mtu | e398df0 | 2017-08-22 11:37:07 +0200 | [diff] [blame] | 1 | { |
| 2 | "cells": [ |
| 3 | { |
| 4 | "cell_type": "markdown", |
| 5 | "metadata": {}, |
| 6 | "source": [ |
| 7 | "# TLS handshake overview\n", |
| 8 | "This is the standard, modern TLS 1.2 handshake:\n", |
| 9 | "\n", |
| 10 | "<img src=\"images/handshake_tls12.png\" alt=\"Handshake TLS 1.2\" width=\"400\"/>" |
| 11 | ] |
| 12 | }, |
| 13 | { |
| 14 | "cell_type": "code", |
| 15 | "execution_count": null, |
| 16 | "metadata": { |
| 17 | "collapsed": true |
| 18 | }, |
| 19 | "outputs": [], |
| 20 | "source": [ |
| 21 | "# We're going to parse several successive records from the passive listening of a standard TLS handshake\n", |
| 22 | "from scapy.all import *" |
| 23 | ] |
| 24 | }, |
| 25 | { |
| 26 | "cell_type": "markdown", |
| 27 | "metadata": {}, |
| 28 | "source": [ |
| 29 | "## (C) ---> (S) ClientHello" |
| 30 | ] |
| 31 | }, |
| 32 | { |
| 33 | "cell_type": "code", |
| 34 | "execution_count": null, |
| 35 | "metadata": { |
| 36 | "collapsed": false |
| 37 | }, |
| 38 | "outputs": [], |
| 39 | "source": [ |
| 40 | "record1 = TLS(open('raw_data/tls_session_protected/01_cli.raw').read())\n", |
| 41 | "record1.show()" |
| 42 | ] |
| 43 | }, |
| 44 | { |
| 45 | "cell_type": "code", |
| 46 | "execution_count": null, |
| 47 | "metadata": { |
| 48 | "collapsed": false |
| 49 | }, |
| 50 | "outputs": [], |
| 51 | "source": [ |
| 52 | "for extension in record1.msg[0].ext:\n", |
| 53 | " print ''\n", |
| 54 | " extension.show()" |
| 55 | ] |
| 56 | }, |
| 57 | { |
| 58 | "cell_type": "markdown", |
| 59 | "metadata": {}, |
| 60 | "source": [ |
| 61 | "## (C) <--- (S) ServerHello" |
| 62 | ] |
| 63 | }, |
| 64 | { |
| 65 | "cell_type": "code", |
| 66 | "execution_count": null, |
| 67 | "metadata": { |
| 68 | "collapsed": false |
| 69 | }, |
| 70 | "outputs": [], |
| 71 | "source": [ |
| 72 | "record2 = TLS(open('raw_data/tls_session_protected/02_srv.raw').read())\n", |
| 73 | "record2.show()" |
| 74 | ] |
| 75 | }, |
| 76 | { |
| 77 | "cell_type": "markdown", |
| 78 | "metadata": {}, |
| 79 | "source": [ |
| 80 | "## (C) <--- (S) Certificate" |
| 81 | ] |
| 82 | }, |
| 83 | { |
| 84 | "cell_type": "code", |
| 85 | "execution_count": null, |
| 86 | "metadata": { |
| 87 | "collapsed": false |
| 88 | }, |
| 89 | "outputs": [], |
| 90 | "source": [ |
| 91 | "record3 = TLS(open('raw_data/tls_session_protected/03_srv.raw').read())\n", |
| 92 | "record3.show()" |
| 93 | ] |
| 94 | }, |
| 95 | { |
| 96 | "cell_type": "code", |
| 97 | "execution_count": null, |
| 98 | "metadata": { |
| 99 | "collapsed": false |
| 100 | }, |
| 101 | "outputs": [], |
| 102 | "source": [ |
| 103 | "# The Certificate message actually contains a *chain* of certificates\n", |
| 104 | "for cert in record3.msg[0].certs:\n", |
| 105 | " print type(cert[1])\n", |
| 106 | " cert[1].show()\n", |
| 107 | " print ''" |
| 108 | ] |
| 109 | }, |
| 110 | { |
| 111 | "cell_type": "code", |
| 112 | "execution_count": null, |
| 113 | "metadata": { |
| 114 | "collapsed": false |
| 115 | }, |
| 116 | "outputs": [], |
| 117 | "source": [ |
| 118 | "# Let's recall the domain that the client wants to access\n", |
| 119 | "record1.msg[0].ext[0].show()\n", |
| 120 | "\n", |
| 121 | "# Indeed the certificate may be used with other domains than its CN 'www.github.com'\n", |
| 122 | "x509c = record3.msg[0].certs[0][1].x509Cert\n", |
| 123 | "print type(x509c)\n", |
| 124 | "x509c.tbsCertificate.extensions[2].show()" |
| 125 | ] |
| 126 | }, |
| 127 | { |
| 128 | "cell_type": "markdown", |
| 129 | "metadata": {}, |
| 130 | "source": [ |
| 131 | "## (C) <--- (S) CertificateStatus, ServerKeyExchange, ServerHelloDone" |
| 132 | ] |
| 133 | }, |
| 134 | { |
| 135 | "cell_type": "code", |
| 136 | "execution_count": null, |
| 137 | "metadata": { |
| 138 | "collapsed": false |
| 139 | }, |
| 140 | "outputs": [], |
| 141 | "source": [ |
