Introduction to P3P

1
Introduction to P3P

• Week 6 - October 3, 5

2
Original Idea behind P3P
P3P Introduction

• A framework for automated privacy discussions
• Web sites disclose their privacy practices in
  standard machine-readable formats
• Web browsers automatically retrieve P3P privacy
  policies and compare them to users privacy
  preferences
• Sites and browsers can then negotiate about
  privacy terms

3
P3P history
P3P Introduction

• Idea discussed at November 1995 FTC meeting
• Ad Hoc Internet Privacy Working Group convened
  to discuss the idea in Fall 1996
• W3C began working on P3P in Summer 1997
• Several working groups chartered with dozens of
  participants from industry, non-profits,
  academia, government
• Numerous public working drafts issued, and
  feedback resulted in many changes
• Early ideas about negotiation and agreement
  ultimately removed
• Automatic data transfer added and then removed
• Patent issue stalled progress, but ultimately
  became non-issue
• P3P issued as official W3C Recommendation on
  April 16, 2002
• http//www.w3.org/TR/P3P/

4
P3P1.0 A first step
P3P Introduction

• Offers an easy way for web sites to communicate
  about their privacy policies in a standard
  machine-readable format
• Can be deployed using existing web servers
• This will enable the development of tools that
• Provide snapshots of sites policies
• Compare policies with user preferences
• Alert and advise the user

5
P3P is part of the solution
P3P Introduction

• P3P1.0 helps users understand privacy policies
  but is not a complete solution
• Seal programs and regulations
• help ensure that sites comply with their policies
• Anonymity tools
• reduce the amount of information revealed while
  browsing
• Encryption tools
• secure data in transit and storage
• Laws and codes of practice
• provide a base line level for acceptable policies

6
The basics
P3P Introduction

• P3P provides a standard XML format that web sites
  use to encode their privacy policies
• Sites also provide XML policy reference files
  to indicate which policy applies to which part of
  the site
• Sites can optionally provide a compact policy
  by configuring their servers to issue a special
  P3P header when cookies are set
• No special server software required
• User software to read P3P policies called a P3P
  user agent

7
P3P1.0 Spec Defines
P3P Introduction

• A standard vocabulary for describing set of uses,
  recipients, data categories, and other privacy
  disclosures
• A standard schema for data a Web site may wish to
  collect (base data schema)
• An XML format for expressing a privacy policy in
  a machine readable way
• A means of associating privacy policies with Web
  pages or sites
• A protocol for transporting P3P policies over HTTP

8
A simple HTTP transaction
P3P Introduction
WebServer
9
with P3P 1.0 added
P3P Introduction
WebServer
10
Transparency
P3P Introduction

• P3P clients can check a privacy policy each time
  it changes
• P3P clients can check privacy policies on all
  objects in a web page, including ads and
  invisible images

http//www.att.com/accessatt/
http//adforce.imgis.com/?adlink2685231146ADF
ORCE
11
P3P in IE6
P3P Introduction
Automatic processing of compact policies
only third-party cookies without compact
policies blocked by default
Privacy icon on status bar indicates that a
cookie has been blocked pop-up appears the
first time the privacy icon appears
12
P3P Introduction
Users can click on privacy icon forlist of
cookies privacy summariesare available
atsites that are P3P-enabled
13
P3P Introduction
Privacy summary report isgenerated
automaticallyfrom full P3P policy
14
P3P in Netscape 7
P3P Introduction
Preview version similar to IE6, focusing, on
cookies cookies without compact policies (both
first-party and third-party) are flagged rather
than blocked by default
Indicates flagged cookie
15
P3P Introduction
Users can view English translation of (part of)
compact policy in Cookie Manager
16
P3P Introduction
A policy summary can be generated automatically
from full P3P policy
17
ATT Privacy Bird
P3P Introduction

