tidy up markdown (the result was producing invalid XML)

[raven/abandoned/asp.git] / README.md

University of Cambridge Classic ASP/VBScript Raven Authentication Module - v.1.0 (29/04/2014)\r
==========================================================================\r
\r
Description\r
-----------\r
This software comprises a VBScript class 'Ucam_Webauth' and sample\r
files that provide a Classic ASP/VBScript implementation of a 'Raven'\r
authentication module; Raven is the web authentication protocol used\r
by the University of Cambridge, UK. The logic and code of the\r
'Ucam_Webauth' class are loosely based on the PHP Raven authentication\r
class provided at http://raven.cam.ac.uk/project/.\r
- For a full description of the latest Raven specification and an explanation \r
of how Raven works, go to http://raven.cam.ac.uk/project/.\r
- This software was originally created for the Careers Service,\r
University of Cambridge by sh801@cam.ac.uk. For support, please\r
contact raven-support@ucs.cam.ac.uk\r
\r
Files and folders\r
-----------------\r
- [certificates]: Temporary location for Raven public key certificates.\r
- [js]: Folder containing Javascript cryptography libraries.\r
- [docs]: Supporting documentation.\r
- [logs]: Possible location for log files created by the module.\r
- Default.asp: A sample file showing how the 'Ucam_Webauth' class is used \r
to provide Raven authentication.\r
- Test.asp: A test file for unit testing the 'Ucam_Webauth' module using the \r
'Ucam_RavenWLS' dummy Raven server (separate project, not included).\r
- Ucam_Webauth.vbs: The main 'Ucam_Webauth' VBScript class.\r
\r
Platform requirements\r
---------------------\r
This module has been tested on IIS7 with .NET Framework set to \r
'No managed code', ie. classic ASP.\r
\r
Installation\r
------------\r
### Cryptographic functions\r
Cryptographic functions are provided by the Javascript libraries within the \r
'js' folder. These libraries are versions of the client-side Javascript \r
libraries provided at http://kjur.github.io/jsrsasign/index.html \r
but modified to run server-side. There is no need to install any \r
additional cryptography libraries.\r
\r
### Install Raven certificates\r
The authentication module uses the Raven public key certificate at \r
https://raven.cam.ac.uk/project/keys/ to verify authentication responses. \r
Download the certificate from https://raven.cam.ac.uk/project/keys/ and copy \r
to the 'certificates' folder provided with this authentication module \r
download - the 'certificates' folder is a temporary location for the \r
certificate while you get the module up and running. You will need to supply \r
the full path to the 'certificates' folder as either a 'key_dir' argument \r
to the 'Ucam_Webauth' constructor or by modifying the 'Ucam_Webauth' \r
variable 'DEFAULT_KEY_DIR' directly. \r
\r
Once you have everything working, move the 'certificates' folder \r
to a new location on your webserver that is not web- or publicly-accessible \r
and modify the 'key_dir' string accordingly.\r
 \r
- NOTE: you may have to change the name of the key file from 'pubkey2.crt' \r
to '2.crt'. \r
\r
If you're using the Raven test server \r
(http://raven.cam.ac.uk/project/test-demo/) for testing purposes, make sure \r
you install the test server keys instead, but ensure you remove these keys \r
before using the authentication module in a production environment, as \r
recommended by the demo Raven server:\r
\r
> It is vital to keep these demo keys seperate from keys \r
> used with a production service - failure to do so could \r
> allow an attacker to successfully replay a response \r
> from the demonstration server, which anyone can easily \r
> obtain, against a production service. \r
\r
Getting started\r
---------------\r
\r
The 'Ucam_Webauth' VBScript class must be used within an ASP server-side page \r
as it interacts directly with a user's browser session. To use the \r
'Ucam_Webauth' VBScript class:\r
\r
- 1. Ensure the 'Ucam_Webauth.vbs' class file and the folder 'js' are in the \r
same directory as your ASP script. The folders 'certificates' and 'logs' may \r
also be located here temporarily. \r
- 2. Include the 'Ucam_Webauth.vbs' class file in the 'head' of your ASP file:\r
\r
```\r
<head>\r
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">\r
<!--#include file="Ucam_Webauth.vbs"-->\r
</head>\r
\r
```\r
\r
- 3. Set up the initial arguments for the 'Ucam_Webauth' class:\r
\r
```\r
Set args = CreateObject("Scripting.Dictionary")\r
args.Add "hostname", "localhost"\r
args.Add "auth_service", "https://demo.raven.cam.ac.uk/auth/authenticate.html"\r
args.Add "key_dir", "C:/Ucam_Webauth/certificates"\r