| 142 | "# Here the server sent three TLS records in the same TCP segment\n", |
| 143 | "record4 = TLS(open('raw_data/tls_session_protected/04_srv.raw').read())\n", |
| 144 | "record4.show()" |
| 145 | ] |
| 146 | }, |
| 147 | { |
| 148 | "cell_type": "code", |
| 149 | "execution_count": null, |
| 150 | "metadata": { |
| 151 | "collapsed": false |
| 152 | }, |
| 153 | "outputs": [], |
| 154 | "source": [ |
| 155 | "# Let's verify the signature in the ServerKeyExchange\n", |
| 156 | "# First, we need to assemble the whole data being signed\n", |
| 157 | "cli_random = pkcs_i2osp(record1.msg[0].gmt_unix_time, 4) + record1.msg[0].random_bytes\n", |
| 158 | "srv_random = pkcs_i2osp(record2.msg[0].gmt_unix_time, 4) + record2.msg[0].random_bytes\n", |
| 159 | "ecdh_params = str(record4[TLSServerKeyExchange].params)\n", |
| 160 | "\n", |
| 161 | "# Then we retrieve the server's Cert and verify the signature\n", |
| 162 | "cert_srv = record3.msg[0].certs[0][1]\n", |
| 163 | "cert_srv.verify(cli_random + srv_random + ecdh_params, record4[TLSServerKeyExchange].sig.sig_val, h='sha512')" |
| 164 | ] |
| 165 | }, |
| 166 | { |
| 167 | "cell_type": "markdown", |
| 168 | "metadata": { |
| 169 | "collapsed": true |
| 170 | }, |
| 171 | "source": [ |
| 172 | "## (C) ---> (S) ClientKeyExchange, ChangeCipherSpec, Finished" |
| 173 | ] |
| 174 | }, |
| 175 | { |
| 176 | "cell_type": "code", |
| 177 | "execution_count": null, |
| 178 | "metadata": { |
| 179 | "collapsed": false |
| 180 | }, |
| 181 | "outputs": [], |
| 182 | "source": [ |
| 183 | "record5_str = open('raw_data/tls_session_protected/05_cli.raw').read()\n", |
| 184 | "record5 = TLS(record5_str)\n", |
| 185 | "record5.show()" |
| 186 | ] |
| 187 | }, |
| 188 | { |
| 189 | "cell_type": "code", |
| 190 | "execution_count": null, |
| 191 | "metadata": { |
| 192 | "collapsed": false |
| 193 | }, |
| 194 | "outputs": [], |
| 195 | "source": [ |
| 196 | "# Every record has a 'tls_session' context which may enhance the parsing of later records\n", |
| 197 | "record5 = TLS(record5_str, tls_session=record2.tls_session.mirror())\n", |
| 198 | "record5.show()" |
| 199 | ] |
| 200 | }, |
| 201 | { |
| 202 | "cell_type": "markdown", |
| 203 | "metadata": {}, |
| 204 | "source": [ |
| 205 | "## (C) <--- (S) NewSessionTicket, ChangeCipherSpec, Finished" |
| 206 | ] |
| 207 | }, |
| 208 | { |
| 209 | "cell_type": "code", |
| 210 | "execution_count": null, |
| 211 | "metadata": { |
| 212 | "collapsed": false |
| 213 | }, |
| 214 | "outputs": [], |
| 215 | "source": [ |
| 216 | "record6_str = open('raw_data/tls_session_protected/06_srv.raw').read()\n", |
| 217 | "record6 = TLS(record6_str, tls_session=record5.tls_session.mirror())\n", |
| 218 | "record6.show()" |
| 219 | ] |
| 220 | }, |
| 221 | { |
| 222 | "cell_type": "markdown", |
| 223 | "metadata": {}, |
| 224 | "source": [ |
| 225 | "## (C) ---> (S) ApplicationData" |
| 226 | ] |
| 227 | }, |
| 228 | { |
| 229 | "cell_type": "code", |
| 230 | "execution_count": null, |
| 231 | "metadata": { |
| 232 | "collapsed": false |
| 233 | }, |
| 234 | "outputs": [], |
| 235 | "source": [ |
| 236 | "record7_str = open('raw_data/tls_session_protected/07_cli.raw').read()\n", |
| 237 | "record7 = TLS(record7_str, tls_session=record6.tls_session.mirror())\n", |
| 238 | "record7.show()" |
| 239 | ] |
| 240 | } |
| 241 | ], |
| 242 | "metadata": { |
| 243 | "kernelspec": { |
| 244 | "display_name": "Python 2", |
| 245 | "language": "python", |
| 246 | "name": "python2" |
| 247 | }, |
| 248 | "language_info": { |
| 249 | "codemirror_mode": { |
| 250 | "name": "ipython", |
| 251 | "version": 2 |
| 252 | }, |
| 253 | "file_extension": ".py", |
| 254 | "mimetype": "text/x-python", |
| 255 | "name": "python", |
| 256 | "nbconvert_exporter": "python", |
| 257 | "pygments_lexer": "ipython2", |
| 258 | "version": "2.7.13" |
| 259 | } |
| 260 | }, |
| 261 | "nbformat": 4, |
| 262 | "nbformat_minor": 2 |
| 263 | } |