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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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93
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"
98
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99
100'args' is an associative array of *text* strings so parameter values must
101be converted into strings, ie. numbers and booleans must be supplied within
102quotes as in "23", "TRUE", "FALSE".
103A full list of allowed parameters is provided at the end of this README.
104
087f7f48 1054. Create an instance of the 'Ucam_Webauth' class from within your ASP
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106server page and initialize with setup variables:
107
108```
109Set oUcam_Webauth = New Ucam_Webauth
110Call oUcam_Webauth(args)
111```
112
087f7f48 1135. Call 'Authenticate()' on the Ucam_Webauth object and act according to
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114the value returned:
115
116```
117 Select Case oUcam_Webauth.Authenticate()
118
119 Case oUcam_Webauth.AUTHENTICATE_INCOMPLETE
120
121 ...
122 Exit Sub
123
124 Case oUcam_Webauth.AUTHENTICATE_COMPLETE_AUTHENTICATED
125
126 ...
127
128 Case oUcam_Webauth.AUTHENTICATE_COMPLETE_NOT_AUTHENTICATED
129
130 ...
131
132 Case oUcam_Webauth.AUTHENTICATE_COMPLETE_ERROR
133
134 ...
135
136 End Select
137```
138
139The four possible return values of 'Authenticate()' are:
140
141- AUTHENTICATE_INCOMPLETE : The authentication process has yet to complete.
142The user may have been redirected to the Raven server and has yet to enter
143their login details.
144- AUTHENTICATE_COMPLETE_AUTHENTICATED : The authentication process completed
145and the user has been successfully authenticated.
146- AUTHENTICATE_COMPLETE_NOT_AUTHENTICATED : The authentication process
147completed and the user was not successfully authenticated.
148The user may have clicked 'Cancel' at the Raven server.
149- AUTHENTICATE_COMPLETE_ERROR : There was an error during the authentication
150process forcing the authentication cycle to terminate early.
151
152As the 'Authenticate()' function may need to send HTTP headers, it must be
153called before any output (e.g. HTML, HTTP headers) is sent to the browser.
154
155The 'Default.asp' file provided is a sample of a simple server page using
156the 'Ucam_Webauth' VBScript class.
157
158Overview of Raven process
159-------------------------
160A diagram of the Raven authentication process is located within the 'docs'
161folder as [I - Overview of Raven Authentication Process.pdf].
162
163The authentication cycle consists of the following key stages:
164
165#### User first tries to access authenticated page
166User tries to load an authenticated page on a particular website.
167The 'Ucam_Webauth' class is loaded and the 'Authenticate()' function is called.
168If no authentication cookie is found to indicate the user is authenticated,
169the user's browser is redirected to a separate Raven server using a special
170'Authentication Request'. The authentication request consists of a series of
171authentication parameters encoded into the URL redirect as name/value pairs.
172
173#### User is prompted for login information
174The Raven server interprets the authentication request sent by the main
175website and prompts the user for their username and password. The user may
176then be successfully authenticated or may decide to click 'Cancel'. They are
177redirected back to the main website with a series of 'Authentication Response'
178parameters encoded into a 'WLS-Response' GET variable.
179
180#### User redirected back to main webserver
181The user's original page is loaded again and 'Authenticate()' is called a
182second time. 'Ucam_Webauth' processes the new 'WLS-Response' GET value and,
183if it's valid, sets an authentication cookie on the user's browser. The
184user's original page is then loaded again.
185
186#### User redirected back to main webserver again
187With an authentication cookie now set, 'Authenticate()' checks the status
188code contained in the value of the authentication cookie and returns either
189'AUTHENTICATE_COMPLETE_AUTHENTICATED' or
190'AUTHENTICATE_COMPLETE_NOT_AUTHENTICATED'. If
191'AUTHENTICATE_COMPLETE_AUTHENTICATED' is returned , the original page can
192go on to display authenticated content to the user.
