Open Reputation Systems

Overview

OASIS ORMS (Open Reputation Management Systems) introductionUse cases, requirements and modelENISA Paper on Security Issues in Reputation SystemsSome thoughts on reputation standardisation

OASIS - ORMSGoal: Definition of a portable reputation formatProcess:

Use-case definition for reputation managementReference/standard model

• Flexible reputation data model• Framework and protocol/s for exchanging and

porting reputation data (SAML/IDP based)• Evaluation algorithms for mapping reputation to

risk / risk levels• Support for privacy, multiple identities, identity

resolution

Use-cases 1

Seller reputation

Peer-to-peer

Key management

Anti-spam/IP reputation

Use-cases 2

Content filtering

Avatar Reputation

Social Network Peer Reputation

Unified Communications (IM, SPIT/SPIM etc…)

Digital Identity

Summary of actual past behavior, by service provider

Real identityBackground check

against external data

Peer reviews

portable

specific

Identity Verification, Identity Proofing

= Strong Identity

Trust in specific attribute or future behavior?

Requirements

Enroll & Proof Users

Define Policy

Issue & Manage User Rights

Enforce Access Control

Monitor, Audit, Report

Reputation

Reputation

Reputation

Reputation

Reputation (in Policy)

Reputation

Modelling Reputation in a Standard -Thoughts

Reputation is an aggregation of opinions about an assertion

Assertion – Bob is a good laptop

seller

Assertion – Bob is a good laptop

seller

Assertion – Bob is a bad husband

Assertion – Bob is a bad husband

Score 0.2 – i.e. He is not a good laptop seller

Score 1 – i.e. He IS a bad husband

The anatomy of reputation – personal view

Assertion – Bob is a good laptop seller

Assertion – Bob is a good laptop seller

Reputation ThoughtsIf reputation is an aggregated opinion about an assertion – why not integrate with SAML and IDP infrastructure?

Reputation votes should be separated from the algorithm used to compute it

Mean score2nd order reputationReputation Context

=> Same vote set can be interpreted differently

Reputation Thoughts

Model must allow for so-called 2nd order reputations (scores which take into account the reputation of the voter)

Rating context should be taken into account – time/date, authentication method/token etc...

Security of Reputation Systems

ENISA paper – a security analysis of reputation systemshttp://enisarep.notlong.com

Typical security vulnerabilities need to be addressed:

Collusion–voters agree to target a victimDenial of reputation – campaigns against an individualWhitewashing (cancelling a bad reputation)Sybil attacks (creating multiple identities to vote – e.g. Ebay 1 cent items voted on by seller)

Take home messages

ORMS is working towards a global portable reputation standards.Reputation is just another kind of assertionImportance of including features like authentication, privacy, 2nd order reputationImportance of addressing security issues.

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