├── .gitignore
├── LICENSE.md
├── README.md
├── client.js
├── cryptochat.js
├── encryption.js
├── package.json
└── server.js


/.gitignore:
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1 | node_modules
2 | 


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/LICENSE.md:
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 1 | #The MIT License (MIT)
 2 | 
 3 | *Copyright (c) 2015 Mateo Gianolio*
 4 | 
 5 | Permission is hereby granted, free of charge, to any person obtaining a copy
 6 | of this software and associated documentation files (the "Software"), to deal
 7 | in the Software without restriction, including without limitation the rights
 8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 9 | copies of the Software, and to permit persons to whom the Software is
10 | furnished to do so, subject to the following conditions:
11 | 
12 | The above copyright notice and this permission notice shall be included in all
13 | copies or substantial portions of the Software.
14 | 
15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 | SOFTWARE.
22 | 


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/README.md:
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  1 | # cryptochat
  2 | 
  3 | [![npm](https://img.shields.io/npm/dm/cryptochat.svg?style=flat-square)]()
  4 | 
  5 | [Encrypted](https://github.com/mateogianolio/cryptochat/blob/master/encryption.js) P2P chat over ICMP ([**I**nternet **C**ontrol **M**essage **P**rotocol](https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol)).
  6 | 
  7 | I strongly advise you to pick a high-entropy encryption key to avoid the possibility of brute-force attacks.
  8 | 
  9 | Uses [raw-socket](http://npmjs.org/package/raw-socket) for ICMP handling and [terminal-colors](https://github.com/tinganho/terminal-colors) to spice it up a bit.
 10 | 
 11 | ### Install and usage
 12 | 
 13 | Make sure you have node ```0.10.x``` (*tip:* use [n](https://www.npmjs.com/package/n)) and then install the package globally with ```sudo```.
 14 | 
 15 | ```bash
 16 | sudo npm install -g cryptochat
 17 | ```
 18 | 
 19 | Three variants of cryptochat are available depending on your use case:
 20 | 
 21 | * **Send** and **receive** messages
 22 |   ```bash
 23 |   $ sudo cryptochat <ip> <encryption_key>
 24 |   ```
 25 | 
 26 | * **Receive** messages
 27 |   ```bash
 28 |   $ sudo cryptochat server <encryption_key>
 29 |   ```
 30 | 
 31 | * **Send** messages
 32 |   ```bash
 33 |   $ sudo cryptochat client <ip> <encryption_key>
 34 |   ```
 35 | 
 36 | Because it relies on ```stdin``` for input, it is possible to use pipes to send data:
 37 | 
 38 | ```bash
 39 | cat cryptochat.js | sudo cryptochat client <ip> <encryption_key>
 40 | ```
 41 | 
 42 | ### [ICMP Echo request](https://en.wikipedia.org/wiki/Ping_(networking_utility)) format
 43 | 
 44 | <table>
 45 |   <tr>
 46 |     <td><b>bits 0-7</b></td>
 47 |     <td><b>bits 8-15</b></td>
 48 |     <td><b>bits 16-31</b></td>
 49 |   </tr>
 50 |   <tr>
 51 |     <td>type = <code>0x08</code></td>
 52 |     <td>code = <code>0x00</code></td>
 53 |     <td>checksum</td>
 54 |   </tr>
 55 |   <tr>
 56 |     <td colspan="2">identifier</td>
 57 |     <td>sequence number</td>
 58 |   </tr>
 59 |   <tr>
 60 |     <td colspan="3">payload</td>
 61 |   </tr>
 62 | </table>
 63 | 
 64 | The message data is attached as the ICMP payload.
 65 | 
 66 | ### Message
 67 | Messages are piped from ```stdin``` and split into payload packages, which are encrypted and sent as ICMP Echo requests. The payload size per request is currently set to 32 bytes. The first byte is the length of the message and the rest is the message itself.
 68 | 
 69 | The first request contains a salt and an initialization vector needed to decrypt the payloads.
 70 | 
 71 | <table>
 72 |   <tr>
 73 |     <td><b>byte 0</b></td>
 74 |     <td><b>bytes 1-15</b></td>
 75 |     <td><b>bytes 16-31</b></td>
 76 |   </tr>
 77 |   <tr>
 78 |     <td><code>0x3e</code></td>
 79 |     <td>salt</td>
 80 |     <td>initialization vector</td>
 81 |   </tr>
 82 | </table>
 83 | 
 84 | An "end" request is sent in order for the receiver to know when a message is completed. The end request has the following format:
 85 | 
 86 | <table>
 87 |   <tr>
 88 |     <td><b>byte 0</b></td>
 89 |     <td><b>bytes 1-31</b></td>
 90 |   </tr>
 91 |   <tr>
 92 |     <td><code>0x3e</code></td>
 93 |     <td><code>0xffffffff...</code></td>
 94 |   </tr>
 95 | </table>
 96 | 
 97 | When the end request is received, the full message is printed to the screen.
 98 | 
 99 | ### Contribute
100 | 
101 | As always, contributions are much appreciated.
102 | 


