SMARTDATA: Leveraging Blockchain to Securely Capture & Verify Scientific Provenance Data

Transcription

1 UT DALLAS Erik Jonsson School of Engineering & Computer Science SMARTDATA: Leveraging Blockchain to Securely Capture & Verify Scientific Provenance Data Dr.Murat Kantarcioglu Joint work with Aravind Ramachandran University of Texas at Dallas

2 What is Data provenance? Data provenance provides proof of who produced/modified the data,what process was used to change the data and the time when the change was made.

3 Significance of Data Provence in research Data provenance in scientific research ensures that the results for the research are valid and trustworthy. Data provenance ensures: Data Quality Data Traceability Reproducibility Data Modified Data Process Data Provenance Who / Origin Which Process When What change How

4 Significance of Data Provence in research

5 How We Can Automatically Capture/Represent Provenance Information?

6 OPM : Open Provenance Model OPM is a data provenance model that allows to express all the causes of an data item. In OPM, it is assumed that the provenance of objects (whether digital or not) can be represented by an annotated causality graph R1,R2,R3 Rule for triggering. Acc1,2,3 : Accounts that triggers the process

7 OPM : Nodes In OPM, provenance graphs consist of three types of nodes. Artifacts: represent an immutable piece of state, which may be physical object, or a digital representation in a computer system. Processes represent actions performed on or caused by artifacts, and resulting in new artifacts. Agents represent contextual entities acting as a catalyst of a process, enabling, facilitating, controlling, or affecting its execution. Artifact Process Agent

8 OPM : Edges A used(r) P P Ag wasgeneratedby(r) wascontrolledby(r) A P P1 A1 wastriggeredby wasderivedfrom P2 A2 Edge labels are in the past to express that these are used to describe past executions

9 OPM Example

10 How to capture OPM using Smart Contracts?

11 Ledgers

12 Digital Ledger Without a Trusted Party? A digital ledger in which transactions made in bitcoin or another cryptocurrency are recorded chronologically and publicly. It is a distributed database that maintains a continuously growing list of data records secured from tampering and revision.

13 Ethereum Ethereum is a public blockchain-based distributed computing platform. It provides a decentralized virtual machine, the Ethereum Virtual Machine (EVM), that can execute peer-to-peer contracts using a cryptocurrency called ether. Ethereum was initially proposed in late 2013 by Vitalik Buterin, a cryptocurrency researcher and programmer. It provides a decentralized platform that runs smart contracts, a Turing complete language. Ethereum is a programmable blockchain. Cryptocurrency used : Ether.

14 Ethereum Virtual Machine The Ethereum Virtual Machine (EVM) is the runtime environment for smart contracts in Ethereum. It is completely isolated, which means that code running inside the EVM has no access to network, filesystem, or other processes. Each and every node of the network runs the EVM. Every node running the EVM ensures consensus across the blockchain.

15 Contracts A contract is a collection of code and data that resides at a specific address on the Ethereum blockchain Contract accounts are able to pass messages between themselves as well as doing practically Turing complete computation. Contracts live on the blockchain in a Ethereum-specific binary format called Ethereum Virtual Machine (EVM) bytecode. Contracts are written in high level languages like Solidity

16 Contracts Contracts in Ethereum should not be seen as something that should be fulfilled or complied with ; autonomous agents that live inside of the Ethereum execution environment, always executing a specific piece of code when poked by a message or transaction having direct control over their own ether balance and their own key/value store to store their permanent state.

17 Smart Data : System overview The Smart data system provides a platform for securely generating and storing data provenances information for sensitive data sets. The system is build on top of the public Ethereum blockchain and an off-chain javascript module

18 Smart Data : System overview

19 On chain module : Ethereum Smart Contracts A contract in the sense of Solidity is a collection of code (its functions) and data (its state) that resides at a specific address on the Ethereum blockchain. Smart contracts can be viewed as computer protocols that facilitate, verify, or enforce the negotiation or performance of an actual paper contract. Executed only when they are called.

20 On Chain Module : Document_Track Contract The main contract of the system. Consists of functions : to add a new document, grant revoke access to a document, track changes for a document. Responsible for tracking Changes

21 On Chain Module : Document_Track Contract Document_Track tracks the changes to a document by generating log events. Each change events are of the format: Change (doc_id,addr,ency_text,process,opm,sig); Where Ency_txt = ENC key (Doc_id Curr_hash Prev_hash Link ts Initiator Address)

22 OPM Representation OPM representation is mainly done in the model of Graphx model Each type of like is assigned a number Example : To represent Document change Address -1-process-2-artifact-3-hashes Where numbers represents the type of links 1- was triggered by 2- was generated by 3 - Used

23 Voting Process Initiator of change, submits change to vote contract with a deposit. Timer starts for voting period. Off-chain module verifies the change and notifies voters. Voters checks result and casts vote. Timer calls terminate after voting period. Vote contract accepts or rejects change based on majority vote (x % of total). The contract refunds/rewards deposit to initiator /voter if change is accepted/rejected

24 Off chain module : javascript application The off-chain module implemented using MeteorJS. Runs on the browser of each person The module forms an interface between the smart contracts and users. Implements Event watchers to trigger verifications scripts Notifies users of the result of the script. Timer script calls terminate at the end of the voting period. No NEED for HUMAN INTERVENTION if change verification code is automatic Event Watcher Timer Contract Interface

25 Experiment Setup : Clinical trials The system was tested on Clinical Drug trial scenario. The trial is to find dosage information about an experimental Drug Patient set 1 Doc1 The drug trial is done for a 12 month period on a total data set of 300 patients. Each month the researchers would updated the observation document based on the reactions of the patient to the drug. Patient set 2 Doc3 Trial Result Verification of the change includes checking if any of the patients are missing from successive iterations of the drug trials Patient set 3 Doc3 Clinical Drug trials

26 Document Format PATIENT ID PRIMARY RACE SAMPLE TYPE DISEASE TYPE DOSAGE SIDE EFFECTS GENIE-DFCI White Primary Non-Small Cell Lung Cancer None GENIE-DFCI White Metastasis Breast Cancer GENIE-DFCI Black Primary Thyroid Cancer GENIE-DFCI White Metastasis GENIE-DFCI Asian Metastasis Non-Small Cell Lung Cancer Non-Small Cell Lung Cancer GENIE-DFCI White Primary Ovarian Cancer GENIE-DFCI White Primary Bladder Cancer none none Died Vomiting none Nausea

27 Vote :Gas Used Gas used/votes Gas Used Transaction Count

28 Vote :Cumulative Gas Used Cumulative Gas Used/Transactions Cumulative Gas Used Transaction Count

29 Change Log: Gas Used Gas used / Termination Gas Used Transaction Count Average gas used :249812

30 Change Log: Gas Used Cumulative Gas Used Gas Used Cumulative Gas Used Transaction Count

31 Conclusion We have implemented a decentralized system for generating secure immutable data provenance for scientific experiments using Blockchain technology. The event log of the contract is publically available for user to access and verify the authenticity of changes. Encryption ensure that only authorized user can access the provenance event logs for verification The developed system was implemented and successfully tested in a real world scenario of Clinical drug trials. Future work: Understanding automatic off-chain verification settings

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