Proof-of-Personhood : Redemocratizing Permissionless - - PowerPoint PPT Presentation

Proof-of-Personhood: Redemocratizing Permissionless Cryptocurrencies

Maria Borge, Eleftherios Kokoris-Kogias, Philipp Jovanovic, Linus Gasser, Nicolas Gailly and Bryan Ford

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EPFL

Talk overview

• Problem
• Proof of personhood (PoP)
• PoPCoin
• Conclusions

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Problem

Control in current permissionless blockchain-based cryptocurrencies systems lies in hands of a small number of entities

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Re-centralization

Permissionless cryptocurrencies

• Enable open participation
• Provide pseudonymity
• Avoid double spending attacks
• Extend the blockchain in a secure manner

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Proof-of-Work

• Special purpose hardware
• Massive consumption of electricity
• Only entities with the resources are able to mine
• Re-centralization!

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Proof-of-Stake

• Participants use their assets to create new assets
• Rich participants have an advantage, more assets implies

faster creation of new assets

• Shareholder corporation that favors the rich

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Goal

Create a sybil attack resistant cryptocurrency that ensures fair and accessible wealth creation process

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Talk overview

• Problem
• Proof of personhood (PoP)
• PoPCoin
• Conclusions

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Proof-of-Personhood (PoP)

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Objective: Verify people, rather than identify them How: Organizing a party and generate tokens

PoP-Token PoP-Token PoP-Token

Proof-of-Personhood (PoP)

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CoSi - Scalable collective signing Cothority - Collective Authority Linkable ring signatures - Anonymity and accountability in the same context

Pseudonym party - Setup

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Conode Conode Conode

Organizers Configuration-file:

• Start, End
• Location, Use
• Expiration
• Organizers’ public

keys Cothority

Pseudonym party - Setup

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Attendees E Public keys Private keys Configuration-file:

• Start, End
• Location, Use
• Expiration
• Organizers’ public

keys

Pseudonym party

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Registration-room Party-room

Pseudonym party - Barrier Point

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Registration-room Party-room

Pseudonym party

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Registration-room Party-room

Pseudonym party - Termination / Finalization

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Conode Conode Conode

Party Transcript:

• Configuration file
• Public keys of attendees
• Hash-file of videos
• Collective signature

Private key + = Organizers Cothority PoP-Token

Usage of PoP-Tokens

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Aggregate public key of trustworthy cothorities

Linkable Ring Signature Context, M

... ... Attendee Table with tags Attendees public keys Attendees public keys ... Service

Talk overview

• Problem
• Proof of personhood (PoP)
• PoPCoin
• Conclusions

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PoPCoin

• Open membership: Proof-of-Personhood
• Fairness: Randhound
• Consensus: Byzcoin

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PoPCoin - Implementation - Setup

• 1. Set of organizers throw a pseudonym party to create

PoP-tokens

• 2. Attendees authenticate their PoP-tokens
• 3. If successfully authenticated attendee deposits a public

key, to identify as a minter

• 4. The set of public keys form a minting-pool

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PoPCoin - Implementation - Minting

• 1. Minters part of the minting-pool are eligible to create new

blocks

• 2. Last N miners run RandHound, to select the next minter

allowed to create next block

• 3. The process repeats every M minutes, if minter fails a new
• ne is selected

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PoPCoin - Overview

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PoPCoin - Deployment

Local cryptocurrency

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Challenges

We propose a cryptocurrency that builds on:

• Proof-of-Personhood
• Randhound
• Byzcoin

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Related Work

We propose a cryptocurrency that builds on:

• Proof-of-Personhood
• Randhound
• Byzcoin

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Thank you!

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Questions?

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