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/client.js:
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 1 | (function() {
 2 |   'use strict';
 3 |   module.exports = function(address, key) {
 4 |     if(!address) {
 5 |       console.log('Error: no IP address provided.');
 6 |       console.log('cryptochat <address> <encryption_key>');
 7 |       return;
 8 |     }
 9 | 
10 |     if(!key) {
11 |       console.log('Error: encryption key missing.');
12 |       console.log('cryptochat <address> <encryption_key>');
13 |       return;
14 |     }
15 | 
16 |     var raw = require('raw-socket'),
17 |         crypto = require('./encryption.js'),
18 |         socket = raw.createSocket({
19 |           protocol: raw.Protocol.ICMP
20 |         });
21 | 
22 |     process.stdin.setEncoding('utf8');
23 |     process.stdin.on('data', send);
24 | 
25 |     function send(msg) {
26 |       var payloads = msg.match(/.{1,31}/g),
27 |           packets = [],
28 |           payload,
29 |           length;
30 | 
31 |       var salt = crypto.salt(),
32 |           iv = crypto.iv(),
33 |           derivedKey = crypto.key(key, salt);
34 | 
35 |       packets.push(packet('3e' + salt.toString('hex') + iv.toString('hex')));
36 | 
37 |       for(var i = 0; i < payloads.length; i++) {
38 |         payload = payloads[i];
39 |         length = ('00' + (payload.length * 2).toString(16)).substr(-2);
40 |         payload = length + crypto.encrypt(payload, derivedKey, iv);
41 | 
42 |         packets.push(packet(payload));
43 |       }
44 | 
45 |       packets.push(packet('3e'));
46 | 
47 |       function ping() {
48 |         if(!packets.length)
49 |           return;
50 | 
51 |         var packet = packets.shift();
52 |         socket.send(packet, 0, packet.length, address, function(error) {
53 |           if(error)
54 |             throw error;
55 | 
56 |           ping();
57 |         });
58 |       }
59 | 
60 |       ping();
61 |     }
62 | 
63 |     function packet(message) {
64 |       while(message.length < 64)
65 |         message += 'f';
66 | 
67 |       var buffer = new Buffer(40);
68 |       buffer[0] = 0x08; // type
69 |       buffer[1] = 0x00; // code
70 |       buffer[2] = 0x00; // checksum placeholder
71 |       buffer[3] = 0x00; // checksum placeholder
72 |       buffer[4] = 0x00; // identifier
73 |       buffer[5] = 0x01; // identifier
74 |       buffer[6] = 0x0a; // seqnum
75 |       buffer[7] = 0x09; // seqnum
76 |       buffer.write(message, 8, 'hex');
77 |       raw.writeChecksum(buffer, 2, raw.createChecksum(buffer));
78 | 
79 |       return buffer;
80 |     }
81 |   };
82 | }());
83 | 


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/cryptochat.js:
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 1 | #!/usr/bin/env node
 2 | 
 3 | (function() {
 4 |   'use strict';
 5 | 
 6 |   var args = process.argv;
 7 | 
 8 |   args.shift(); // ignore 'node'
 9 |   args.shift(); // ignore path
10 | 
11 |   var ip,
12 |       key;
13 | 
14 |   var type = args.shift();
15 |   if(type === 'server') {
16 |     key = args.pop();
17 |     require('./server.js')(key);
18 |   } else if(type === 'client') {
19 |     key = args.pop();
20 |     ip = args.pop();
21 |     require('./client.js')(ip, key);
22 |   } else if(args.length === 1) {
23 |     ip = type;
24 |     key = args.pop();
25 |     require('./server.js')(key);
26 |     require('./client.js')(ip, key);
27 |   } else {
28 |     console.log('Error: invalid format.\n');
29 |     console.log('cryptochat <ip> <encryption_key>\t# send and receive messages');
30 |     console.log('cryptochat server <encryption_key>\t# receive messages');
31 |     console.log('cryptochat client <ip> <encryption_key>\t# send messages\n');
32 |     process.exit();
33 |   }
34 | }());
35 | 


