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[raven/abandoned/asp.git] / README.md
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1University of Cambridge Classic ASP/VBScript Raven Authentication Module - v.1.0 (29/04/2014)
2==========================================================================
3
4Description
5-----------
6This software comprises a VBScript class 'Ucam_Webauth' and sample
7files that provide a Classic ASP/VBScript implementation of a 'Raven'
8authentication module; Raven is the web authentication protocol used
9by the University of Cambridge, UK. The logic and code of the
10'Ucam_Webauth' class are loosely based on the PHP Raven authentication
11class provided at http://raven.cam.ac.uk/project/.
12- For a full description of the latest Raven specification and an explanation
13of how Raven works, go to http://raven.cam.ac.uk/project/.
14- This software was originally created for the Careers Service,
15University of Cambridge by sh801@cam.ac.uk. For support, please
16contact raven-support@ucs.cam.ac.uk
17
18Files and folders
19-----------------
20- [certificates]: Temporary location for Raven public key certificates.
21- [js]: Folder containing Javascript cryptography libraries.
22- [docs]: Supporting documentation.
23- [logs]: Possible location for log files created by the module.
24- Default.asp: A sample file showing how the 'Ucam_Webauth' class is used
25to provide Raven authentication.
26- Test.asp: A test file for unit testing the 'Ucam_Webauth' module using the
27'Ucam_RavenWLS' dummy Raven server (separate project, not included).
28- Ucam_Webauth.vbs: The main 'Ucam_Webauth' VBScript class.
29
30Platform requirements
31---------------------
32This module has been tested on IIS7 with .NET Framework set to
33'No managed code', ie. classic ASP.
34
35Installation
36------------
37### Cryptographic functions
38Cryptographic functions are provided by the Javascript libraries within the
39'js' folder. These libraries are versions of the client-side Javascript
40libraries provided at http://kjur.github.io/jsrsasign/index.html
41but modified to run server-side. There is no need to install any
42additional cryptography libraries.
43
44### Install Raven certificates
45The authentication module uses the Raven public key certificate at
46https://raven.cam.ac.uk/project/keys/ to verify authentication responses.
47Download the certificate from https://raven.cam.ac.uk/project/keys/ and copy
48to the 'certificates' folder provided with this authentication module
49download - the 'certificates' folder is a temporary location for the
50certificate while you get the module up and running. You will need to supply
51the full path to the 'certificates' folder as either a 'key_dir' argument
52to the 'Ucam_Webauth' constructor or by modifying the 'Ucam_Webauth'
53variable 'DEFAULT_KEY_DIR' directly.
54
55Once you have everything working, move the 'certificates' folder
56to a new location on your webserver that is not web- or publicly-accessible
57and modify the 'key_dir' string accordingly.
58
59- NOTE: you may have to change the name of the key file from 'pubkey2.crt'
60to '2.crt'.
61
62If you're using the Raven test server
63(http://raven.cam.ac.uk/project/test-demo/) for testing purposes, make sure
64you install the test server keys instead, but ensure you remove these keys
65before using the authentication module in a production environment, as
66recommended by the demo Raven server:
67
68> It is vital to keep these demo keys seperate from keys
69> used with a production service - failure to do so could
70> allow an attacker to successfully replay a response
71> from the demonstration server, which anyone can easily
72> obtain, against a production service.
73
74Getting started
75---------------
76
77The 'Ucam_Webauth' VBScript class must be used within an ASP server-side page
78as it interacts directly with a user's browser session. To use the
79'Ucam_Webauth' VBScript class:
80
087f7f48 811. Ensure the 'Ucam_Webauth.vbs' class file and the folder 'js' are in the
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82same directory as your ASP script. The folders 'certificates' and 'logs' may
83also be located here temporarily.
087f7f48 842. Include the 'Ucam_Webauth.vbs' class file in the 'head' of your ASP file:
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85
86
0f462a18 87 <head>
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88 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
89 <!--#include file="Ucam_Webauth.vbs"-->
90 </head>
2ffb56d1 91
087f7f48 923. Set up the initial arguments for the 'Ucam_Webauth' class:
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94 Set args = CreateObject("Scripting.Dictionary")
95 args.Add "hostname", "localhost"
96 args.Add "auth_service", "https://demo.raven.cam.ac.uk/auth/authenticate.html"
97 args.Add "key_dir", "C:/Ucam_Webauth/certificates"
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98
99'args' is an associative array of *text* strings so parameter values must
100be converted into strings, ie. numbers and booleans must be supplied within
101quotes as in "23", "TRUE", "FALSE".
