ = *start++ ^ key.data[(key.data[i] + key.data[j]) % RC4Key::data_size];
}
}
}
}
#endif // TINS_CRYPTO_H