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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
81- 1. Ensure the 'Ucam_Webauth.vbs' class file and the folder 'js' are in the
82same directory as your ASP script. The folders 'certificates' and 'logs' may
83also be located here temporarily.
84- 2. Include the 'Ucam_Webauth.vbs' class file in the 'head' of your ASP file:
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>
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91
92- 3. Set up the initial arguments for the 'Ucam_Webauth' class:
93
94```
95Set args = CreateObject("Scripting.Dictionary")
96args.Add "hostname", "localhost"
97args.Add "auth_service", "https://demo.raven.cam.ac.uk/auth/authenticate.html"
98args.Add "key_dir", "C:/Ucam_Webauth/certificates"
99```
100
101'args' is an associative array of *text* strings so parameter values must
102be converted into strings, ie. numbers and booleans must be supplied within
103quotes as in "23", "TRUE", "FALSE".
104A full list of allowed parameters is provided at the end of this README.
105
106- 4. Create an instance of the 'Ucam_Webauth' class from within your ASP
107server page and initialize with setup variables:
108
109```
110Set oUcam_Webauth = New Ucam_Webauth
111Call oUcam_Webauth(args)
112```
113
114- 5. Call 'Authenticate()' on the Ucam_Webauth object and act according to
115the value returned:
116
117```
118 Select Case oUcam_Webauth.Authenticate()
119
120 Case oUcam_Webauth.AUTHENTICATE_INCOMPLETE
121
122 ...
123 Exit Sub
124
125 Case oUcam_Webauth.AUTHENTICATE_COMPLETE_AUTHENTICATED
126
127 ...
128
129 Case oUcam_Webauth.AUTHENTICATE_COMPLETE_NOT_AUTHENTICATED
130
131 ...
132
133 Case oUcam_Webauth.AUTHENTICATE_COMPLETE_ERROR
134
135 ...
136
137 End Select
138```
139
140The four possible return values of 'Authenticate()' are:
141
142- AUTHENTICATE_INCOMPLETE : The authentication process has yet to complete.
143The user may have been redirected to the Raven server and has yet to enter
144their login details.
145- AUTHENTICATE_COMPLETE_AUTHENTICATED : The authentication process completed
146and the user has been successfully authenticated.
147- AUTHENTICATE_COMPLETE_NOT_AUTHENTICATED : The authentication process
148completed and the user was not successfully authenticated.
149The user may have clicked 'Cancel' at the Raven server.
150- AUTHENTICATE_COMPLETE_ERROR : There was an error during the authentication
151process forcing the authentication cycle to terminate early.
152
153As the 'Authenticate()' function may need to send HTTP headers, it must be
154called before any output (e.g. HTML, HTTP headers) is sent to the browser.
155
156The 'Default.asp' file provided is a sample of a simple server page using
157the 'Ucam_Webauth' VBScript class.
158
159Overview of Raven process
160-------------------------
161A diagram of the Raven authentication process is located within the 'docs'
162folder as [I - Overview of Raven Authentication Process.pdf].
163
164The authentication cycle consists of the following key stages:
165
166#### User first tries to access authenticated page
167User tries to load an authenticated page on a particular website.
168The 'Ucam_Webauth' class is loaded and the 'Authenticate()' function is called.
169If no authentication cookie is found to indicate the user is authenticated,
170the user's browser is redirected to a separate Raven server using a special
171'Authentication Request'. The authentication request consists of a series of
172authentication parameters encoded into the URL redirect as name/value pairs.
173
174#### User is prompted for login information
175The Raven server interprets the authentication request sent by the main
176website and prompts the user for their username and password. The user may
177then be successfully authenticated or may decide to click 'Cancel'. They are
178redirected back to the main website with a series of 'Authentication Response'
179parameters encoded into a 'WLS-Response' GET variable.
180
181#### User redirected back to main webserver
182The user's original page is loaded again and 'Authenticate()' is called a
183second time. 'Ucam_Webauth' processes the new 'WLS-Response' GET value and,
184if it's valid, sets an authentication cookie on the user's browser. The
185user's original page is then loaded again.
186
187#### User redirected back to main webserver again
188With an authentication cookie now set, 'Authenticate()' checks the status
189code contained in the value of the authentication cookie and returns either
190'AUTHENTICATE_COMPLETE_AUTHENTICATED' or
191'AUTHENTICATE_COMPLETE_NOT_AUTHENTICATED'. If
192'AUTHENTICATE_COMPLETE_AUTHENTICATED' is returned , the original page can
193go on to display authenticated content to the user.
