Intl. Conf. on Computers, Privacy & Data Protection

P i b D iPrivacy by Design

Marc LangheinrichUniversity of Lugano (USI)

Switzerland

NON PRIVACY BY NON DESIGNExample 1

NON PRIVACY BY NON DESIGN

2006

20 cards20 cards

no encryption

C dh ld ‘ NCardholder‘s NameCard Number

Expiration DateExpiration Date

2008

C dh ld ‘ NCardholder‘s NameCard Number

Expiration DateExpiration Date

*MacBook Air not included

2008

Non Privacy By Non Designy y g

NON PRIVACY BY BAD DESIGNExample 2

NON PRIVACY BY BAD DESIGN

P<D<<LANGHEINRICH<<MARC<<<<<<<<<<<<<<<<<<<<<123456789?D<<710123?M070101?<<<<<<<<<<<<<<<?123456789?D<<710123?M070101?<<<<<<<<<<<<<<<?

Protection from Forgery!!Protection from Forgery!!

Digital Signature

„ ...cloned and manipulated... “

MustermannChristian

?Christian0000000000000

?Proof of Genuine Passport ?

Non Privacy By Bad Designy y g

PRIVACY BY DESIGN?Example 3

PRIVACY BY DESIGN?

Smart Fridgeg

Smart Stove

Receiptless Returns

Fast Checkout

WhiggModel #2342

Material: PolyesterTiger Tanga

Maker: Aldi (Suisse)Last washed: 5 days ago

ViagraLabo

rato

ries

Maker: PfitzerSize: Maxi (60 pills)

2006

Ari

Juel

s, R

SA

D-M

an”

Art

wor

k (c

) O

rigi

nal “

RFID

Working Hypothesis

People don‘t wantPeople don t want privacy toolsprivacy tools

People want toPeople want to get things done!get things done!The more secure, private, safe, the better

Getting ThingsGetting Things Done?Done?

Vision

Hands Free PrivacyHands Free Privacy

The more secure, private, safe, the better

Example: The Shamir TagExample: The Shamir Tag

Langheinrich, Marti: Practical Minimalist Cryptography for RFID Privacy. IEEE Systems Journal, Vol. 1, No. 2, 2007

Example: The Shamir TagExample: The Shamir Tag

• Unsolicited read outs take long time• Unsolicited read-outs take long time–Difficult (but not impossible) to track

or identify

• Instant Identification for known tags• Instant Identification for known tags–Owner uses tags without restrictions

Langheinrich, Marti: Practical Minimalist Cryptography for RFID Privacy. IEEE Systems Journal, Vol. 1, No. 2, 2007

Shamir Tags IllustratedShamir Tags Illustrated

Original d bOriginalRFID-Tag:

RFID-Tag contains encrypted ID + Key, but cut in many small pieces. All pieces are needed to decrypt Tag ID.

Shamir Tags IllustratedShamir Tags Illustrated

Original d bOriginalRFID-Tag:

RFID-Tag contains encrypted ID + Key, but cut in many small pieces. All pieces are needed to decrypt Tag ID.

UnknownReader sees:

wait wait wait

Only few shares disclosed A few more shares disclosed Still not enough shares…

titime

Shamir Tags IllustratedShamir Tags Illustrated

Original d bOriginalRFID-Tag:

RFID-Tag contains encrypted ID + Key, but cut in many small pieces. All pieces are needed to decrypt Tag ID.

UnknownReader sees:

wait wait wait

Owner‘s

Only few shares disclosed A few more shares disclosed Still not enough shares…

+ =Owner‘sReader sees:

Owner checks for Instant IdentificationOnly few shares disclosed Owner checks forknown (cached) tag

y

Consumers receive basicprotection for all tagged goods

Additional security mechanism ycan be layered above Shamir Tags

Summary

Privacy by DesignPrivacy by Design

• Difficult to do even for technology expertsDifficult to do even for technology experts– Industrial (RFID Credit Cards)

Government (ePassport)– Government (ePassport)

• Difficult if wrong user model– People want to get things done

– Privacy, security often gets in the way

• We need usable security and privacy– Sometimes less security may mean more privacy