ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 1 | /* -*- c++ -*- */ |
Martin Jesper Low Madsen | af76964 | 2015-04-28 22:33:43 +0200 | [diff] [blame] | 2 | /* |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 3 | * Copyright 2014 <+YOU OR YOUR COMPANY+>. |
Martin Jesper Low Madsen | af76964 | 2015-04-28 22:33:43 +0200 | [diff] [blame] | 4 | * |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 5 | * This is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License as published by |
| 7 | * the Free Software Foundation; either version 3, or (at your option) |
| 8 | * any later version. |
Martin Jesper Low Madsen | af76964 | 2015-04-28 22:33:43 +0200 | [diff] [blame] | 9 | * |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 10 | * This software is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU General Public License for more details. |
Martin Jesper Low Madsen | af76964 | 2015-04-28 22:33:43 +0200 | [diff] [blame] | 14 | * |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 15 | * You should have received a copy of the GNU General Public License |
| 16 | * along with this software; see the file COPYING. If not, write to |
| 17 | * the Free Software Foundation, Inc., 51 Franklin Street, |
| 18 | * Boston, MA 02110-1301, USA. |
| 19 | */ |
| 20 | |
| 21 | #ifdef HAVE_CONFIG_H |
| 22 | #include "config.h" |
| 23 | #endif |
| 24 | |
| 25 | #include <gnuradio/io_signature.h> |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 26 | #include <grgsm/gsmtap.h> |
ptrkrysik | 5817a79 | 2015-04-25 18:51:08 +0200 | [diff] [blame] | 27 | #include <grgsm/endian.h> |
Roman Khassraf | 4dec540 | 2015-07-17 18:32:22 +0200 | [diff] [blame] | 28 | #include <numeric> |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 29 | #include "decryption_impl.h" |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 30 | |
Roman Khassraf | c51f12b | 2015-07-17 15:18:10 +0200 | [diff] [blame] | 31 | extern "C" { |
| 32 | #include <osmocom/gsm/a5.h> |
| 33 | } |
ptrkrysik | 5817a79 | 2015-04-25 18:51:08 +0200 | [diff] [blame] | 34 | |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 35 | const uint32_t BURST_SIZE=148; |
| 36 | |
| 37 | namespace gr { |
| 38 | namespace gsm { |
| 39 | |
| 40 | decryption::sptr |
Roman Khassraf | 4dec540 | 2015-07-17 18:32:22 +0200 | [diff] [blame] | 41 | decryption::make(const std::vector<uint8_t> & k_c, unsigned int a5_version) |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 42 | { |
| 43 | return gnuradio::get_initial_sptr |
Roman Khassraf | 4dec540 | 2015-07-17 18:32:22 +0200 | [diff] [blame] | 44 | (new decryption_impl(k_c, a5_version)); |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 45 | } |
| 46 | |
| 47 | /* |
| 48 | * The private constructor |
| 49 | */ |
Roman Khassraf | 4dec540 | 2015-07-17 18:32:22 +0200 | [diff] [blame] | 50 | decryption_impl::decryption_impl(const std::vector<uint8_t> & k_c, unsigned int a5_version) |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 51 | : gr::block("decryption", |
| 52 | gr::io_signature::make(0, 0, 0), |
Roman Khassraf | 4dec540 | 2015-07-17 18:32:22 +0200 | [diff] [blame] | 53 | gr::io_signature::make(0, 0, 0)), |
