CS-438Decentralized Systems Engineering

Week 11

Anonymous Communication

Motivations- political dissidents (in

authoritarian regime)- isolate work & personal- protect freedoms of speech, association- voting : ballots are anonymous

- hide criminal activity from law enforcement

Approaches :

-

"Natural" anonymity :

"feel"

of anonymity

IIP addresses, phone numbers . .

..

ADELE,boob

Proxies,

Virtual Private Network crew)#ftp.#.Lo*I&3ob

weakness : proxy is a centralized,trusted party

- Multi - hop relaying : MIX -nets,

Tor,(onion routing)*dice! if

(David Chuang- Dining Cryptographers CDC -nets) : into.ie?nagfonAiigg:o!!-#edoBob

Relayingapproaehes-MIX - nets ( charm) : high - latency, delay - tolerant messagesffljceemzytxnemailerr

( USENET,Email)

email On'

Bob - low trust in each Mex

do post to- traffic analysis resistance

AT 99 Usenet group - batching, delaysINSA) - low usability (non - interactive- Onion routing (Tor)

:'low - latency, interactive (web)

Swisscom swigs.com

aol.ie#:*.i*oB..:::in:::ieir....:::.!:rs0 Server analysiscorrelation Chyna! genies

④'

vantage points)

Information coding: Dining cryptographers (DC - nets)- is

O ' O -parallel instances

÷÷÷÷÷i÷÷÷÷÷÷÷:÷:÷. .in: ÷:÷:::÷÷..- Ir e)form different

groups,O see whichgroups

" work"

O O - intersection attack

servers(trustees-

"

trap " or"blame " mechanisms

'd 8 O' ( "any trust"- Mahonymous scheduling

±

'its '%:&.fi - zero -knowledge proofs verdict)oooo oooo co

- Security : want all-to -all coin sharing- ⑧ In ') - less scalableeagle twitter trustees84979 Low-latency e o

o- promise : low - latency DC -nets ?

owPNrde## - Pnifi ( kudovic Barmanet.ae/)relatqqqcow-late#e④ Clients thighAnonymity set latency