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A Low-Cost Privacy-Preserving Digital Wallet for Humanitarian Aid Distribution

Eva Luvison, Sylvain Chatel, Justinas Sukaitis, Vincent Graf Narbel, Carmela Troncoso, Wouter Lueks

TL;DR

This work formalizes needs into functional, deployment, security, and privacy requirements, and design a privacy-preserving digital wallet for aid distribution, and proves the solution's security and privacy properties, and shows it is practical at scale.

Abstract

Humanitarian organizations distribute aid to people affected by armed conflicts or natural disasters. Digitalization has the potential to increase the efficiency and fairness of aid-distribution systems, and recent work by Wang et al. has shown that these benefits are possible without creating privacy harms for aid recipients. However, their work only provides a solution for one particular aid-distribution scenario in which aid recipients receive a pre-defined set of goods. Yet, in many situations it is desirable to enable recipients to decide which items they need at each moment to satisfy their specific needs. We formalize these needs into functional, deployment, security, and privacy requirements, and design a privacy-preserving digital wallet for aid distribution. Our smart-card-based solution enables aid recipients to spend a pre-defined budget at different vendors to obtain the items that they need. We prove our solution's security and privacy properties, and show it is practical at scale.

A Low-Cost Privacy-Preserving Digital Wallet for Humanitarian Aid Distribution

TL;DR

This work formalizes needs into functional, deployment, security, and privacy requirements, and design a privacy-preserving digital wallet for aid distribution, and proves the solution's security and privacy properties, and shows it is practical at scale.

Abstract

Humanitarian organizations distribute aid to people affected by armed conflicts or natural disasters. Digitalization has the potential to increase the efficiency and fairness of aid-distribution systems, and recent work by Wang et al. has shown that these benefits are possible without creating privacy harms for aid recipients. However, their work only provides a solution for one particular aid-distribution scenario in which aid recipients receive a pre-defined set of goods. Yet, in many situations it is desirable to enable recipients to decide which items they need at each moment to satisfy their specific needs. We formalize these needs into functional, deployment, security, and privacy requirements, and design a privacy-preserving digital wallet for aid distribution. Our smart-card-based solution enables aid recipients to spend a pre-defined budget at different vendors to obtain the items that they need. We prove our solution's security and privacy properties, and show it is practical at scale.

Paper Structure

This paper contains 29 sections, 4 theorems, 2 equations, 6 figures, 6 algorithms.

Table of Contents

  1. Introduction
  2. Problem and Solution Overview
  3. System Model
  4. Requirements
  5. Functional requirements
  6. Deployment requirements
  7. Security requirements
  8. Privacy requirements
  9. Solution Sketch
  10. Related Work
  11. Our Solution
  12. Cryptographic Building Blocks
  13. Syntax
  14. Solution Details
  15. Security and Privacy Analsis
  16. ...and 14 more sections

Key Result

Theorem 1

The system is secure against overspending providing that the smart card is a SE and the channel with smart cards is authenticated.

Figures (6)

  • Figure 1: Workflow of our digital wallet. The user interacts with the registration station which allocates a budget and returns a smart card. The user transacts with a vendor who later contacts the reclaim station to reclaim the transaction. An auditor can check the correctness of this reclaim.
  • Figure 2: Overview of the solution. See Section \ref{['sec:sol:syntax']} for details.
  • Figure 3: Registration protocol
  • Figure 4: Transaction protocol
  • Figure 5: Evaluation of ORAM costs per transaction. The plain line corresponds to the total ORAM execution runtime (in s) while the dashed line corresponds to the transfer time only. The bar plots refer to the measure of the communication costs (sent/received by the card) in kB.
  • ...and 1 more figures

Theorems & Definitions (12)

  • Definition 1
  • Theorem 1
  • proof : Proof Sketch
  • Definition 2
  • Theorem 2
  • proof : Proof Sketch
  • Definition 3
  • Theorem 3
  • proof : Proof Sketch
  • Definition 4
  • ...and 2 more