FairCASH Best Path ID

Master Thesis PresentationDimitar Vladimirov Dimitrov: 

Master Thesis Presentation Dimitar Vladimirov Dimitrov Conception and Implementation of Services, Protocols and Algorithms for the fairCASH System Research Group for Technical Computer Science Prof. Dr. rer. nat. Manfred Schimmler Supervisor: Dipl.-Ing. (TU) Heinz Kreft

Introduction : 

Introduction Paper money and cash – basics Digital cash – Means of payment in the pure form of Information 000100110001001 E-tokens – value carriers, special encrypted packets containing data Digital transactions and security

Money Evolution : 

Money Evolution Value carriers evolve with the technical progress People begin to trust less material means of value Money time-line

“Success Factors” that Motivated Our Development: 

“Success Factors” that Motivated Our Development

Electronic Money Systems categorization: 

Electronic Money Systems categorization

Interesting Features for our Digital Cash System - fairCASH: 

Interesting Features for our Digital Cash System - fairCASH A Multipurpose system (micro, mezzo, macro payments) Multi-currency support Pre-paid system Inter-operable system – Platform independence (can form cooperating and private exchange networks) Cross compatibility at the transport layer VERY IMPORTANT! - Perfect anonymity (combination of untraceability + unlinkability)

fairCASH Main Characteristics: 

fairCASH Main Characteristics E-Token based system Peer2Peer technology Total Offline (no 3-rd party involved) operation supported Online operation also supported Perfect anonymity Flexibility and cost effectiveness Multy hopping capability – e-Token circulation (picture on the next slide)

fairCASH Main Characteristics: 

fairCASH Main Characteristics Multy hopping capability – e-Token circulation

Overview of the different communication phases of fairCASH Peer-2-Peer messages and my focus: 

Overview of the different communication phases of fairCASH Peer-2-Peer messages and my focus

fairCASH e-Token - Best Path Identification Exchange Process: 

fairCASH e-Token - Best Path Identification Exchange Process The Singleton process incorporates in its intelligent core logic: Exchange Algorithm Rules that are the basis for the “Best Path Identification of a weighted e-Token based Cash P2P Exchange Cooperation Process” E-Tokens handing and optimal wallet loading and coin distribution operations Peer2Peer e-Token transport protocol

Peer2Peer Communication exchange scheme: 

Peer2Peer Communication exchange scheme

Optimum Transaction rules: 

Optimum Transaction rules Minimum overall coin exchange for the transaction Try to perform single unidirectional transactions Given the amount to be transferred give and collect as much as possible bigger pieces of coins in order not to run of coins Ask and allow overcharge/underspend as a transaction enable rescue method In a transact-impossible situation first the sending peer should attempt online connect than the receiving peer should make such an attempt

E-Token handling algorithms: 

E-Token handling algorithms Coin allocation algorithm for e-Wallet Loading Coin dispensing algorithm for money exchange and payment to the remote peer

Coin allocation algorithm: 

Coin allocation algorithm N – Amount to be allocated P – Max denomination allowed R – Restricted denomination set M[i] - array with the coin denominations and their amounts

Coin allocation algorithm results: 

Coin allocation algorithm results Amount to be loaded into the e-Wallet 100 Euro Allocations according to the algorithm:

Coin Smart-Greedy Dispensing Algorithm: 

Coin Smart-Greedy Dispensing Algorithm P – Amount to be paid (bill) R – Iteration variable for the M vector representing the least number of coins to be dispensed D – Is the allowed denomination set C- Max coin denomination i – Iteration variable index equal to the needed amount to be dispensed M – is an R-length vector of multi sets: before the i’th iteration of the while loop M[i] is the needed array with the coin denominations and their amounts

Coin Smart-Greedy Dispensing Algorithm: 

Coin Smart-Greedy Dispensing Algorithm Amount (37.56) to be paid from an e-Wallet loaded with 100 Euro Allocations according to the Smart-Greedy dispense algorithm:

Peer2Peer Communication Protocol Entities: 

Peer2Peer Communication Protocol Entities Two Communicating instances in each peer Important: each peer can send and receive e-Tokens over a standard TCP/IP network Listener (services provider) Connect initiator (services consumer) Both provider/consumer are integrated into one entity to for the truly Peering environment

Peer2Peer Communication Protocol basics: 

Peer2Peer Communication Protocol basics The protocol implements a fast hand-shake algorithm using control bits and message payloads Control bits – Even are input for the service provider instance and Odds are input for the service consumer instance Messages payload (Implements the needed logic) Connection less protocol working on the non-reliable part of the transport layer

Peer2Peer Communication Protocol Structure: 

Peer2Peer Communication Protocol Structure

Peer2Peer Communication Protocol Cooperation: 

Peer2Peer Communication Protocol Cooperation Network protocol optimal for solving our problem ‘ctrl bit’|’msg + payload’ service consumer: 10| msg=‘Reaction|Question |Affection’; service provider: 11| msg=‘Reaction|Answer|Affection’; service consumer: 20| msg=‘Reaction|Coin Payload|Affection’; WD: Watch Dog

Peer2Peer Communication & e-Token exchange demonstration: 

Peer2Peer Communication & e-Token exchange demonstration Case Study 1 – Uni-directional Offline transaction – exact bill amount match, exact payment possible PeerA pays the bill to PeerB Peer A e-Wallet state: 100 Euros Peer B e-Wallet state: 0 Euro Bill 25,27 Euros

Peer2Peer Communication & e-Token exchange demonstration: 

Peer2Peer Communication & e-Token exchange demonstration Case Study 2 – Bi-directional Offline transaction – No exact bill amount match, change for the payment returned PeerA pays the bill to PeerB PeerA e-Wallet state: 20 Euros (2 demominations of 10 Euro) PeerB e-Wallet state: 10 Euro (fully loaded) Bill 9,21 Euros Change to be returned 0,79 Euros

Peer2Peer Communication & e-Token exchange demonstration: 

Peer2Peer Communication & e-Token exchange demonstration Case Study 3 – Online transaction – Money withdrawn diretcly from bank upon request PeerA pays the bill to PeerB PeerA e-Wallet state: Empty PeerB e-Wallet state: Empty Bill 5.00 Euros PeerA Auto withdraw feature enabled

Conclusions and further work: 

Conclusions and further work The presented coin allocation and dispensing algorithms allow optimal to near-to-optimal multiple offline transactions of fixed coin denominations Simple yet effective networking protocol that enabled peer co-operation and successful transaction environment Further statistical analysis on a lager scale basis for the coin allocation algorithm.

Thank you for your attention: 

Thank you for your attention