193
194Specifics of module
195-------------------
196The 'Authenticate()' function is the overarching authentication function of
197'Ucam_Webauth'. It performs some basic sanity checks using 'CheckSetup()'
198then uses 'GetCurrentState()' to establish the current state of the
199authentication process before branching accordingly. The possible return
200values of 'GetCurrentState()' are:
201
202#### STATE_NEW_AUTHENTICATION
203A completely fresh authentication. 'SendAuthenticationRequest()' [*1*] is
204then triggered which performs some basic data checks, sets the authentication
205cookie to 'AUTHENTICATIONCOOKIE_REDIRECT_WLS' (to record where we are in the
206authentication process) and redirects the user's browser to the Raven
207authentication server with a series of authentication parameters
208encoded as name/value pairs.
209
210#### STATE_WLS_RESPONSE_RECEIVED
211The Raven authentication server has processed the user and has returned the
212user's browser back to the original website with a series of authentication
213response parameters encoded into the 'WLS-Response' GET variable.
214'ProcessAuthenticationResponse()' [*2*] is then called which checks the
215validity of the 'WLS-Response' value, sets an authentication cookie and
216redirects the user back to the original page.
217
218#### STATE_WAA_AUTHENTICATIONCOOKIE_SET
219A valid authentication cookie has been set
220(<> AUTHENTICATIONCOOKIE_REDIRECT_WLS).
221'ProcessAuthenticationCookie()' [*3*] is then called which checks the
222validity of the cookie. If the cookie has expired,
223'SendAuthenticationRequest()' is called again in case the user needs to
224reauthenticate themselves. If the cookie is still valid, an
225'AUTHENTICATE_COMPLETE_XXX' value is returned, indicating that the
226authentication cycle has completed successfully.
227NOTE: this may be true if the user has cancelled the authentication process,
228in which case 'AUTHENTICATE_COMPLETE_NOT_AUTHENTICATED' will be returned.
229
230#### STATE_ERROR
231An error occurred, breaking the authentication cycle and returning
232AUTHENTICATE_COMPLETE_ERROR to 'Authenticate()'. This return value will
233also be generated by the other functions above if they generate an error.
234
235## Accompanying diagrams
236Detailed diagrams of the Raven process flow for (i) a successful
237authentication (ii) a cancelled authentication, are located in the 'docs'
238folder as [II - Ucam_Webauth - Flowchart for Valid Authentication.pdf] and
239[III - Ucam_Webauth - Flowchart for Cancelled Authentication.pdf], respectively.
240
241The numbers on these diagrams correspond to the three key secondary functions
242described above:
243- *1*. SendAuthenticationRequest()
244- *2*. ProcessAuthenticationResponse()
245- *3*. ProcessAuthenticationCookie()
246
247Other important functions include:
248
249### ResetState()
250Attempts to reset state as if a new user has just loaded a fresh browser
251window. This is typically used when a user has experienced an error and we
252want to give them a fresh opportunity to try again.
253
254### check_signature(...)
255Checks the signature provided by the Raven server, when it signed the
256'WLS-Response' variable, is a valid signature for the data. This ensures the
257data has not been tampered with.
258
259### hmac_sha1(...)
260Creates a hash value for signing the local authentication cookie.
261
262### wls_encode/decode(...)
263Encoding/decoding functions to allow base64 signatures to be sent within URLs.
264
265Possible arguments to 'Ucam_Webauth'
266------------------------------------
267(Based on documentation for PHP Raven authentication module)
268
269- log_file :
270The location for a log file that will record progress and track possible
271errors. The folder containing the file must be read/writable by the webserver.
272Default: log.txt
273
274- response_timeout :
275Responses from the central authentication server are time-stamped.
276This parameter sets the period of time in seconds during which these
277responses are considered valid.
278Default: 30 seconds.
279
280- key_dir :
281The name of the directory containing the public key certificate(s) required
282to validate the authentication responses sent by the server.
283Default: '/etc/httpd/conf/webauth_keys'.
284
285- max_session_life :
286The maximum period of time in seconds for which an established session will
287be valid. This may be overriden if the authentication reply contains a
288shorter 'life' parameter. Note that this does NOT define an expiry time for
289the session cookie. Session cookies are always set without an expiry time,
290causing them to expire when the browser session finishes.
291Default: 7200 (2 hours).
292
293- timeout_message :
294A re-authentication by the authentication service will be triggered when an
295established session expires. This option sets a text string which is sent to
296the authentication server to explain to the user why they are being asked to
297authenticate again. HTML markup is suppressed as for the description
298parameter described below.