194
195Specifics of module
196-------------------
197The 'Authenticate()' function is the overarching authentication function of
198'Ucam_Webauth'. It performs some basic sanity checks using 'CheckSetup()'
199then uses 'GetCurrentState()' to establish the current state of the
200authentication process before branching accordingly. The possible return
201values of 'GetCurrentState()' are:
202
203#### STATE_NEW_AUTHENTICATION
204A completely fresh authentication. 'SendAuthenticationRequest()' [*1*] is
205then triggered which performs some basic data checks, sets the authentication
206cookie to 'AUTHENTICATIONCOOKIE_REDIRECT_WLS' (to record where we are in the
207authentication process) and redirects the user's browser to the Raven
208authentication server with a series of authentication parameters
209encoded as name/value pairs.
210
211#### STATE_WLS_RESPONSE_RECEIVED
212The Raven authentication server has processed the user and has returned the
213user's browser back to the original website with a series of authentication
214response parameters encoded into the 'WLS-Response' GET variable.
215'ProcessAuthenticationResponse()' [*2*] is then called which checks the
216validity of the 'WLS-Response' value, sets an authentication cookie and
217redirects the user back to the original page.
218
219#### STATE_WAA_AUTHENTICATIONCOOKIE_SET
220A valid authentication cookie has been set
221(<> AUTHENTICATIONCOOKIE_REDIRECT_WLS).
222'ProcessAuthenticationCookie()' [*3*] is then called which checks the
223validity of the cookie. If the cookie has expired,
224'SendAuthenticationRequest()' is called again in case the user needs to
225reauthenticate themselves. If the cookie is still valid, an
226'AUTHENTICATE_COMPLETE_XXX' value is returned, indicating that the
227authentication cycle has completed successfully.
228NOTE: this may be true if the user has cancelled the authentication process,
229in which case 'AUTHENTICATE_COMPLETE_NOT_AUTHENTICATED' will be returned.
230
231#### STATE_ERROR
232An error occurred, breaking the authentication cycle and returning
233AUTHENTICATE_COMPLETE_ERROR to 'Authenticate()'. This return value will
234also be generated by the other functions above if they generate an error.
235
236## Accompanying diagrams
237Detailed diagrams of the Raven process flow for (i) a successful
238authentication (ii) a cancelled authentication, are located in the 'docs'
239folder as [II - Ucam_Webauth - Flowchart for Valid Authentication.pdf] and
240[III - Ucam_Webauth - Flowchart for Cancelled Authentication.pdf], respectively.
241
242The numbers on these diagrams correspond to the three key secondary functions
243described above:
244- *1*. SendAuthenticationRequest()
245- *2*. ProcessAuthenticationResponse()
246- *3*. ProcessAuthenticationCookie()
247
248Other important functions include:
249
250### ResetState()
251Attempts to reset state as if a new user has just loaded a fresh browser
252window. This is typically used when a user has experienced an error and we
253want to give them a fresh opportunity to try again.
254
255### check_signature(...)
256Checks the signature provided by the Raven server, when it signed the
257'WLS-Response' variable, is a valid signature for the data. This ensures the
258data has not been tampered with.
259
260### hmac_sha1(...)
261Creates a hash value for signing the local authentication cookie.
262
263### wls_encode/decode(...)
264Encoding/decoding functions to allow base64 signatures to be sent within URLs.
265
266Possible arguments to 'Ucam_Webauth'
267------------------------------------
268(Based on documentation for PHP Raven authentication module)
269
270- log_file :
271The location for a log file that will record progress and track possible
272errors. The folder containing the file must be read/writable by the webserver.
273Default: log.txt
274
275- response_timeout :
276Responses from the central authentication server are time-stamped.
277This parameter sets the period of time in seconds during which these
278responses are considered valid.
279Default: 30 seconds.
280
281- key_dir :
282The name of the directory containing the public key certificate(s) required
283to validate the authentication responses sent by the server.
284Default: '/etc/httpd/conf/webauth_keys'.
285
286- max_session_life :
287The maximum period of time in seconds for which an established session will
288be valid. This may be overriden if the authentication reply contains a
289shorter 'life' parameter. Note that this does NOT define an expiry time for
290the session cookie. Session cookies are always set without an expiry time,
291causing them to expire when the browser session finishes.