• Free download of beta from http//www.privacybird.
  com/
• Browser helper object forIE 5.01/5.5/6.0
• Reads P3P policies at all P3P-enabled sites
  automatically
• Puts bird icon at top of browser window that
  changes to indicate whether site matches users
  privacy preferences
• Clicking on bird icon gives more information
• Current version is information only no cookie
  blocking

18
Chirping bird is privacy indicator
P3P Introduction
19
Click on the bird for more info
P3P Introduction
20
Privacy policy summary - mismatch
P3P Introduction
21
Users select warning conditions
P3P Introduction
22
Bird checks policies for embedded content
P3P Introduction
23
P3P deployment overview
P3P Enabling your web site overview and options

1. Create a privacy policy
2. Analyze the use of cookies and third-party
   content on your site
3. Determine whether you want to have one P3P policy
   for your entire site or different P3P policies
   for different parts of your site
4. Create a P3P policy (or policies) for your site
5. Create a policy reference file for your site
6. Configure your server for P3P
7. Test your site to make sure it is properly P3P
   enabled

24
Whats in a P3P policy?
P3P Enabling your web site overview and options

• Name and contact information for site
• The kind of access provided
• Mechanisms for resolving privacy disputes
• The kinds of data collected
• How collected data is used, and whether
  individuals can opt-in or opt-out of any of these
  uses
• Whether/when data may be shared and whether there
  is opt-in or opt-out
• Data retention policy

25
One policy or many?
P3P Enabling your web site overview and options

• P3P allows policies to be specified for
  individual URLs or cookies
• One policy for entire web site (all URLs and
  cookies) is easiest to manage
• Multiple policies can allow more specific
  declarations about particular parts of the site
• Multiple policies may be needed if different
  parts of the site have different owners or
  responsible parties (universities, CDNs, etc.)

26
Third-party content
P3P Enabling your web site overview and options

• Third-party content should be P3P-enabled by the
  third-party
• If third-party content sets cookies, IE6 will
  block them by default unless they have P3P
  compact policy
• Your first-party cookies may become third-party
  cookies if your site is framed by another site, a
  page is sent via email, etc.

27
Cookies and P3P
P3P Enabling your web site overview and options

• P3P policies must declare all the data stored in
  a cookie as well as any data linked via the
  cookie
• P3P policies must declare all uses of stored and
  linked cookie data
• Sites should not declare cookie-specific policies
  unless they are sure they know where their
  cookies are going!
• Watch out for domain-level cookies
• Most sites will declare broad policy that covers
  both URLs and cookies

28
Generating a P3P policy
P3P Enabling your web site overview and options

• Edit by hand
• Cut and paste from an example
• Use a P3P policy generator
• Recommended IBM P3P policy editorhttp//www.alph
  aworks.ibm.com/tech/p3peditor
• Generate compact policy and policy reference file
  the same way (by hand or with policy editor)
• Get a book
• Web Privacy with P3Pby Lorrie Faith
  Cranorhttp//p3pbook.com/

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IBM P3P Policy Editor
P3P Enabling your web site overview and options
Sites can list the typesof data theycollect
VI. P3P Deployment Client Examples
And view the correspondingP3P policy
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Locating the policy reference file
P3P Enabling your web site overview and options

• Place policy reference file in well known
  location /w3c/p3p.xml
• Most sites will do this
• Use special P3P HTTP header
• Recommended only for sites with unusual
  circumstances, such as those with many P3P
  policies
• Embed link tags in HTML files
• Recommended only for sites that exist as a
  directory on somebody elses server (for example,
  a personal home page)

31
Compact policies
P3P Enabling your web site overview and options

• HTTP header with short summary of full P3P policy
  for cookies (not for URLs)
• Not required
• Must be used in addition to full policy
• Must commit to following policy for lifetime of
  cookies
• May over simplify sites policy
• IE6 relies heavily on compact policies for cookie
  filtering especially an issue for third-party
  cookies