102A full list of allowed parameters is provided at the end of this README.
103
087f7f48 1044. Create an instance of the 'Ucam_Webauth' class from within your ASP
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105server page and initialize with setup variables:
106
107```
108Set oUcam_Webauth = New Ucam_Webauth
109Call oUcam_Webauth(args)
110```
111
087f7f48 1125. Call 'Authenticate()' on the Ucam_Webauth object and act according to
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113the value returned:
114
115```
116 Select Case oUcam_Webauth.Authenticate()
117
118 Case oUcam_Webauth.AUTHENTICATE_INCOMPLETE
119
120 ...
121 Exit Sub
122
123 Case oUcam_Webauth.AUTHENTICATE_COMPLETE_AUTHENTICATED
124
125 ...
126
127 Case oUcam_Webauth.AUTHENTICATE_COMPLETE_NOT_AUTHENTICATED
128
129 ...
130
131 Case oUcam_Webauth.AUTHENTICATE_COMPLETE_ERROR
132
133 ...
134
135 End Select
136```
137
138The four possible return values of 'Authenticate()' are:
139
140- AUTHENTICATE_INCOMPLETE : The authentication process has yet to complete.
141The user may have been redirected to the Raven server and has yet to enter
142their login details.
143- AUTHENTICATE_COMPLETE_AUTHENTICATED : The authentication process completed
144and the user has been successfully authenticated.
145- AUTHENTICATE_COMPLETE_NOT_AUTHENTICATED : The authentication process
146completed and the user was not successfully authenticated.
147The user may have clicked 'Cancel' at the Raven server.
148- AUTHENTICATE_COMPLETE_ERROR : There was an error during the authentication
149process forcing the authentication cycle to terminate early.
150
151As the 'Authenticate()' function may need to send HTTP headers, it must be
152called before any output (e.g. HTML, HTTP headers) is sent to the browser.
153
154The 'Default.asp' file provided is a sample of a simple server page using
155the 'Ucam_Webauth' VBScript class.
156
157Overview of Raven process
158-------------------------
159A diagram of the Raven authentication process is located within the 'docs'
160folder as [I - Overview of Raven Authentication Process.pdf].
161
162The authentication cycle consists of the following key stages:
163
164#### User first tries to access authenticated page
165User tries to load an authenticated page on a particular website.
166The 'Ucam_Webauth' class is loaded and the 'Authenticate()' function is called.
167If no authentication cookie is found to indicate the user is authenticated,
168the user's browser is redirected to a separate Raven server using a special
169'Authentication Request'. The authentication request consists of a series of
170authentication parameters encoded into the URL redirect as name/value pairs.
171
172#### User is prompted for login information
173The Raven server interprets the authentication request sent by the main
174website and prompts the user for their username and password. The user may
175then be successfully authenticated or may decide to click 'Cancel'. They are
176redirected back to the main website with a series of 'Authentication Response'
177parameters encoded into a 'WLS-Response' GET variable.
178
179#### User redirected back to main webserver
180The user's original page is loaded again and 'Authenticate()' is called a
181second time. 'Ucam_Webauth' processes the new 'WLS-Response' GET value and,
182if it's valid, sets an authentication cookie on the user's browser. The
183user's original page is then loaded again.
184
185#### User redirected back to main webserver again
186With an authentication cookie now set, 'Authenticate()' checks the status
187code contained in the value of the authentication cookie and returns either
188'AUTHENTICATE_COMPLETE_AUTHENTICATED' or
189'AUTHENTICATE_COMPLETE_NOT_AUTHENTICATED'. If
190'AUTHENTICATE_COMPLETE_AUTHENTICATED' is returned , the original page can
191go on to display authenticated content to the user.
