Orfeas Stefanos Thyfronitis Litos
olitos@corelab.ntua.gr
- Trust over correspondence of physical identity and public key
- Single transitivity step
- File sharing decentralized platform with spam protection
- No explicit trust definitions
- PGP Pathfinder finds transitive closure: http://pgp.cs.uu.nl
- Nodes and files have unique keys
- File key requests directed to node with closest node key
- Popular files replicated, old files forgotten in LRU fashion
- Certification Authorities vouch for website authenticity
- Requires trust to central third parties
- Users' undirected graph created out of their interactions
- A successful interaction between A and B leads to
increased weight of the edge (A, B) and the opposite
- Need for centralized storage and graph secrecy
- Can reduce frauds in online marketplaces
Trust
Reciprocity
Reputation
- Users can make binary choices which are recorded
- Trust is the average of the ratings available to the user
- Future user behaviour predicted with Beta distribution
- Global ratings stored by each user's neighbours
- Hierarchical trust system: Nodes in tree structure,
parents more trustworthy than children
- Suitable for collaborating hardware and software with
variable specifications and no central coordinator
- Trust from A to B factors:
A's Propensity and B's Ability, Benevolence and Integrity
- BitTorrent peer trust calculation using maximum flows
- Explicitly assigned trust percentages pertaining to
responsible use of PGP tools, web of trust is created
- Decentralized marketplace
- Single review per purchase - global rankings
- Fees to discourage fraud by rational players
- Global rankings generated per transaction
- Decentralized rating system for IoT appliances
- Requires trust value assignment per incoming message
- 4C's: Content, Communication, Computation and Counteraction
- The weight of the edge (Alice, Bob) is the time Alice and
Bob have spent together
- Actual borrowing between unknown parties predicted
very accurately through maximum flow calculation
Trust
Propensity
Risk
Propensity
Subjective
Trust
Goodwill Trust
Competence Trust
Perceived
Risk
Relational Risk
Performance Risk
-1
-1
Behavioural
Trust
Risk
Taking
A
B
C
2
4
1) Initially
2) Trust path found. C buys a product of value 1 from D
3) Finally
A
B
C
1
3
Example:
D
D
1
A, B are even, D gained 1 and C lost 1
Das, T. K., Teng, B. S.: The risk-based view of trust: A conceptual framework. Journal of Business and Psychology, 19(1), 85-116 (2004)
Fugger R.: Money as IOUs in Social Trust Networks & A Proposal for a Decentralized Currency Network Protocol (2004)
Schwartz D., Youngs N., Britto, A.: The Ripple protocol consensus algorithm. Ripple Labs Inc White Paper, 5 (2014)
Mazieres, D.: The stellar consensus protocol: A federated model for internet-level consensus. Stellar Development Foundation (2015)
DeFigueiredo D. D. B., Barr E. T.: TrustDavis: A Non-Exploitable Online Reputation System. CEC, Vol. 5, pp. 274-283 (2005)
Jøsang A., Ismail R., Boyd C.: A Survey of Trust and Reputation Systems for Online Service Provision. Decision Support Systems, 43(2), pp. 618-644 (2007)