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+# deHTTPS-Proxy - Access HTTPS Websites from Retro Computers
+
+## Purpose
+
+Today's web is based around Transport Layer Security (TLS) protocols, namely
+HTTPS.  In the last couple of years many sites that were previously available
+in plaintext have been made HTTPS-only.  This renders them inaccessable to
+retro computers such as the Apple II, which are not capabable of handling the
+cryptography.
+
+I had the idea of building an HTTP to HTTPS gateway, which allows requests to
+be submitted in plaintext HTTP and forwards them in HTTPS, acting as a kind
+of proxy.
+
+This particular implementation `dehttps-proxy.py` is a quick and dirty hack
+using Python 3.  The error handling is rather rough-and-ready but it does
+work fairly well in practice.
+
+## Configuration
+
+Edit `dehttps-proxy.py` and set the `PORT` to the desired value.  This will
+usually be port 80, the normal HTTP port.  You may also want to add any
+top level domains you use to the list `tlds = [ ... ]`.  This currently just
+has the common ones (`.com`, `.net`, `.gov` etc.)
+
+If you are using port 80 you will have to run the scrip as root:
+
+```
+sudo ./dehttps-proxy.py
+```
+
+## Using the Proxy
+
+I used the Contiki `WEBBROWS.SYSTEM` program on the Apple II for testing,
+but you can also use a modern browser such as Chromium or Firefox.
+
+Suppose you want to browse `https://www.example.com/path/to/page`.  Enter
+the following as the URL in your browser:
+`http://pi/www.example.com/path/to/page`, where `pi` is the hostname of
+your Raspberry Pi (or whatever system you are using to host the proxy.)
+
+Your request will go to port 80 (HTTP) on the server `pi` where it will be
+handled by `dehttps-proxy.py`.  The Python script adds `https:/` to the path
+that was passed in (`www.example.com/path/to/page` in this instance) and
+performs the HTTPS request.  The data that is obtained is returned to the
+original HTTP requester in plaintext.
+
+## Trick to Make Links Work (within a site)
+
+Many links on webpages are internal to the site. These links are specified
+using a relative rather than a fully qualified URL.  `dehttps-proxy.py` uses
+a trick to make these internal links work.  When a fully qualified URL like
+`www.example.com/path/to/page` is requested, the code keeps track of the
+website domain `www.example.com`.  The `https://www.example.com/` prefix is
+added to Subsequent relative links with URLs such as `path/to/another_page`.
+
+This trick does not work for links to other websites.  If you click on a
+link `https:://foo.com` then you will have to edit it to read
+`http://pi/foo.com` and resubmit it in the browser.
+