32
Server configuration
P3P Enabling your web site overview and options

• Only needed for compact policies and/or sites
  that use P3P HTTP header
• Need to configure server to insert extra headers
• Procedure depends on server see P3P Deployment
  Guide appendix http//www.w3.org/TR/p3pdeployment
  or Appendix B of Web Privacy with P3P

33
Dont forget to test!
P3P Enabling your web site overview and options

• Make sure you use the P3P validator to check for
  syntax errors and make sure files are in the
  right place http//www.w3.org/P3P/validator/
• But validator cant tell whether your policy is
  accurate
• Use P3P user agents to view your policy and read
  their policy summaries carefully
• Test multiple pages on your site

34
XML syntax basics
P3P Policy syntax
Element opening tag

• ltBIG-ELEMENTgt ltelement name"value"
  /gtlt/BIG-ELEMENTgtlt!-- This is a comment
  --gtltELEMENTgtSometimes data goesbetween opening
  and closing tagslt/ELEMENTgt

Attribute
Element thatdoesnt contain other
elements(ending slash)
Comment
Element closing tag(beginningslash)
Element that contains character data
35
Assertions in a P3P policy
P3P Policy syntax

• General assertions
• Location of human-readable policies and opt-out
  mechanisms discuri, opturi attributes of
  ltPOLICYgt
• Indication that policy is for testing only
  ltTESTgt (optional)
• Web site contact information ltENTITYgt
• Access information ltACCESSgt
• Information about dispute resolution ltDISPUTESgt
  (optional)
• Data-Specific Assertions
• Consequence of providing data ltCONSEQUENCEgt
  (optional)
• Indication that no identifiable data is collected
  ltNON-IDENTIFIABLEgt (optional)
• How data will be used ltPURPOSEgt
• With whom data may be shared ltRECIPIENTgt
• Whether opt-in and/or opt-out is available
  required attribute of ltPURPOSEgt and ltRECIPIENTgt
• Data retention policy ltRETENTIONgt
• What kind of data is collected ltDATAgt

36
Structure of a P3P policy
POLICY
POLICY attributes
TEST
ENTITY
ACCESS
DISPUTES-GROUP
STATEMENT
additionalSTATEMENT elements
mandatory element
optional element (not all optional elements
are shown)
37
Example privacy policy
P3P Policy syntax

• We do not currently collect any information
  from visitors to this site except the information
  contained in standard web server logs (your IP
  address, referer, information about your web
  browser, information about your HTTP requests,
  etc.). The information in these logs will be used
  only by us and the server administrators for
  website and system administration, and for
  improving this site. It will not be disclosed
  unless required by law. We may retain these log
  files indefinitely. Please direct questions about
  this privacy policy to privacy_at_p3pbook.com.

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P3P/XML encoding
P3P Policy syntax
ltPOLICIES xmlns"http//www.w3.org/2002/01/P3Pv1"gt
ltPOLICY discuri"http//p3pbook.com/privacy.html"
name"policy"gt ltENTITYgt
ltDATA-GROUPgt ltDATA ref"business.contac
t-info.online.email"gtprivacy_at_p3pbook.com
lt/DATAgt ltDATA ref"business.contact-in
fo.online.uri"gthttp//p3pbook.com/ lt/DATAgt
ltDATA ref"business.name"gtWeb Privacy With
P3Plt/DATAgt lt/DATA-GROUPgt lt/ENTITYgt
ltACCESSgtltnonident/gtlt/ACCESSgt ltSTATEMENTgt
ltCONSEQUENCEgtWe keep standard web server
logs.lt/CONSEQUENCEgt ltPURPOSEgtltadmin/gtltcurrent/
gtltdevelop/gtlt/PURPOSEgt ltRECIPIENTgtltours/gtlt/RECI
PIENTgt ltRETENTIONgtltindefinitely/gtlt/RETENTIONgt
ltDATA-GROUPgt ltDATA ref"dynamic.clicks
tream"/gt ltDATA ref"dynamic.http"/gt
lt/DATA-GROUPgt lt/STATEMENTgt lt/POLICYgt lt/POLICIESgt
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The POLICY element
P3P Policy syntax