| 54 | d_k_c_valid(false) |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 55 | { |
| 56 | set_k_c(k_c); |
Roman Khassraf | 4dec540 | 2015-07-17 18:32:22 +0200 | [diff] [blame] | 57 | set_a5_version(a5_version); |
| 58 | validate_k_c(); |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 59 | |
| 60 | // std::cout << "Be careful with decryption block - it wasn't tested yet!" << std::endl; |
| 61 | message_port_register_in(pmt::mp("bursts")); |
| 62 | set_msg_handler(pmt::mp("bursts"), boost::bind(&decryption_impl::decrypt, this, _1)); |
| 63 | message_port_register_out(pmt::mp("bursts")); |
| 64 | } |
| 65 | |
| 66 | /* |
| 67 | * Virtual destructor |
| 68 | */ |
| 69 | decryption_impl::~decryption_impl() |
| 70 | { |
| 71 | } |
Martin Jesper Low Madsen | af76964 | 2015-04-28 22:33:43 +0200 | [diff] [blame] | 72 | |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 73 | void decryption_impl::set_k_c(const std::vector<uint8_t> & k_c) |
| 74 | { |
Roman Khassraf | 4dec540 | 2015-07-17 18:32:22 +0200 | [diff] [blame] | 75 | d_k_c = k_c; |
| 76 | } |
| 77 | |
| 78 | void decryption_impl::set_a5_version(unsigned int a5_version) |
| 79 | { |
| 80 | d_a5_version = 1; |
| 81 | if (a5_version >= 1 && a5_version <= 4) |
Roman Khassraf | c51f12b | 2015-07-17 15:18:10 +0200 | [diff] [blame] | 82 | { |
Roman Khassraf | 4dec540 | 2015-07-17 18:32:22 +0200 | [diff] [blame] | 83 | d_a5_version = a5_version; |
| 84 | } |
| 85 | } |
| 86 | |
| 87 | void decryption_impl::validate_k_c() |
| 88 | { |
| 89 | if (d_k_c.size() == 0) |
| 90 | { |
| 91 | d_k_c_valid = false; |
| 92 | return; |
| 93 | } |
| 94 | else if ((d_a5_version < 4 && d_k_c.size() != 8) || (d_a5_version == 4 && d_k_c.size() != 16)) |
| 95 | { |
| 96 | d_k_c_valid = false; |
| 97 | return; |
Roman Khassraf | c51f12b | 2015-07-17 15:18:10 +0200 | [diff] [blame] | 98 | } |
| 99 | else |
| 100 | { |
Roman Khassraf | 4dec540 | 2015-07-17 18:32:22 +0200 | [diff] [blame] | 101 | for (int i=0; i<d_k_c.size(); i++) |
Roman Khassraf | c51f12b | 2015-07-17 15:18:10 +0200 | [diff] [blame] | 102 | { |
Roman Khassraf | 4dec540 | 2015-07-17 18:32:22 +0200 | [diff] [blame] | 103 | if (d_k_c[i] != 0) |
| 104 | { |
| 105 | d_k_c_valid = true; |
| 106 | return; |
| 107 | } |
Roman Khassraf | c51f12b | 2015-07-17 15:18:10 +0200 | [diff] [blame] | 108 | } |
| 109 | } |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 110 | } |
Martin Jesper Low Madsen | af76964 | 2015-04-28 22:33:43 +0200 | [diff] [blame] | 111 | |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 112 | void decryption_impl::decrypt(pmt::pmt_t msg) |
| 113 | { |
Roman Khassraf | 4dec540 | 2015-07-17 18:32:22 +0200 | [diff] [blame] | 114 | if (!d_k_c_valid) |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 115 | { |
| 116 | message_port_pub(pmt::mp("bursts"), msg); |
Roman Khassraf | 4dec540 | 2015-07-17 18:32:22 +0200 | [diff] [blame] | 117 | } |
| 118 | else |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 119 | { |
| 120 | uint8_t decrypted_data[BURST_SIZE]; |
Roman Khassraf | c51f12b | 2015-07-17 15:18:10 +0200 | [diff] [blame] | 121 | uint8_t keystream[114]; |
