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|
<HTML
><HEAD
><TITLE
>HOWTO: Programming HTTPS in Python with M2Crypto</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.64
"></HEAD
><BODY
CLASS="ARTICLE"
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><DIV
CLASS="ARTICLE"
><DIV
CLASS="TITLEPAGE"
><H1
CLASS="TITLE"
><A
NAME="AEN2"
>HOWTO: Programming HTTPS in Python with M2Crypto</A
></H1
><H3
CLASS="AUTHOR"
><A
NAME="AEN4"
>Pheng Siong Ng</A
></H3
><DIV
CLASS="AFFILIATION"
><DIV
CLASS="ADDRESS"
><P
CLASS="ADDRESS"
>ngps@netmemetic.com</P
></DIV
></DIV
><P
CLASS="COPYRIGHT"
>Copyright © 2001, 2002 by Ng Pheng Siong.</P
><DIV
CLASS="REVHISTORY"
><TABLE
WIDTH="100%"
BORDER="0"
><TR
><TH
ALIGN="LEFT"
VALIGN="TOP"
COLSPAN="3"
><B
>Revision History</B
></TH
></TR
><TR
><TD
ALIGN="LEFT"
>Revision $Revision: 1.1 $</TD
><TD
ALIGN="LEFT"
>$Date: 2003/06/22 16:41:18 $</TD
><TD
ALIGN="LEFT"
></TD
></TR
><TR
><TD
ALIGN="LEFT"
COLSPAN="3"
></TD
></TR
></TABLE
></DIV
><HR></DIV
><DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="INTRODUCTION"
>Introduction</A
></H1
><P
><A
HREF="http://www.post1.com/home/ngps/m2"
TARGET="_top"
>M2Crypto</A
>
is a <A
HREF="http://www.python.org"
TARGET="_top"
>Python</A
>
interface to <A
HREF="http://www.openssl.org"
TARGET="_top"
>OpenSSL</A
>. It makes
available to the Python programmer SSL functionality to implement clients
and servers, S/MIME v2, RSA, DSA, DH, symmetric ciphers, message digests and
HMACs.
</P
><P
>This document demonstrates programming HTTPS with M2Crypto.
</P
></DIV
><DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="HTTPS"
>Programming HTTPS</A
></H1
>
<P>HTTPS - HTTP over SSL/TLS</P>
<P>Python has had good HTTP support for several years now. M2Crypto's
HTTPS functionality mostly adopts the interfaces in Python's HTTP modules.
</P>
<P>In this HOWTO, we shall begin with writing HTTPS clients. Now, to
test the HTTPS clients we write, we need a HTTPS server; conversely, to
test our HTTPS servers, we need a HTTPS client. ;-) </P>
<P> All the programs we write in this HOWTO are found in
<m2crypto>/demo/https.howto/. Additionally, a number of programs from
<m2crypto>/demo/ssl are also copied into this directory; their names are
prefixed by "orig". These "orig" programs shall be our known-working HTTPS
clients and servers. </P>
</DIV
>
<DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="SSLDUMP"
>ssldump</A
></H1
>
<P>ssldump "is an SSLv3/TLS network protocol analyser. It identifies
TCP connections on the chosen network interface and attempts to interpret
them as SSLv3/TLS traffic. When it identifies SSLv3/TLS traffic, it
decodes the records and displays them in a textual form to stdout. If
provided with the appropriate keying material, it will also decrypt the
connections and display the application data traffic.
</P>
<P>
If linked with OpenSSL, ssldump can display certificates in decoded form
and decrypt traffic (provided that it has the appropriate keying
material)."
</P>
<P>ssldump is written by Eric Rescorla.
</P>
</DIV
>
<DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="orig-https-srv.py"
>orig-https-srv.py</A
></H1
>
<P>orig_https_srv.py is an enhanced version of SimpleHTTPServer that
features the following:
</P>
<ul>
<li>Works over HTTPS.
<li>Uses one thread per connection.
<li>Generates directory listings.
<li>Displays SSL handshaking and SSL session info.
<li>Performs SSL renegotiation when a magic URL is requested.
</ul>
<p>Invoke orig_https_srv.py thusly:</p>
<pre>
$ python orig_https_srv.py
</pre>
<p>By default, orig_https_srv.py serves HTTPS on port 9443.</p>
</DIV
>
<DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="history"
>A bit of history</A
></H1
>
<p> M2Crypto was created during the time of Python 1.5, which features
a module httplib providing client-side HTTP functionality. M2Crypto sports
a httpslib based on httplib.
</p>
<p>
Beginning with version 2.0, Python's socket module provided
(rudimentary) SSL support. Also in the same version, httplib was
enhanced with class HTTPConnection, which is more sophisticated than
the old class HTTP, and HTTPSConnection, which does HTTPS.
</p>
<p>
Subsequently, M2Crypto.httpslib grew a compatible (but not identical)
class HTTPSConnection.
</p>
<p>
The primary interface difference between the two HTTPSConnection
classes is that M2Crypto's version accepts an M2Crypto.SSL.Context
instance as a parameter, whereas Python 2.x's SSL support does not
permit Pythonic control of the SSL context.
</p>
<p> Within the implementations, Python's
<tt>HTTPSConnection</tt> employs a
<tt>FakeSocket</tt> object, which collects all input from
the SSL connection before returning it to the application as a
<tt>StringIO</tt> buffer, whereas M2Crypto's
<tt>HTTPSConnection</tt> uses a buffering
<tt>M2Crypto.BIO.IOBuffer</tt> object that works over the
underlying M2Crypto.SSL.Connection directly. </p>
</DIV
>
<DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="simple-post"
>A simple HTTPS-POST client</A
></H1
>
</DIV
>
<DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="threaded-cli"
>A multi-threaded HTTPS client</A
></H1
>
</DIV
>
<DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="async-reuse-cli"
>An asynchronous session-reusing client</A
></H1
>
</DIV
>
<DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="verify-server-cert"
>Verifying server certificate</A
></H1
>
</DIV
>
<DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="using-client-cert"
>Using client certificate</A
></H1
>
</DIV
>
<DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="simple-https-server"
>SimpleHTTPSServer</A
></H1
>
</DIV
>
<DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="medusa-https-server"
>A Medusa-based HTTPS server</A
></H1
>
</DIV
>
<DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="verify-client-cert"
>Client certificate-based authentication</A
></H1
>
</DIV
>
<DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="control-session-reuse"
>Controlling session reuse</A
></H1
>
</DIV
>
</BODY
></HTML
>
|
