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Balancing Confidentiality and Transparency for Blockchain-based Process-Aware Information Systems

Alessandro Marcelletti, Edoardo Marangone, Michele Kryston, Claudio Di Ciccio

TL;DR

The paper tackles the challenge of enabling transparent, auditable execution in blockchain-based PAISs while preserving confidentiality for sensitive data. It introduces CONFETTY, an architecture that uses public smart contracts for process control coupled with Ciphertext-Policy MAABE to restrict access to confidential data stored off-chain, with notarization on-chain for auditability. A threat-model analysis and a healthcare-oriented prototype demonstrate feasible performance and scalability, showing that confidentiality can be maintained without sacrificing public verifiability. The work has practical implications for regulated domains like healthcare and sets directions for further decentralization, stronger security analyses, and encrypted computation over confidential data.

Abstract

Blockchain enables novel, trustworthy Process-Aware Information Systems (PAISs) by enforcing the security, robustness, and traceability of operations. In particular, transparency ensures that all information exchanges are openly accessible, fostering trust within the system. Although this is a desirable property to enable notarization and auditing activities, it also represents a limitation for such cases where confidentiality is a requirement since interactions involve sensitive data. Current solutions rely on obfuscation techniques or private infrastructures, hindering the enforcement capabilities of smart contracts and the public verifiability of transactions. Against this background, we propose CONFETTY, an architecture for blockchain-based PAISs to preserve confidentiality and transparency. Smart contracts enact, enforce and store public interactions, while attribute-based encryption techniques are adopted to specify access grants to confidential information. We assess the security of our solution through a systematic threat model analysis and evaluate its practical feasibility by gauging the performance of our implemented prototype in different scenarios from the literature.

Balancing Confidentiality and Transparency for Blockchain-based Process-Aware Information Systems

TL;DR

The paper tackles the challenge of enabling transparent, auditable execution in blockchain-based PAISs while preserving confidentiality for sensitive data. It introduces CONFETTY, an architecture that uses public smart contracts for process control coupled with Ciphertext-Policy MAABE to restrict access to confidential data stored off-chain, with notarization on-chain for auditability. A threat-model analysis and a healthcare-oriented prototype demonstrate feasible performance and scalability, showing that confidentiality can be maintained without sacrificing public verifiability. The work has practical implications for regulated domains like healthcare and sets directions for further decentralization, stronger security analyses, and encrypted computation over confidential data.

Abstract

Blockchain enables novel, trustworthy Process-Aware Information Systems (PAISs) by enforcing the security, robustness, and traceability of operations. In particular, transparency ensures that all information exchanges are openly accessible, fostering trust within the system. Although this is a desirable property to enable notarization and auditing activities, it also represents a limitation for such cases where confidentiality is a requirement since interactions involve sensitive data. Current solutions rely on obfuscation techniques or private infrastructures, hindering the enforcement capabilities of smart contracts and the public verifiability of transactions. Against this background, we propose CONFETTY, an architecture for blockchain-based PAISs to preserve confidentiality and transparency. Smart contracts enact, enforce and store public interactions, while attribute-based encryption techniques are adopted to specify access grants to confidential information. We assess the security of our solution through a systematic threat model analysis and evaluate its practical feasibility by gauging the performance of our implemented prototype in different scenarios from the literature.

Paper Structure

This paper contains 19 sections, 9 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Example, Problem Illustration and Requirements
  3. Background and State of the Art
  4. Background
  5. Blockchain technology.
  6. Attribute-based Encryption.
  7. State of the Art
  8. The CONFETTY Architecture
  9. Functional Viewpoint
  10. Information Viewpoint
  11. A note on decryption keys.
  12. Evaluation
  13. Threat Model
  14. Implementation
  15. Execution Analysis
  16. ...and 4 more sections

Figures (9)

  • Figure 1: BPMN choreography diagram of an X-ray diagnostic analysis runningExample
  • Figure 2: A graphical sketch of the CONFETTY functionalities, users, artifacts, and interfaces
  • Figure 3: The deployment diagram of CONFETTY
  • Figure 4: Communication diagram of the instantiate functionality, with a snapshot of public state
  • Figure 5: Communication diagram of the transact functionality
  • ...and 4 more figures