299Default: 'your login to the site has expired'.
300
301- hostname (required) :
302The fully-qualified TCP/IP hostname that should be used in request URLs
303referencing the Ucam_Webauth-enabled application. This *must* be set, as it
304is needed for multiple reasons - primarily security but also to avoid varying
305hostnames in URLs leading to failed or inconsistent authentication.
306No default.
307
308- cookie_key (required):
309A random key used to protect session cookies from tampering. Any reasonably
310unpredictable string (for example the MD5 checksum of a rapidly changing
311logfile) will be satisfactory. This key must be the same for all uses of the
312web authentication system that will receive the same session cookies (see the
313cookie_name, cookie_path and cookie_domain parameters below).
314No default.
315
316- cookie_name :
317The name used for the session cookie.
318When used for access to resources over HTTPS the string '-S' is appended to
319this name.
320Default: 'Ucam-Webauth-Session'.
321
322- cookie_path :
323The 'Path' attribute for the session cookie. The default is the directory
324component of the path to the script currently being executed. This should
325result in the cookie being returned for future requests for this script and
326for the other resources in the same 'directory'; see the important
327information about the cookie_key parameter above.
328Default: '/'.
329
330- cookie_domain :
331The 'Domain' attribute for the session cookie. By default the 'Domain'
332attribute is omitted when setting the cookie. This should result in the
333cookie being returned only to the server running the script. Be aware that
334some people may treat with suspicion cookies with domain attributes that are
335wider than the host setting the cookie.
336No default.
337
338- auth_service : The full URL for the web login service to be used.
339Default: 'https://raven.cam.ac.uk/auth/authenticate.html'
340
341#### Authentication request properties
342The following setup parameters prefixed with 'authrequest_' relate to
343properties that will be sent to the authentication server as part of an
344authentication request:
345
346- authrequest_desc : A text description of the resource that is requesting
347authentication. This may be displayed to the user by the authentication
348service. It is restricted to printable ASCII characters (0x20 - 0x7e) though
349it may contain HTML entities representing other characters. The characters
350'<' and '>' will be converted into HTML entities before being sent to the
351browser and so this text cannot usefully contain HTML markup.
352No default.
353
354- authrequest_params : Data that will be returned unaltered to the WAA in
355any 'authentication response message' issued as a result of this request.
356This could be used to carry the identity of the resource originally requested
357or other WAA state, or to associate authentication requests with their
358eventual replies. When returned, this data will be protected by the digital
359signature applied to the authentication response message but nothing else is
360done to ensure the integrity or confidentiality of this data - the WAA MUST
361take responsibility for this if necessary.
362No default.
363
364- authrequest_skew : Interpretation of response_timeout is difficult if the
365clocks on the server running the PHP agent and on the authentication server
366are out of step. Both servers should use NTP to synchronize their clocks,
367but if they don't then this parameter should be set to an estimate of the
368maximum expected difference between them (in seconds).
369Default: 0.
370
371- authrequest_fail :
372If TRUE, sets the fail parameter in any authentication request sent to the
373authentication server to 'yes'. This has the effect of requiring the
374authentication server itself to report any errors that it encounters, rather
375than returning an error indication. Note however that even with this parameter
376set errors may be detected by this module that will result in authentication
377failing here.
378Default: FALSE.
379
380- authrequest_iact :
381If TRUE, then the 'iact' parameter provided to the authentication server is
382set to 'yes'. If FALSE, then the 'iact' parameter is set to 'no'. If no value
383is provided for 'authrequest_iact', the 'iact' parameter is left blank.
384The value 'yes' for 'iact' requires that a re-authentication exchange takes
385place with the user. This could be used prior to a sensitive transaction in
386an attempt to ensure that a previously authenticated user is still present
387at the browser. The value 'no' requires that the authentication request will
388only succeed if the user's identity can be returned without interacting with
389the user. This could be used as an optimisation to take advantage of any
390existing authentication but without actively soliciting one. If omitted or
391empty, then a previously established identity may be returned if the WLS
392supports doing so, and if not then the user will be prompted as necessary.
f560b040 393Default: omitted.