```\r
\r
'args' is an associative array of *text* strings so parameter values must \r
be converted into strings, ie. numbers and booleans must be supplied within \r
quotes as in "23", "TRUE", "FALSE".\r
A full list of allowed parameters is provided at the end of this README. \r
\r
- 4. Create an instance of the 'Ucam_Webauth' class from within your ASP \r
server page and initialize with setup variables:\r
\r
```\r
Set oUcam_Webauth = New Ucam_Webauth\r
Call oUcam_Webauth(args)       \r
```\r
   \r
- 5. Call 'Authenticate()' on the Ucam_Webauth object and act according to \r
the value returned:\r
\r
```\r
	Select Case oUcam_Webauth.Authenticate()\r
		\r
		Case oUcam_Webauth.AUTHENTICATE_INCOMPLETE\r
\r
			...			\r
			Exit Sub\r
\r
		Case oUcam_Webauth.AUTHENTICATE_COMPLETE_AUTHENTICATED		\r
\r
			...\r
					\r
		Case oUcam_Webauth.AUTHENTICATE_COMPLETE_NOT_AUTHENTICATED		\r
\r
			...\r
\r
		Case oUcam_Webauth.AUTHENTICATE_COMPLETE_ERROR		\r
\r
			...\r
					\r
	End Select\r
```\r
\r
The four possible return values of 'Authenticate()' are:\r
\r
- AUTHENTICATE_INCOMPLETE : The authentication process has yet to complete. \r
The user may have been redirected to the Raven server and has yet to enter \r
their login details.\r
- AUTHENTICATE_COMPLETE_AUTHENTICATED : The authentication process completed \r
and the user has been successfully authenticated.\r
- AUTHENTICATE_COMPLETE_NOT_AUTHENTICATED : The authentication process \r
completed and the user was not successfully authenticated. \r
The user may have clicked 'Cancel' at the Raven server.\r
- AUTHENTICATE_COMPLETE_ERROR : There was an error during the authentication \r
process forcing the authentication cycle to terminate early.\r
\r
As the 'Authenticate()' function may need to send HTTP headers, it must be \r
called before any output (e.g. HTML, HTTP headers) is sent to the browser.\r
\r
The 'Default.asp' file provided is a sample of a simple server page using \r
the 'Ucam_Webauth' VBScript class.\r
\r
Overview of Raven process\r
-------------------------\r
A diagram of the Raven authentication process is located within the 'docs' \r
folder as [I - Overview of Raven Authentication Process.pdf]. \r
\r
The authentication cycle consists of the following key stages:\r
\r
#### User first tries to access authenticated page\r
User tries to load an authenticated page on a particular website. \r
The 'Ucam_Webauth' class is loaded and the 'Authenticate()' function is called. \r
If no authentication cookie is found to indicate the user is authenticated, \r
the user's browser is redirected to a separate Raven server using a special \r
'Authentication Request'. The authentication request consists of a series of \r
authentication parameters encoded into the URL redirect as name/value pairs.\r
\r
#### User is prompted for login information\r
The Raven server interprets the authentication request sent by the main \r
website and prompts the user for their username and password. The user may \r
then be successfully authenticated or may decide to click 'Cancel'. They are \r
redirected back to the main website with a series of 'Authentication Response' \r
parameters encoded into a 'WLS-Response' GET variable.\r
\r
#### User redirected back to main webserver\r
The user's original page is loaded again and 'Authenticate()' is called a \r
second time. 'Ucam_Webauth' processes the new 'WLS-Response' GET value and, \r
if it's valid, sets an authentication cookie on the user's browser. The \r
user's original page is then loaded again. \r
\r
#### User redirected back to main webserver again \r
With an authentication cookie now set, 'Authenticate()' checks the status \r
code contained in the value of the authentication cookie and returns either \r
'AUTHENTICATE_COMPLETE_AUTHENTICATED' or \r
'AUTHENTICATE_COMPLETE_NOT_AUTHENTICATED'. If \r
'AUTHENTICATE_COMPLETE_AUTHENTICATED' is returned , the original page can \r
go on to display authenticated content to the user.\r
\r
Specifics of module\r
-------------------\r
The 'Authenticate()' function is the overarching authentication function of \r
'Ucam_Webauth'. It performs some basic sanity checks using 'CheckSetup()' \r
then uses 'GetCurrentState()' to establish the current state of the \r
authentication process before branching accordingly. The possible return \r
values of 'GetCurrentState()' are:\r
\r
#### STATE_NEW_AUTHENTICATION\r
A completely fresh authentication. 'SendAuthenticationRequest()' [*1*] is \r
then triggered which performs some basic data checks, sets the authentication \r
cookie to 'AUTHENTICATIONCOOKIE_REDIRECT_WLS' (to record where we are in the \r
authentication process) and redirects the user's browser to the Raven \r