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/encryption.js:
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 1 | (function() {
 2 |   'use strict';
 3 | 
 4 |   var ENCRYPTION = 'AES-256-CTR';
 5 |   var crypto = require('crypto');
 6 | 
 7 |   module.exports = {
 8 |     encrypt: function(str, key, iv) {
 9 |       var cipher = crypto.createCipheriv(ENCRYPTION, key, iv),
10 |           encrypted = cipher.update(str, 'utf8', 'hex');
11 |       encrypted += cipher.final('hex');
12 |       return encrypted;
13 |     },
14 |     decrypt: function(str, key, iv) {
15 |       var decipher = crypto.createDecipheriv(ENCRYPTION, key, iv),
16 |           decrypted = decipher.update(str, 'hex', 'utf8');
17 | 
18 |       decrypted += decipher.final('utf8');
19 |       return decrypted;
20 |     },
21 |     salt: function() {
22 |       return crypto.randomBytes(15);
23 |     },
24 |     iv: function() {
25 |       return crypto.randomBytes(16);
26 |     },
27 |     key: function(secret, salt) {
28 |       return crypto.pbkdf2Sync(secret, salt, 4096, 32);
29 |     },
30 |     hex2bytes: function(hex) {
31 |       if(hex.length % 2 !== 0)
32 |         throw new Error(hex + ' is not a valid hex string');
33 | 
34 |       var bytes = new Buffer(hex.length / 2);
35 |       for(var i = 0; i < hex.length; i += 2) {
36 |         bytes[i / 2] = parseInt(hex.substr(i, 2), 16);
37 |       }
38 | 
39 |       return bytes;
40 |     }
41 |   };
42 | }());
43 | 


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/package.json:
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 1 | {
 2 |   "name": "cryptochat",
 3 |   "version": "1.1.5",
 4 |   "description": "encrypted P2P chat over ICMP",
 5 |   "bin": {
 6 |     "cryptochat": "./cryptochat.js"
 7 |   },
 8 |   "dependencies": {
 9 |     "raw-socket": "^1.3.2",
10 |     "terminal-colors": "^0.1.3"
11 |   },
12 |   "devDependencies": {},
13 |   "scripts": {
14 |     "test": "echo \"Error: no test specified\" && exit 1"
15 |   },
16 |   "repository": {
17 |     "type": "git",
18 |     "url": "https://github.com/mateogianolio/cryptochat.git"
19 |   },
20 |   "keywords": [
21 |     "aes",
22 |     "aes-256",
23 |     "encrypted",
24 |     "encrypted chat",
25 |     "chat",
26 |     "chat application",
27 |     "chatting",
28 |     "crypto",
29 |     "cryptography",
30 |     "icmp",
31 |     "ping",
32 |     "internet control message protocol",
33 |     "ip",
34 |     "internet protocol"
35 |   ],
36 |   "author": "Mateo Gianolio",
37 |   "license": "MIT"
38 | }
39 | 


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/server.js:
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 1 | (function() {
 2 |   'use strict';
 3 |   module.exports = function(key) {
 4 |     require('terminal-colors');
 5 | 
 6 |     var DEBUG = false;
 7 |     var raw = require('raw-socket'),
 8 |         crypto = require('./encryption.js'),
 9 |         socket = raw.createSocket({
10 |           protocol: raw.Protocol.ICMP
11 |         });
12 | 
13 |     var message = '',
14 |         count = 0,
15 |         salt,
16 |         iv,
17 |         derivedKey,
18 |         offset,
19 |         type,
20 |         length,
21 |         hex;
22 | 
23 |     socket.on('message', listen);
24 |     function listen(buffer, source) {
25 |       // convert buffer to hex string, ignore IP header (20 bytes)
26 |       buffer = buffer.toString('hex', 20, buffer.length);
27 | 
28 |       /**
29 |        * types
30 |        * 0x00 = ICMP Echo reply,
31 |        * 0x08 = ICMP Echo request
32 |        **/
33 |       type = parseInt(buffer.substring(0, 2), 16);
34 |       length = parseInt(buffer.substring(16, 18), 16);
35 | 
36 |       // get message
37 |       offset = 18;
38 |       hex = buffer.substring(offset, offset + length);
39 | 
40 |       if(DEBUG) {
41 |         console.log('\nping #' + count);
42 |         console.log('buffer:', buffer);
43 |         console.log('type:', type === 0 ? 'ICMP Echo reply' : 'ICMP Echo request');
44 |         console.log('message length:', length);
45 |         console.log('message content:', hex);
46 |       }
47 | 
48 |       // ignore ICMP Echo replies
49 |       if(type === 0)
50 |         return;
51 | 
52 |       // encountered end ping
53 |       if((hex.match(/f/g) || []).length === length) {
54 |         if(message) {
55 |           process.stdout.write(source.green + ' ');
56 |           process.stdout.write('[' + (count + 1) + ']: ');
57 |           process.stdout.write(message.bold + '\n');
58 |         }
59 | 
60 |         count = 0;
61 |         message = '';
62 | 
63 |         return;
64 |       }
65 | 
66 |       // first ping
67 |       if(count === 0) {
68 |         salt = crypto.hex2bytes(hex.substring(0, 30));
69 |         iv = crypto.hex2bytes(hex.substring(30, 62));
70 |         derivedKey = crypto.key(key, salt);
71 | 
72 |         count++;
73 |         return;
74 |       }
75 | 
76 |       message += crypto.decrypt(hex, derivedKey, iv);
77 |       count++;
78 |     }
79 |   };
80 | }());
81 | 


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