Cookies and Spam

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Cookies and Spam
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Why cookies?

• Give a form of local storage for remote sites
• Can remember
• Name
• Time of last visit
• Store data from previous visits
• Identify page changes since you were there
• Use CGI scripts to identify user patterns through
  pages.

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How are cookies constructed

• www.buy.com FALSE / FALSE
  1034233570 buycountry us
• www.buy.com is the URL
• First FALSE says that the cookie is NOT available
  throughout the domain
• Second FALSE says that the cookie can be
  transmitted over secure and innsecure channels.
• 1034233570 gives the expiration time (in
  milliseconds since 1970)

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Sample cookies

• cm.bell-labs.com FALSE /cm/ms/who/wim
  FALSE 1215755792 count 1
• www.sendwine.com FALSE /order FALSE
  2136081693 SecureGate Yes
• .amazon.com TRUE / FALSE
  2082787201 ubid-main
  1428-1515523-803182
• .netscape.com TRUE / FALSE
  1293839999 UIDC 128.112.92.4709094306740
  76028
• yp.yahoo.com TRUE / FALSE
  1262383200 YP.us v2mcityd01Princeton
  01NJ01085400140.35530101-74.64959701501c020
  1LaJolla01CA010132.84719801-117.27330001401
  c
• tv.yahoo.com TRUE / FALSE
  1271361600 YTV lus_NJ29510v1zip08540
  
• .doubleclick.net TRUE / FALSE
  1920499187 id 63d4e550

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Cookie code
First Visit Popup Window or Splash Page Code
for index.html if (getCookie("visited")) //
if they've already been here go straight to the
content self.location.href "main.html"
else // record that they've been here
setCookie ("visited", true) On the first
visit the page is displayed and the cookie set.
The next time the visitor is forwarded to
main.html. If you use a proper setCookie() call
with an expiry date then you can have the splash
page not display again for a week, a month, a
year, .... From http//members.ozemail.com.au/dc
rombie/cookie3.html
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Building a page with a cookie

• ltHEADgt
• ltTITLEgtMy Cookie Pagelt/TITLEgt
• ltSCRIPT language"JavaScript"gt
• lt!-- Hide from older browsers
• // Original JavaScript code by Duncan Crombie
  dcrombie at chirp.com.au
• var bikky document.cookie
• function getCookie(name) // use
  getCookie("name")
• var index bikky.indexOf(name "")
• if (index -1) return null
• index bikky.indexOf("", index) 1
• var endstr bikky.indexOf("", index)
• if (endstr -1) endstr bikky.length
• return unescape(bikky.substring(index, endstr))

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Cookie code (cont.)

• var today new Date()
• var expiry new Date(today.getTime() 28 24
  60 60 1000) // plus 28 days
• function setCookie(name, value) // use
  setCookie("name", value)
• if (value ! null value ! "")
• document.cookiename "" escape(value) "
• expires" expiry.toGMTString()
• bikky document.cookie // update bikky
• // Your code goes here ...
• // Stop Hiding --gt
• lt/SCRIPTgt
• lt/HEADgt

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Spam

• Underlying assumptions for spam removal
• Humans cannot effectively send spam
• Spam contains bad words

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Spam

• Underlying assumptions for spam removal
• Humans cannot effectively send spam
• Determine if the message came from a human
• Spam contains bad words
• Block messages that contain those words

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Alan Turing 1912-1954

• PU PhD 1938
• Invented the theory underlying modern computing
  (Turing test)
• Led code breaking during WW 2 (enigma)
• Set tone for artificial intelligence with Turing
  test

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The Turing test

• Turing held that computers would in time be
  programmed to acquire abilities rivalling human
  intelligence.
• As part of his argument Turing put forward the
  idea of an 'imitation game', in which a human
  being and a computer would be interrogated under
  conditions where the interrogator would not know
  which was which, the communication being entirely
  by textual messages. Turing argued that if the
  interrogator could not distinguish them by
  questioning, then it would be unreasonable not to
  call the computer intelligent.

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Reverse turing test

• You recently sent email to dpd_at_mailblocks.net. In
  order to verify that you are a qualified email
  sender please go to http//www.mailblocks.net/conf
  irm.htm?todpduid18330 to confirm. If you have
  not confirmed within one week then your message
  will be treated as spam.

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