• Example
• ltPOLICY name"general-p3p-policy"
  discuri"http//www.example.com/privacy.html"
  opturi"http//www.example.com/opt-out.html"gt

• Contains a complete P3P policy
• Takes mandatory discuri attribute
• indicates location of human-readable privacy
  policy
• Takes opturi attribute (mandatory for sites with
  opt-in or opt-out)
• Indicates location of opt-in/opt-out policy
• Takes mandatory name attribute
• Sub-Elements
• ltEXTENSIONgt, ltTESTgt, ltEXPIRYgt, ltDATASCHEMAgt,
  ltENTITYgt, ltACCESSgt, ltDISPUTES-GROUPgt,
  ltSTATEMENTgt, ltEXTENSIONgt

40
The TEST element
P3P Policy syntax

• Used for testing purposes
• Presence indicates that policy is for testing
  purposes and MUST be ignored
• Prevents misunderstandings during initial P3P
  deployment
• ltTEST/gt

41
The ENTITY element
P3P Policy syntax

• Identifies the legal entity making the
  representation of the privacy practices contained
  in the policy
• Uses the business.name data element and
  (optionally) other fields in the business data
  set (at least one piece of contact info required)
• Example
• ltENTITYgtltDATA-GROUPgt ltDATA
  ref"business.name"gtCatalogExamplelt/DATAgt
  ltDATA ref"business.contact-info.telecom.telephon
  e. intcode"gt1lt/DATAgt ltDATA ref"business.contac
  t-info.telecom.telephone. loccode"gt248lt/DATAgt
  ltDATA ref"business.contact-info.telecom.telephon
  e. number"gt3926753lt/DATAgtlt/DATA-GROUPgtlt/ENTITYgt

42
The ACCESS Element
P3P Policy syntax

• Indicates the ability of individuals to access
  their data
• ltnonident/gt
• ltall/gt
• ltcontact-and-other/gt
• ltident-contact/gt
• ltother-ident/gt
• ltnone/gt
• ExampleltACCESSgtltnonident/gtlt/ACCESSgt

43
The DISPUTES Element
P3P Policy syntax

• Describes a dispute resolution procedure
• may be followed for disputes about a services
  privacy practices
• Part of a ltDISPUTES-GROUPgt
• allows multiple dispute resolution procedures to
  be listed

• Attributes
• resolution-type
• customer service
• independent organization
• court
• applicable law
• service
• short-description (optional)
• Verification (optional)
• Sub-Elements
• ltIMAGEgt (optional)
• ltLONG-DESCRIPTIONgt (optional)
• ltREMEDIESgt (optional)

44
The REMEDIES element
P3P Policy syntax

• Sub element of DISPUTES element
• Specifies possible remedies in case a policy
  breach occurs
• ltcorrect/gt, ltmoney/gt, ltlaw/gt
• Example of DISPUTES and REMEDIES
  ltDISPUTES-GROUPgt ltDISPUTES resolution-type"la
  w"service"http//www.ftc.gov/bcp/conline/edcams/
  kidzprivacy/" short-description"Children's
  Online Privacy Protection Act of 1998, and
  Federal Trade Commission Rule"gt
  ltREMEDIESgtltlaw/gtlt/REMEDIESgt lt/DISPUTESgtlt/DISPUT
  ES-GROUPgt

45
The STATEMENT element
P3P Policy syntax

• Data practices applied to data elements
• mostly serves as a grouping mechanism
• Contains the following sub-elements
• ltCONSEQUENCEgt (optional)
• ltNON-IDENTIFIABLEgt(optional)
• ltPURPOSEgt
• ltRECIPIENTgt
• ltRETENTIONgt
• ltDATA-GROUPgt

