notebooks/tls/notebook1_x509.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Notebook 1: X.509 certificates"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Jupyter notebook cheat sheet"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "# Use Shift+Enter to run the current cell\n",
    "print 'Hello!'"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "# You may also use Alt+Enter to run the current cell, then create a new cell right below\n",
    "from datetime import datetime\n",
    "print 'This is the time right now: %s' % datetime.now()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "# If needed, pause the cell edition with Ctrl-M.\n",
    "# Then you can delete the current cell with D+D. You can also undo cell deletion with Z.\n",
    "# Finally, should Jupyter become stuck in execution, use Kernel/Interrupt from the menu bar.\n",
    "print 'Got it!'"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Data manipulation with Scapy"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "from scapy.all import *\n",
    "load_layer('tls')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "keystr = open('raw_data/pki/ca_key.der', 'rb').read()\n",
    "print repr(keystr)\n",
    "# (btw, you can hide the output of a cell by double-clicking on the left of the output)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "privkey = RSAPrivateKey(keystr)\n",
    "privkey.show()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "v = privkey.version\n",
    "print 'The \\'version\\' stripped from any ASN.1 encoding is 0x%02x.' % v.val\n",
    "print 'The \\'version\\' field corresponds to bytes  %r.' % raw(v)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "privkey.version = ASN1_INTEGER(1)\n",
    "privkey.modulus.val *= 2\n",
    "privkey.show()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "print 'Original data: %r...' % keystr[:13]\n",
    "print 'New version bytes:          %r' % raw(privkey.version)\n",
    "print 'New modulus bytes:                      %r...' % raw(privkey.modulus)[:6]\n",
    "print 'Rebuilt data:  %r...' % raw(privkey)[:13]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "collapsed": true
   },
   "source": [
    "## X.509 certificate features"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "# Let's reload the original key, then let's load a certificate associated with it\n",
    "privkey = RSAPrivateKey(keystr)\n",
    "cert = X509_Cert(open('raw_data/pki/ca_cert.der', 'rb').read())\n",
    "cert.show()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "cert.tbsCertificate.subjectPublicKeyInfo.subjectPublicKey.show()\n",
    "cert.tbsCertificate.subject[-1].rdn[0].show()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "scrolled": true
   },
   "outputs": [],
   "source": [
    "cert.tbsCertificate.subjectPublicKeyInfo.subjectPublicKey.modulus == privkey.modulus"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "cert.tbsCertificate.extensions[2].show()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "cert.signatureAlgorithm.algorithm"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Scapy crypto tools"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "# Let's reload the key with Scapy's crypto-enhanced wrapper\n",
    "privkey = PrivKey('raw_data/pki/ca_key.der')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "privkey.der == keystr"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "print privkey.key\n",
    "print privkey.pubkey"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "# We can compute the RSA signature over the part of the certificate which is to be signed\n",
    "privkey.sign(raw(cert.tbsCertificate))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "cert.signatureValue"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "# We can quickly modify a certificate field and update the signature accordingly\n",
    "cert.tbsCertificate.serialNumber.val = 0xdeadcafe\n",
    "cert.tbsCertificate.subject[-1].rdn[0].value.val = 'my new deadcafe CA'    \n",
    "cert2 = privkey.resignCert(cert)\n",
    "cert2.show()"
   ]
  }
 ],
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