292Default: 7200 (2 hours).
293
294- timeout_message :
295A re-authentication by the authentication service will be triggered when an
296established session expires. This option sets a text string which is sent to
297the authentication server to explain to the user why they are being asked to
298authenticate again. HTML markup is suppressed as for the description
299parameter described below.
300Default: 'your login to the site has expired'.
301
302- hostname (required) :
303The fully-qualified TCP/IP hostname that should be used in request URLs
304referencing the Ucam_Webauth-enabled application. This *must* be set, as it
305is needed for multiple reasons - primarily security but also to avoid varying
306hostnames in URLs leading to failed or inconsistent authentication.
307No default.
308
309- cookie_key (required):
310A random key used to protect session cookies from tampering. Any reasonably
311unpredictable string (for example the MD5 checksum of a rapidly changing
312logfile) will be satisfactory. This key must be the same for all uses of the
313web authentication system that will receive the same session cookies (see the
314cookie_name, cookie_path and cookie_domain parameters below).
315No default.
316
317- cookie_name :
318The name used for the session cookie.
319When used for access to resources over HTTPS the string '-S' is appended to
320this name.
321Default: 'Ucam-Webauth-Session'.
322
323- cookie_path :
324The 'Path' attribute for the session cookie. The default is the directory
325component of the path to the script currently being executed. This should
326result in the cookie being returned for future requests for this script and
327for the other resources in the same 'directory'; see the important
328information about the cookie_key parameter above.
329Default: '/'.
330
331- cookie_domain :
332The 'Domain' attribute for the session cookie. By default the 'Domain'
333attribute is omitted when setting the cookie. This should result in the
334cookie being returned only to the server running the script. Be aware that
335some people may treat with suspicion cookies with domain attributes that are
336wider than the host setting the cookie.
337No default.
338
339- auth_service : The full URL for the web login service to be used.
340Default: 'https://raven.cam.ac.uk/auth/authenticate.html'
341
342#### Authentication request properties
343The following setup parameters prefixed with 'authrequest_' relate to
344properties that will be sent to the authentication server as part of an
345authentication request:
346
347- authrequest_desc : A text description of the resource that is requesting
348authentication. This may be displayed to the user by the authentication
349service. It is restricted to printable ASCII characters (0x20 - 0x7e) though
350it may contain HTML entities representing other characters. The characters
351'<' and '>' will be converted into HTML entities before being sent to the
352browser and so this text cannot usefully contain HTML markup.
353No default.
354
355- authrequest_params : Data that will be returned unaltered to the WAA in
356any 'authentication response message' issued as a result of this request.
357This could be used to carry the identity of the resource originally requested
358or other WAA state, or to associate authentication requests with their
359eventual replies. When returned, this data will be protected by the digital
360signature applied to the authentication response message but nothing else is
361done to ensure the integrity or confidentiality of this data - the WAA MUST
362take responsibility for this if necessary.
363No default.
364
365- authrequest_skew : Interpretation of response_timeout is difficult if the
366clocks on the server running the PHP agent and on the authentication server
367are out of step. Both servers should use NTP to synchronize their clocks,
368but if they don't then this parameter should be set to an estimate of the
369maximum expected difference between them (in seconds).
370Default: 0.
371
372- authrequest_fail :
373If TRUE, sets the fail parameter in any authentication request sent to the
374authentication server to 'yes'. This has the effect of requiring the
375authentication server itself to report any errors that it encounters, rather
376than returning an error indication. Note however that even with this parameter
377set errors may be detected by this module that will result in authentication
378failing here.
379Default: FALSE.
380
381- authrequest_iact :
382If TRUE, then the 'iact' parameter provided to the authentication server is
383set to 'yes'. If FALSE, then the 'iact' parameter is set to 'no'. If no value
384is provided for 'authrequest_iact', the 'iact' parameter is left blank.
385The value 'yes' for 'iact' requires that a re-authentication exchange takes
386place with the user. This could be used prior to a sensitive transaction in
387an attempt to ensure that a previously authenticated user is still present
388at the browser. The value 'no' requires that the authentication request will
389only succeed if the user's identity can be returned without interacting with
390the user. This could be used as an optimisation to take advantage of any
391existing authentication but without actively soliciting one. If omitted or
392empty, then a previously established identity may be returned if the WLS
393supports doing so, and if not then the user will be prompted as necessary.
f560b040 394Default: omitted.