192
193Specifics of module
194-------------------
195The 'Authenticate()' function is the overarching authentication function of
196'Ucam_Webauth'. It performs some basic sanity checks using 'CheckSetup()'
197then uses 'GetCurrentState()' to establish the current state of the
198authentication process before branching accordingly. The possible return
199values of 'GetCurrentState()' are:
200
201#### STATE_NEW_AUTHENTICATION
202A completely fresh authentication. 'SendAuthenticationRequest()' [*1*] is
203then triggered which performs some basic data checks, sets the authentication
204cookie to 'AUTHENTICATIONCOOKIE_REDIRECT_WLS' (to record where we are in the
205authentication process) and redirects the user's browser to the Raven
206authentication server with a series of authentication parameters
207encoded as name/value pairs.
208
209#### STATE_WLS_RESPONSE_RECEIVED
210The Raven authentication server has processed the user and has returned the
211user's browser back to the original website with a series of authentication
212response parameters encoded into the 'WLS-Response' GET variable.
213'ProcessAuthenticationResponse()' [*2*] is then called which checks the
214validity of the 'WLS-Response' value, sets an authentication cookie and
215redirects the user back to the original page.
216
217#### STATE_WAA_AUTHENTICATIONCOOKIE_SET
218A valid authentication cookie has been set
219(<> AUTHENTICATIONCOOKIE_REDIRECT_WLS).
220'ProcessAuthenticationCookie()' [*3*] is then called which checks the
221validity of the cookie. If the cookie has expired,
222'SendAuthenticationRequest()' is called again in case the user needs to
223reauthenticate themselves. If the cookie is still valid, an
224'AUTHENTICATE_COMPLETE_XXX' value is returned, indicating that the
225authentication cycle has completed successfully.
226NOTE: this may be true if the user has cancelled the authentication process,
227in which case 'AUTHENTICATE_COMPLETE_NOT_AUTHENTICATED' will be returned.
228
229#### STATE_ERROR
230An error occurred, breaking the authentication cycle and returning
231AUTHENTICATE_COMPLETE_ERROR to 'Authenticate()'. This return value will
232also be generated by the other functions above if they generate an error.
233
234## Accompanying diagrams
235Detailed diagrams of the Raven process flow for (i) a successful
236authentication (ii) a cancelled authentication, are located in the 'docs'
237folder as [II - Ucam_Webauth - Flowchart for Valid Authentication.pdf] and
238[III - Ucam_Webauth - Flowchart for Cancelled Authentication.pdf], respectively.
239
240The numbers on these diagrams correspond to the three key secondary functions
241described above:
242- *1*. SendAuthenticationRequest()
243- *2*. ProcessAuthenticationResponse()
244- *3*. ProcessAuthenticationCookie()
245
246Other important functions include:
247
248### ResetState()
249Attempts to reset state as if a new user has just loaded a fresh browser
250window. This is typically used when a user has experienced an error and we
251want to give them a fresh opportunity to try again.
252
253### check_signature(...)
254Checks the signature provided by the Raven server, when it signed the
255'WLS-Response' variable, is a valid signature for the data. This ensures the
256data has not been tampered with.
257
258### hmac_sha1(...)
259Creates a hash value for signing the local authentication cookie.
260
261### wls_encode/decode(...)
262Encoding/decoding functions to allow base64 signatures to be sent within URLs.
263
264Possible arguments to 'Ucam_Webauth'
265------------------------------------
266(Based on documentation for PHP Raven authentication module)
267
268- log_file :
269The location for a log file that will record progress and track possible
270errors. The folder containing the file must be read/writable by the webserver.
271Default: log.txt
272
273- response_timeout :
274Responses from the central authentication server are time-stamped.
275This parameter sets the period of time in seconds during which these
276responses are considered valid.
277Default: 30 seconds.
278
279- key_dir :
280The name of the directory containing the public key certificate(s) required
281to validate the authentication responses sent by the server.
282Default: '/etc/httpd/conf/webauth_keys'.
283
284- max_session_life :
285The maximum period of time in seconds for which an established session will
286be valid. This may be overriden if the authentication reply contains a
287shorter 'life' parameter. Note that this does NOT define an expiry time for
288the session cookie. Session cookies are always set without an expiry time,
289causing them to expire when the browser session finishes.
290Default: 7200 (2 hours).