Martin Jesper Low Madsen | af76964 | 2015-04-28 22:33:43 +0200 | [diff] [blame] | 122 | |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 123 | pmt::pmt_t header_plus_burst = pmt::cdr(msg); |
| 124 | gsmtap_hdr * header = (gsmtap_hdr *)pmt::blob_data(header_plus_burst); |
| 125 | uint8_t * burst_binary = (uint8_t *)(pmt::blob_data(header_plus_burst))+sizeof(gsmtap_hdr); |
Martin Jesper Low Madsen | af76964 | 2015-04-28 22:33:43 +0200 | [diff] [blame] | 126 | |
ptrkrysik | 4739c94 | 2015-02-07 19:51:03 +0100 | [diff] [blame] | 127 | uint32_t frame_number = be32toh(header->frame_number); |
| 128 | bool uplink_burst = (be16toh(header->arfcn) & 0x4000) ? true : false; |
Martin Jesper Low Madsen | af76964 | 2015-04-28 22:33:43 +0200 | [diff] [blame] | 129 | |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 130 | if(uplink_burst){ |
| 131 | //process uplink burst |
Roman Khassraf | 4dec540 | 2015-07-17 18:32:22 +0200 | [diff] [blame] | 132 | osmo_a5(d_a5_version, &d_k_c[0], frame_number, NULL, keystream); |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 133 | } else { |
| 134 | //process downlink burst |
Roman Khassraf | 4dec540 | 2015-07-17 18:32:22 +0200 | [diff] [blame] | 135 | osmo_a5(d_a5_version, &d_k_c[0], frame_number, keystream, NULL); |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 136 | } |
| 137 | /* guard bits */ |
| 138 | for (int i = 0; i < 3; i++) { |
| 139 | decrypted_data[i] = burst_binary[i]; |
| 140 | } |
ptrkrysik | a1871f5 | 2014-12-15 09:38:00 +0100 | [diff] [blame] | 141 | //encrypt first part of the burst |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 142 | for (int i = 0; i < 57; i++) { |
| 143 | decrypted_data[i+3] = keystream[i] ^ burst_binary[i+3]; |
| 144 | } |
| 145 | /* stealing bits and midamble */ |
| 146 | for (int i = 60; i < 88; i++) { |
| 147 | decrypted_data[i] = burst_binary[i]; |
| 148 | } |
ptrkrysik | a1871f5 | 2014-12-15 09:38:00 +0100 | [diff] [blame] | 149 | //encrypt second part of the burst |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 150 | for (int i = 0; i < 57; i++) { |
| 151 | decrypted_data[i+88] = keystream[i+57] ^ burst_binary[i+88]; |
| 152 | } |
| 153 | /* guard bits */ |
| 154 | for (int i = 145; i < 148; i++) { |
| 155 | decrypted_data[i] = burst_binary[i]; |
| 156 | } |
| 157 | uint8_t new_header_plus_burst[sizeof(gsmtap_hdr)+BURST_SIZE]; |
| 158 | memcpy(new_header_plus_burst, header, sizeof(gsmtap_hdr)); |
| 159 | memcpy(new_header_plus_burst+sizeof(gsmtap_hdr), decrypted_data, BURST_SIZE); |
Martin Jesper Low Madsen | af76964 | 2015-04-28 22:33:43 +0200 | [diff] [blame] | 160 | |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 161 | pmt::pmt_t msg_binary_blob = pmt::make_blob(new_header_plus_burst, sizeof(gsmtap_hdr)+BURST_SIZE); |
| 162 | pmt::pmt_t msg_out = pmt::cons(pmt::PMT_NIL, msg_binary_blob); |
Martin Jesper Low Madsen | af76964 | 2015-04-28 22:33:43 +0200 | [diff] [blame] | 163 | |
ptrkrysik | 18b631e | 2014-12-15 09:09:18 +0100 | [diff] [blame] | 164 | message_port_pub(pmt::mp("bursts"), msg_out); |
| 165 | } |
| 166 | return; |
| 167 | } |
| 168 | } /* namespace gsm */ |
| 169 | } /* namespace gr */ |