46
The CONSEQUENCE element
P3P Policy syntax

• Consequences that can be shown to a human user to
  explain why the suggested practice may be
  valuable in a particular instance, even if the
  user would not normally allow the practice
• Example
• ltCONSEQUENCEgtWe offer a 10 discount to all
  individuals who join our Cool Deals Club and
  allow us to send them information about cool
  deals that they might be interested
  in.lt/CONSEQUENCEgt

47
The NON-IDENTIFIABLE element
P3P Policy syntax

• Can optionally be used to declare that no data or
  no identifiable data is collected
• non-identifiable there is no reasonable way to
  attach collected data to identity of a natural
  person, even with assistance from a third-party
• Stronger requirements than non-identified
• Must have a human readable explanation how this
  is done at the discuri
• Other STATEMENT elements are optinal when
  NON-IDENTIFIABLE is present
• ltNON-IDENTIFIABLE/gt

48
The PURPOSE element
P3P Policy syntax

• Purposes of data collection, or uses of data
• ltcurrent/gt
• ltadmin/gt
• ltdevelop/gt
• lttailoring/gt
• ltpseudo-analysis/gt
• ltpseudo-decision/gt
• ltindividual-analysis/gt
• ltindividual-decision/gt
• ltcontact/gt
• lthistorical/gt
• lttelemarketing/gt
• ltother-purpose/gt

• Optional attribute
• required
• always (default)
• opt-in
• opt-out
• Example
• ltPURPOSEgt ltcurrent/gtltadmin/gt ltdevelop
  required"opt-out"/gtlt/PURPOSEgt

49
Customization purposes
P3P Policy syntax
50
The RECIPIENT element
P3P Policy syntax

• Recipients of the collected data
• ltoursgt
• ltdeliverygt
• ltsamegt
• ltother-recipientgt
• ltunrelatedgt
• ltpublicgt
• Optional attribute
• required
• always (default)
• opt-in
• opt-out
• Optional sub-element
• ltrecipient-descriptiongt

• Example
• ltRECIPIENTgt ltours/gt ltsame required
  "opt-out"/gt ltdeliverygt ltrecipient-descriptiongt
  FedEx lt/recipient-descriptiongt
  lt/deliverygtlt/RECIPIENTgt

51
The RETENTION element
P3P Policy syntax

• Indicates the kind or retention policy that
  applies to the referenced data
• ltno-retention/gt
• ltstated-purpose/gt
• ltlegal-requirement/gt
• ltbusiness-practices/gt
• ltindefinitely/gt
• Example
• ltRETENTIONgtltindefinitely/gtlt/RETENTIONgt

Requires publishing of destruction timetable
linked from human-readable privacy policy
52
The DATA element
P3P Policy syntax

• Describes the data to be transferred or inferred
• Contained in a DATA-GROUP
• Attributes
• ref
• optional (optional, default is no, not
  optionalrequired)
• Sub-Elements
• ltCATEGORIESgt
• Example
• ltDATA-GROUPgt ltDATA ref"dynamic.miscdata"gt
  ltCATEGORIESgt ltpreference/gtltpolitical/gt
  lt/CATEGORIESgt lt/DATAgt ltDATA
  ref"user.home-info" optional"yes"/gt
  lt/DATA-GROUPgt

53
The CATEGORIES element
P3P Policy syntax
Provides hints to user agents as to the intended
uses of the data

• Physical contact information
• Online contact information
• Unique identifiers
• Purchase information
• Financial information
• Computer information
• Navigation and click-stream data
• Interactive data

• Demographic and socio-economic data
• Content
• State management mechanisms
• Political information
• Health information
• Preference data
• Government-issued identifiers
• Location information
• other