291
292- timeout_message :
293A re-authentication by the authentication service will be triggered when an
294established session expires. This option sets a text string which is sent to
295the authentication server to explain to the user why they are being asked to
296authenticate again. HTML markup is suppressed as for the description
297parameter described below.
298Default: 'your login to the site has expired'.
299
300- hostname (required) :
301The fully-qualified TCP/IP hostname that should be used in request URLs
302referencing the Ucam_Webauth-enabled application. This *must* be set, as it
303is needed for multiple reasons - primarily security but also to avoid varying
304hostnames in URLs leading to failed or inconsistent authentication.
305No default.
306
307- cookie_key (required):
308A random key used to protect session cookies from tampering. Any reasonably
309unpredictable string (for example the MD5 checksum of a rapidly changing
310logfile) will be satisfactory. This key must be the same for all uses of the
311web authentication system that will receive the same session cookies (see the
312cookie_name, cookie_path and cookie_domain parameters below).
313No default.
314
315- cookie_name :
316The name used for the session cookie.
317When used for access to resources over HTTPS the string '-S' is appended to
318this name.
319Default: 'Ucam-Webauth-Session'.
320
321- cookie_path :
322The 'Path' attribute for the session cookie. The default is the directory
323component of the path to the script currently being executed. This should
324result in the cookie being returned for future requests for this script and
325for the other resources in the same 'directory'; see the important
326information about the cookie_key parameter above.
327Default: '/'.
328
329- cookie_domain :
330The 'Domain' attribute for the session cookie. By default the 'Domain'
331attribute is omitted when setting the cookie. This should result in the
332cookie being returned only to the server running the script. Be aware that
333some people may treat with suspicion cookies with domain attributes that are
334wider than the host setting the cookie.
335No default.
336
337- auth_service : The full URL for the web login service to be used.
338Default: 'https://raven.cam.ac.uk/auth/authenticate.html'
339
340#### Authentication request properties
341The following setup parameters prefixed with 'authrequest_' relate to
342properties that will be sent to the authentication server as part of an
343authentication request:
344
345- authrequest_desc : A text description of the resource that is requesting
346authentication. This may be displayed to the user by the authentication
347service. It is restricted to printable ASCII characters (0x20 - 0x7e) though
348it may contain HTML entities representing other characters. The characters
349'<' and '>' will be converted into HTML entities before being sent to the
350browser and so this text cannot usefully contain HTML markup.
351No default.
352
353- authrequest_params : Data that will be returned unaltered to the WAA in
354any 'authentication response message' issued as a result of this request.
355This could be used to carry the identity of the resource originally requested
356or other WAA state, or to associate authentication requests with their
357eventual replies. When returned, this data will be protected by the digital
358signature applied to the authentication response message but nothing else is
359done to ensure the integrity or confidentiality of this data - the WAA MUST
360take responsibility for this if necessary.
361No default.
362
363- authrequest_skew : Interpretation of response_timeout is difficult if the
364clocks on the server running the PHP agent and on the authentication server
365are out of step. Both servers should use NTP to synchronize their clocks,
366but if they don't then this parameter should be set to an estimate of the
367maximum expected difference between them (in seconds).
368Default: 0.
369
370- authrequest_fail :
371If TRUE, sets the fail parameter in any authentication request sent to the
372authentication server to 'yes'. This has the effect of requiring the
373authentication server itself to report any errors that it encounters, rather
374than returning an error indication. Note however that even with this parameter
375set errors may be detected by this module that will result in authentication
376failing here.
377Default: FALSE.
378
379- authrequest_iact :
380If TRUE, then the 'iact' parameter provided to the authentication server is
381set to 'yes'. If FALSE, then the 'iact' parameter is set to 'no'. If no value
382is provided for 'authrequest_iact', the 'iact' parameter is left blank.
383The value 'yes' for 'iact' requires that a re-authentication exchange takes
384place with the user. This could be used prior to a sensitive transaction in
385an attempt to ensure that a previously authenticated user is still present
386at the browser. The value 'no' requires that the authentication request will
387only succeed if the user's identity can be returned without interacting with
388the user. This could be used as an optimisation to take advantage of any
389existing authentication but without actively soliciting one. If omitted or
390empty, then a previously established identity may be returned if the WLS
391supports doing so, and if not then the user will be prompted as necessary.
f560b040 392Default: omitted.