authentication server with a series of authentication parameters \r
encoded as name/value pairs.\r
\r
#### STATE_WLS_RESPONSE_RECEIVED\r
The Raven authentication server has processed the user and has returned the \r
user's browser back to the original website with a series of authentication \r
response parameters encoded into the 'WLS-Response' GET variable. \r
'ProcessAuthenticationResponse()' [*2*] is then called which checks the \r
validity of the 'WLS-Response' value, sets an authentication cookie and \r
redirects the user back to the original page.\r
\r
#### STATE_WAA_AUTHENTICATIONCOOKIE_SET\r
A valid authentication cookie has been set \r
(<> AUTHENTICATIONCOOKIE_REDIRECT_WLS). \r
'ProcessAuthenticationCookie()' [*3*] is then called which checks the \r
validity of the cookie. If the cookie has expired, \r
'SendAuthenticationRequest()' is called again in case the user needs to \r
reauthenticate themselves. If the cookie is still valid, an \r
'AUTHENTICATE_COMPLETE_XXX' value is returned, indicating that the \r
authentication cycle has completed successfully. \r
NOTE: this may be true if the user has cancelled the authentication process, \r
in which case 'AUTHENTICATE_COMPLETE_NOT_AUTHENTICATED' will be returned.\r
\r
#### STATE_ERROR\r
An error occurred, breaking the authentication cycle and returning \r
AUTHENTICATE_COMPLETE_ERROR to 'Authenticate()'. This return value will \r
also be generated by the other functions above if they generate an error.\r
\r
## Accompanying diagrams\r
Detailed diagrams of the Raven process flow for (i) a successful \r
authentication (ii) a cancelled authentication, are located in the 'docs' \r
folder as [II - Ucam_Webauth - Flowchart for Valid Authentication.pdf] and \r
[III - Ucam_Webauth - Flowchart for Cancelled Authentication.pdf], respectively. \r
\r
The numbers on these diagrams correspond to the three key secondary functions \r
described above:\r
- *1*. SendAuthenticationRequest()\r
- *2*. ProcessAuthenticationResponse()\r
- *3*. ProcessAuthenticationCookie()\r
\r
Other important functions include:\r
\r
### ResetState()\r
Attempts to reset state as if a new user has just loaded a fresh browser \r
window. This is typically used when a user has experienced an error and we \r
want to give them a fresh opportunity to try again. \r
\r
### check_signature(...)\r
Checks the signature provided by the Raven server, when it signed the \r
'WLS-Response' variable, is a valid signature for the data. This ensures the \r
data has not been tampered with.\r
\r
### hmac_sha1(...)\r
Creates a hash value for signing the local authentication cookie.\r
\r
### wls_encode/decode(...)\r
Encoding/decoding functions to allow base64 signatures to be sent within URLs.\r
\r
Possible arguments to 'Ucam_Webauth'\r
------------------------------------\r
(Based on documentation for PHP Raven authentication module)\r
\r
- log_file : \r
The location for a log file that will record progress and track possible \r
errors. The folder containing the file must be read/writable by the webserver.\r
Default: log.txt\r
\r
- response_timeout : \r
Responses from the central authentication server are time-stamped. \r
This parameter sets the period of time in seconds during which these \r
responses are considered valid. \r
Default: 30 seconds.\r
\r
- key_dir : \r
The name of the directory containing the public key certificate(s) required \r
to validate the authentication responses sent by the server. \r
Default: '/etc/httpd/conf/webauth_keys'.\r
\r
- max_session_life : \r
The maximum period of time in seconds for which an established session will \r
be valid. This may be overriden if the authentication reply contains a \r
shorter 'life' parameter. Note that this does NOT define an expiry time for \r
the session cookie. Session cookies are always set without an expiry time, \r
causing them to expire when the browser session finishes. \r
Default: 7200 (2 hours).\r
\r
- timeout_message : \r
A re-authentication by the authentication service will be triggered when an \r
established session expires. This option sets a text string which is sent to \r
the authentication server to explain to the user why they are being asked to \r
authenticate again. HTML markup is suppressed as for the description \r
parameter described below. \r
Default: 'your login to the site has expired'.\r
\r
- hostname (required) :\r
The fully-qualified TCP/IP hostname that should be used in request URLs \r
referencing the Ucam_Webauth-enabled application. This *must* be set, as it \r
is needed for multiple reasons - primarily security but also to avoid varying \r
hostnames in URLs leading to failed or inconsistent authentication. \r
