Feb 23, 2016
Privacy TechnologyAnalysis and Mechanisms
David Chaum
Privacy is fundamentallyimportant!!!
• Is essential for democracy– Needed for participation without fear of retribution
• Is a fundamental human right
OUTLINE
• Analysis – Policy– Economic
• Solution Mechanisms– Legal– Technological
• “Privacy Technology”
Policy Analysis
The actors and macro considerations
Hierarchy of IT Needs of Humans
• Self-Worth—relation to: artificial intelligence, etc.
• Privacy—identity, credential & role protection
• Interaction—communication, exploration, commerce
• Security—uptime, robustness, no hacking
• Processing—storage, interface, crunching
Maslow’s Hierarchy of Needs
Policy Issues
Economic Analysis
These days, everybody’s an economist!
Monetizing privacy
• Various schemes proposed (even 20+ years ago)
1. Consumers pay for privacy protection services
2. Consumers are paid for use of their privacy-related data
3. A brokerage of privacy related data
Imbalance in desire for privacy/data
• Individuals discount present value of privacy protection in transactions– Explains anomalous behavior of consumers when
confronted with cost or inconvenience– Practices and potential dangers unknown
• Organizations value personal data– Overestimate future potential of data– Discount exposure to organization– An organization not too concerned about dangers posed
to consumers that it is not accountable for
Imbalance in size/power of entities
• Organizations have lots of leverage• Their are few sources of mass products
and services• Consumers don’t have much choice for
many products or services• High relative cost of change of practices
for consumers
Legal mechanisms
Powerful but don’t work well directly
Legal mechanisms—evolution
1. Originally based on codifying legitimate expectation of privacy
2. People should be able to review and amend data
3. No erosion of privacy due to technology4. Best privacy protection practical
Legal mechanisms—capabilities
• Accountability after the fact is ineffective– Hardly able to address
• Covert/clandestine abuse• Abuse of public or leaked data• Corporate shield• Undoing damage done to people
• Can cause creation and use of infrastructure
Technological Mechanisms
The directly-effective mechanism
Locus of privacy-related control—The critical architectural choice
infomediary
Organization x
Locus of control—Three choices:
1. At organizations• Weak benefit/effect for consumers• Clandestine abuse, leaks, reversibility…• Mollify/diffuse the issue – prevent effective solutions
2. At an intermediary• Create infrastructure with single point of failure • Full cost but little true benefit• Dangerous concentration
3. At the individual• Privacy technology – the only good solution
Old paradigm—assumptions/model proven false!• Believed to be a zero-sum game,
privacy v. security• ID believed needed for security against
abuse by individuals• ID believed only way to organize data
Old Paradigm
J. Doe3834343
J. Doe3834343
J. Doe3834343
J. Doe3834343
J. Doe3834343
raw data raw data
New paradigm
• Individuals provide organizations with minimum sufficient information and proof of its correctness
Privacy Technology
Win-Win break of the believed tradeoff
New Paradigm
Feasibility of a comprehensive solution set has been proven
• Payments—eCash payments deployed by major banks on 4 continents
• Communication—Mix nets, onion routing, etc. have been widely deployed
• Credentials—mechanisms implemented on cards and by IBM
Benefits to organizations (micro)
• Reduced exposure/liability• Better data
– Cleaner because less deception and garbage– More willingness to provide data because of
protections• All organizations get the data; level playing
field• Better public image (?) – probably wrong!
Not easy to get there from here
• Requires lots of users (hard to be anonymous alone!)
• Difficult to get the system “primed”• Consumers don’t want to pay costs• Organizations tend to resist change
Really an “infrastructure issue”
• Pseudonymity / Anonymity only “in numbers” (as mentioned)
• Communication infrastructure can nullify protections
• Way to share data pseudonymously is infrastructure
CONCLUSION
A “Privacy Technology” infrastructure is the way to go and would be hugely beneficial
Kinds of Privacy for Payments
Governmentpayments, e.g.
transfer-order systems
pre-paidphone cards bank notes
& coins
eCash™
stored-valuecards
credit cards onthe Internet
No privacy False privacy
Consumer-controlled
privacy
Organization-controlled privacy
privacy / consumer-control
tech
nolo
gy /
time
Protectiononly frommerchantAdvertiseconsumer
privacy
Buy/reload card withoutidentification
Consumer Payments Market Space
high value
irregularpayments
scheduledpayments
$10low value
Electronic Cash
• You can buy a digital “bearer” instrument from a bank with funds in your account
• You can pay by giving the instrument to the payee, who deposits to an account
zoom in on eCash blinding
Privacy and Control over Payments
• Nobody can learn without your cooperation who you pay, how much you pay, or when
• You can always prove who received any payment, for how much, and when
• Payments can only be made by you and they cannot be stopped by others
Credential Mechanisms
• You deal with each organization under a distinct “digital pseudonym”—a public key whose corresponding private key only you know
• You obtain a “credential” as a digital signature formed on one of your digital pseudonyms
• You answer the queries you choose to by proving you have sufficient credentials
Wallet with Observer
• A tamper-resistant chip, issued by a trusted authority, is carried by the individual
• But the chip can only talk to the outside world through the person’s PC/PDA
• The two devices perform a multiparty computation and thus speak to the outside world with a common voice
How untraceable-sending works
message 1
message 2
message 3
message 4
The “mix” sever decrypts and re-orders inputs
Mix network
Prevents tracing messages back
message 2?
Cascade of three Mixes
Server 1 Server 2 Server 3
PK1 PK2PK3
Encryption of messagePK1 PK2
PK3
message
Ciphertext = EPK1[EPK2[EPK3[message]]]
Processing the messages
Server 1 Server 2 Server 3
m1
m2
m3
m2
m3
m1
decryptand
permutem2
m1
m3
decryptand
permute
decryptand
permutem2
m3
m1
Tracing prevented by any mix
Server 1 Server 2 Server 3
m3?
IAOThe Information Awareness Office (IAO) develops and
demonstrates information technologies and systems to counter asymmetric threats by achieving total information awareness useful for preemption, national security warning and national security decision-making. John Poindexter, national security adviser to former President Reagan, is the director of the new agency. He was a controversial figure both for his role in the Iran-contra scandals and for his efforts to assert military influence over commercial computer security technologies. NSDD 145 & Data Mining.