54
Base Data Schema
P3P Policy syntax

• User data user
• name, bdate, cert, gender, employer, department,
  jobtitle, home-info, business-info
• Third party data thirdparty
• Same as user
• Business data business
• name, department, cert, contact-info
• Dynamically generated - Dynamic
• clickstream, http, clientevents, cookies,
  miscdata, searchtext, interactionrecord

55
dynamic.miscdata
P3P Policy syntax

• Used to represent data described only by category
  (without any other specific data element name)
• Must list applicable categories
• Example
• ltDATA ref "dynamic.miscdata" gt ltCATEGORIESgt
  ltonline/gt lt/CATEGORIESgtlt/DATAgt

56
Custom data schemas
P3P Policy syntax

• You can define your own data elements
• Not required you can always use categories
• May be useful to make specific disclosures,
  interface with back-end databases, etc.
• Use the ltDATASCHEMAgt element
• Embedded in a policy file or in a stand-alone XML
  file

57
Extension mechanism
P3P Policy syntax

• ltEXTENSIONgt describes extension to P3P syntax
• optional attribute indicates whether the
  extension is mandatory or optional (default is
  optional"yes")
• Optional extensions may be safely ignored by user
  agents that dont understand them
• Only useful if user agents or other P3P tools
  know what to do with them
• Example (IBM GROUP-INFO extension used to add
  name attribute to STATEMENT elements)
• ltSTATEMENTgt ltEXTENSION optional"yes"gt
  ltGROUP-INFO xmlns "http//www.software.ibm.c
  om/P3P/editor/extension-1.0.html"
  name"Site management"/gt lt/EXTENSIONgt . . .
  lt/STATEMENTgt

58
Compact policy syntax
P3P Policy syntax

• Part of P3P Header
• P3P CP"NON NID DSP NAV CUR"
• Represents subset of P3P vocabulary
• ACCESS (NOI ALL CAO IDC OTI NON)
• CATEGORIES (PHY ONL UNI PUR ... OTC)
• DISPUTES (DSP)
• NON-IDENTIFIABLE (NID)
• PURPOSE (CUR ADM DEV CUS ... OTP) aio
• RECIPIENT (OUR DEL SAM UNR PUB OTR) aio
• REMEDIES (COR MON LAW)
• RETENTION (NOR STP LEG BUS IND)
• TEST (TST)

59
Policy reference files (PRF)
P3P Policy reference files

• Allows web sites to indicate which policy applies
  to each resource (URL or cookie)
• Every resource (HTML page, image, sound, form
  action URL, etc.) can have its own policy
• User agents can cache PRFs (as long as permitted
  by EXPIRY) so they dont have to fetch a new PRF
  every time a user clicks

60
PRF elements
P3P Policy reference files

• ltEXPIRYgt
• Determines how long PRF is valid default is 24
  hours
• ltPOLICY-REFgt
• Provides URL of policy in about attribute
• ltINCLUDEgt, ltEXCLUDEgt
• URL prefixes (local) to which policy
  applies/doesnt apply
• ltCOOKIE-INCLUDEgt, ltCOOKIE-EXCLUDEgt
• Associates / disassociates cookies with policy
  if you want a policy to apply to a cookie, you
  must use ltCOOKIE-INCLUDEgt!
• ltMETHODgt
• HTTP methods to which policy applies
• ltHINTgt
• Provides URLs of PRFs for third-party content