No default.\r
\r
- cookie_key (required): \r
A random key used to protect session cookies from tampering. Any reasonably \r
unpredictable string (for example the MD5 checksum of a rapidly changing \r
logfile) will be satisfactory. This key must be the same for all uses of the \r
web authentication system that will receive the same session cookies (see the \r
cookie_name, cookie_path and cookie_domain parameters below). \r
No default.\r
\r
- cookie_name :\r
The name used for the session cookie. \r
When used for access to resources over HTTPS the string '-S' is appended to \r
this name. \r
Default: 'Ucam-Webauth-Session'.\r
\r
- cookie_path :\r
The 'Path' attribute for the session cookie. The default is the directory \r
component of the path to the script currently being executed. This should \r
result in the cookie being returned for future requests for this script and \r
for the other resources in the same 'directory'; see the important \r
information about the cookie_key parameter above. \r
Default: '/'.\r
\r
- cookie_domain :\r
The 'Domain' attribute for the session cookie. By default the 'Domain' \r
attribute is omitted when setting the cookie. This should result in the \r
cookie being returned only to the server running the script. Be aware that \r
some people may treat with suspicion cookies with domain attributes that are \r
wider than the host setting the cookie. \r
No default.\r
\r
- auth_service : The full URL for the web login service to be used. \r
Default: 'https://raven.cam.ac.uk/auth/authenticate.html' \r
\r
#### Authentication request properties\r
The following setup parameters prefixed with 'authrequest_' relate to \r
properties that will be sent to the authentication server as part of an \r
authentication request:\r
\r
- authrequest_desc : A text description of the resource that is requesting \r
authentication. This may be displayed to the user by the authentication \r
service. It is restricted to printable ASCII characters (0x20 - 0x7e) though \r
it may contain HTML entities representing other characters. The characters \r
'<' and '>' will be converted into HTML entities before being sent to the \r
browser and so this text cannot usefully contain HTML markup.\r
No default.\r
\r
- authrequest_params : Data that will be returned unaltered to the WAA in \r
any 'authentication response message' issued as a result of this request. \r
This could be used to carry the identity of the resource originally requested \r
or other WAA state, or to associate authentication requests with their \r
eventual replies. When returned, this data will be protected by the digital \r
signature applied to the authentication response message but nothing else is \r
done to ensure the integrity or confidentiality of this data - the WAA MUST \r
take responsibility for this if necessary.\r
No default.\r
\r
- authrequest_skew : Interpretation of response_timeout is difficult if the \r
clocks on the server running the PHP agent and on the authentication server \r
are out of step. Both servers should use NTP to synchronize their clocks, \r
but if they don't then this parameter should be set to an estimate of the \r
maximum expected difference between them (in seconds). \r
Default: 0.\r
\r
- authrequest_fail :\r
If TRUE, sets the fail parameter in any authentication request sent to the \r
authentication server to 'yes'. This has the effect of requiring the \r
authentication server itself to report any errors that it encounters, rather \r
than returning an error indication. Note however that even with this parameter \r
set errors may be detected by this module that will result in authentication \r
failing here. \r
Default: FALSE.\r
\r
- authrequest_iact :\r
If TRUE, then the 'iact' parameter provided to the authentication server is \r
set to 'yes'. If FALSE, then the 'iact' parameter is set to 'no'. If no value \r
is provided for 'authrequest_iact', the 'iact' parameter is left blank. \r
The value 'yes' for 'iact' requires that a re-authentication exchange takes \r
place with the user. This could be used prior to a sensitive transaction in \r
an attempt to ensure that a previously authenticated user is still present \r
at the browser. The value 'no' requires that the authentication request will \r
only succeed if the user's identity can be returned without interacting with \r
the user. This could be used as an optimisation to take advantage of any \r
existing authentication but without actively soliciting one. If omitted or \r
empty, then a previously established identity may be returned if the WLS \r
supports doing so, and if not then the user will be prompted as necessary.\r
Default: omitted.