Proof-of-Personhood How to resist Sibyl attacks DEDIS, EPFL Linus - - PowerPoint PPT Presentation

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Proof-of-Personhood How to resist Sibyl attacks DEDIS, EPFL Linus - - PowerPoint PPT Presentation

Nov 11, 2023 239 likes •470 views

Proof-of-Personhood How to resist Sibyl attacks DEDIS, EPFL Linus Gasser, Philipp Jovanovic, Eleftherios Kokoris, Frederic Pont, Bryan Ford 1 The Sybil Identity Problem Internet has no protection from malicious users cheaply creating a few

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Proof-of-Personhood

How to resist Sibyl attacks

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DEDIS, EPFL Linus Gasser, Philipp Jovanovic, Eleftherios Kokoris, Frederic Pont, Bryan Ford

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Internet has no protection from malicious users cheaply creating a few (or many) fake accounts

  • Online ballot stuffing, fake upvotes/reviews
  • Sock puppetry, bot armies pushing fake news
  • Whack-a-mole: “banned” trolls just resurface

Fundamental unsolved decentralization problem

  • John Douceur, “The Sybil Attack” [IPTPS ‘01]”
  • Bitcoin PoW is another disastrous failed attempt

The Sybil Identity Problem

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Major approaches proposed so far:

  • “Real names” based on verified identities
  • Biometric collection in central database
  • Proof-of-Investment: CAPTCHA, PoW, PoS, …
  • Graph analysis on trust networks
  • Pseudonym parties

Mapping the Known Solution Space

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Trusted third-party verifies government-issued ID

  • Blue checkmarks, banking KYC checks, ...

Downsides:

  • Privacy-invasive, excludes poor/undocumented
  • Cumbersome, expensive verification process
  • Fake IDs relatively easy, cheap to acquire
  • Vulnerable to 1 compromised/coerced verifier

“Real names” and verified identities

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Collect fingerprints, iris, etc., record in database

  • Appeals: efficiency, automation, security(?)
  • Large-scale trials by India, United Nations

Downsides:

  • Even more privacy-invasive, surveillance risks
  • False positives & negatives create big problems
  • One hacked scanner could still register many fake “people” with unique

biometric fingerprints

Biometric collection & verification

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Rate-limit Sybil attacks via artificial barrier-to-entry

  • CAPTCHAs: waste time proving you’re human
  • PoWork: prove you wasted compute energy
  • PoStake: prove you have money to invest

Downsides:

  • Undemocratic: not “one-person-one-vote”
  • More money, more voice: “rich get richer”

Proof-of-Investment

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Classic P2P idea in SybilLimit, SumUp, etc. Assumes nodes are cheap but edges are expensive to a Sybil attacker. Downsides:

  • Secure & usable “trust networks” don’t exist

○ Facebook/LinkedIn/etc: many friend promiscuously

  • Only weak defense against massive cheating

○ Easy for many people, or everyone, to cheat a little

Graph analysis on trust networks

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Build anonymous one-per-person tokens

  • Physical security: real person has one body, can be in
  • nly one place at a time
  • Synchronized events similar to, but simpler than,

in-person voter registration or PGP key signing

  • No ID checking, no biometrics, no trust network

Downsides:

  • Requires some organization in the physical world
  • Those who want one must show up, periodically

Pseudonym Parties

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Objective: Number of tokens per person = 1 How: Organizing a party in which people are verified, but not identified

Proof of Personhood

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Pseudonym-party - Setup

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Organizers

Anytrust

Attendees

Anonymity- group

Room

BC01

Configuration Name, Purpose, Place, Time

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Step 1: Pseudonym-party - Configuration

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Organizers

Each organizer signs the configuration

Collective Signature Blockchain

Configuration and Signature stored on

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Step 2: Attendee Configuration

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https://applivery.com/popcoin Pop-party #11 4th of September 2018 BC410

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Step 3: Start of Party

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Be sure to:

  • Install the latest

version from https://applivery.com/ popcoin

  • Scan the QRCode of

the party

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Step 4: Barrier Point - Exit and Scan

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You’re allowed to exit the party. Be sure to have your public key scanned by all the organizers!

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+ =

Step 5a: Creation of Party Transcript

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Organizers

Organizers reach consensus

Collective Signature Configuration Public Keys Party Transcript

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Step 5b: Storage of Party Transcript

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Is sent to

Party Transcript Blockchain Smart Contract Anonymous Accounts

Calls Creates

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+ =

Step 5c: Tokenization of Attendee’s Keypair

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Party transcript Keypair PoP-token

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Usage of PoP-Coins and PoP-Tokens

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Attendee

Transfers Coins

Economic

Other Attendees Services

Social

Sybil-resistant Twitter Spam-protected Communication Voting Deliberation

Democratic

Signs Anonymously

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Details of Anonymous Signatures

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Attendee

Request Each service trusts the Party Transcript

Services

Each service holds a list of tags: Message + Context Signature + Tag ...

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Log

  • Date: 4th of September 2018, 1:30pm - Place: BC410 in EPFL, Lausanne, CH
  • Organizers: Linus, Kelong, and Sacha
  • Total Attendees (including organizers):
  • Observer:
  • Nodes: conode.dedis.ch:7770, conode.dedis.ch:7772,

conode.gasser.blue:7770

  • Chocolate/fruits for everybody!

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Next steps

  • Don’t lose tokens!
  • Have a minimal mock-up of the following functionality:

○ Creating and answering Questionnaires ○ PoP-twitter where sending costs money and reading gets you money ○ Get coins from a token to get a certain amount of coins and being able to exchange coins

  • Having organizer functionality in iOS version

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