Anonymity - Background

R. Newman

Early (pre-computer) uses for social reasons (ability to act more freely, have work accepted without prejudice, etc.)

Traffic analysis an issue prior to computers (e.g., Bodyguard of Lies)

Computer TAP solvable with cryptography With public-key cryptography, theoretical

possibility for anonymity and pseudonymity

Anonymity - Beginnings

Topics

Defining anonymity Defining privacy Need for anonymity Threats to anonymity and privacy Mechanisms to provide anonymity Applications of anonymity technology

Privacy/Anonymity Threats

Available surveillance technology Identification technology Increasing use of databases Data mining Identity theft Increasing requirements for I&A Increasing governmental desire for surveillance

Surveillance Facts

1.5 million CCTV cameras installed in UK post 911 – Londoner on camera ~300 times a day http://epic.org/privacy/surveillance/

Face recognition software used in Tampa for Superbowl

5000 public surveillance cameras known in DC Home and work zipcodes give identity in 5% of

cases in US http://33bits.org/tag/anonymity/

Homework

Count number of video cameras you encounter all day for one day.

Record locations, submit when Canvas up. Tally total, share total with class Friday.

Data Reidentification

Even ”scrubbed” data can be re-identified Characteristics within the data (e.g., word

usage in documents) Intersection attacks on k-anonymized database

set releases Use of known outside data in combination with

released data Data mining – higher dimensional space gives

greater specificity!

Exercise

What are legitmate limitations on anonymity? Write down 1-2 of these Share with neighbor Share with class

Limitations on Anonymity

Accountability Legal/criminal issues Social expectations Competing need for trust

Others?

Forms of Anonymity

Traffic Analysis Prevention Sender, Recipient, Message Anonymity Voter Anonymity Pseudonymity Revokable anonymity Data anonymity

Topics

Defining anonymity Need for anonymity Defining privacy Threats to anonymity and privacy Mechanisms to provide anonymity Applications of anonymity technology

Anonymity Mechanisms

Cryptography Steganography Traffic Analysis Prevention (TAP) Mixes, crowds Data sanitization/scrubbing k-anonymity