61
PRF example
P3P Policy reference files
ltMETA xmlns"http//www.w3.org/2002/01/P3Pv1"
xmllang"en"gt ltPOLICY-REFERENCESgt ltEXPIRY
max-age"172800"/gt ltPOLICY-REF
about"http//www.example.com/privacy.xmlpolicy1"
gt ltINCLUDEgt/lt/INCLUDEgt
ltINCLUDEgt/news/lt/INCLUDEgt
ltEXCLUDEgt/news/top/lt/EXCLUDEgt lt/POLICY-REFgt
ltPOLICY-REF about"http//www.example.net/pp.xm
lpolicy2"gt ltINCLUDEgt/news/top/lt/INCLUDEgt
lt/POLICY-REFgt ltPOLICY-REF
about"/P3P/policies.xmlpolicy3"gt
ltINCLUDEgt/photos/lt/INCLUDEgt
ltINCLUDEgt/ads/lt/INCLUDEgt
ltCOOKIE-INCLUDE/gt lt/POLICY-REFgt ltHINT
scope"http//www.example.org"
path"/mypolicy/p3.xml"/gt lt/POLICY-REFERENCESgt lt
/METAgt
62
Policy updates
P3P Enabling your web site overview and options

• Changing your P3P policy is difficult, but
  possible
• New policy applies only to new data (old policy
  applies to old data unless you have informed
  consent to apply new policy)
• Technically you can indicate exact moment when
  old policy will cease to apply and new policy
  will apply
• But, generally its easiest to have a policy
  phase-in period where your practices are
  consistent with both policies

63
Organizing a Research Paper
64
Organizing a research paper
Research and Communication Skills

• Decide up front what the point of your paper is
  and stay focused as you write
• Once you have decided on the main point, pick a
  title
• Start with an outline
• Use multiple levels of headings (usually 2 or 3)
• Dont ramble!

65
Typical paper organization
Research and Communication Skills

• Abstract
• Short summary of paper
• Introduction
• Motivation (why this work is interesting/important
  , not your personal motivation)
• Background and related work
• Sometimes part of introduction, sometimes two
  sections
• Methods
• What you did
• In a systems paper you may have system design and
  evaluation sections instead
• Results
• What you found out
• Discussion
• Sometimes called Conclusion
• May include conclusions, future work, discussion
  of implications,etc.
• References
• Appendix
• Stuff not essential to understanding the paper,
  but useful, especially to those trying to
  reproduce your results - data tables, proofs,
  survey forms, etc.

66
Road map
Research and Communication Skills

• Papers longer than a few pages should have a
  road map so readers know where you are going
• Road map usually comes at the end of the
  introduction
• Tell them what you are going to say, then say it,
  (and then tell them what you said)
• Examples
• In the next section I introduce X and discuss
  related work. In Section 3 I describe my research
  methodology. In Section 4 I present results. In
  Section 5 I present conclusions and possible
  directions for future work.
• Waldman et al, 2001 This article presents an
  architecture for robust Web publishing systems.
  We describe nine design goals for such systems,
  review several existing systems, and take an
  in-depth look at Publius, a system that meets
  these design goals.

67
Use topic sentences
Research and Communication Skills

• (Almost) every paragraph should have a topic
  sentence
• Usually the first sentence
• Sometimes the last sentence
• Topic sentence gives the main point of the
  paragraph
• First paragraph of each section and subsection
  should give the main point of that section
• Examples from Waldman et al, 2001
• In this section we attempt to abstract the
  particular implementation details and describe
  the underlying components and architecture of a
  censorship-resistant system.
• Anonymous publications have been used to help
  bring about change throughout history.

68
Avoid unsubstantiated claims
Research and Communication Skills

• Provide evidence for every claim you make
• Related work
• Results of your own experiments
• Conclusions should not come as a surprise
• Analysis of related work, experimental results,
  etc. should support your conclusions
• Conclusions should summarize, highlight, show
  relationships, raise questions for future work
• Dont introduce new ideas in discussion or
  conclusion section (other than ideas for related
  work)
• Dont reach conclusions not supported by the rest
  of your paper

69
Homework 4 Discussion

• http//lorrie.cranor.org/courses/fa05/hw4.html
• Privacy software reviews
• Why do sites use web bugs?

70
Homework 5 Discussion

• http//lorrie.cranor.org/courses/fa05/hw5.html
• Similarities and differences of P3P user agents
• What did you like or dislike about them?
• Experience creating bank P3P policies