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ZKP-IDFS: A Zero-Knowledge Proof-Based Digital Identity Framework for Financial Inclusion in Sub-Saharan Africa

> A privacy-preserving digital identity solution designed to address financial exclusion in Sub-Saharan Africa. It utilizes Groth16 zk-SNARKs and Pedersen vector commitments, operating over a low-bandwidth USSD/SMS relay channel for accessibility on feature phones without local proof generation.

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#CRYPTOGRAPHY#ZERO-KNOWLEDGE PROOFS#DIGITAL IDENTITY#USSD RELAY#POLYGON ZKEVM
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ZKP-IDFS: A Zero-Knowledge Proof-Based Digital Identity Framework for Financial Inclusion in Sub-Saharan Africa

Research Paper | Published April 15, 2026

Abstract

Financial exclusion remains a critical structural challenge in Sub-Saharan Africa, where millions of adults lack access to formal financial accounts due to the absence of verifiable identity documentation. Existing digital identity initiatives suffer from two primary limitations: centralization risks that create systemic privacy vulnerabilities, and high infrastructure barriers requiring smartphones and reliable broadband networks.

This paper presents ZKP-IDFS, a decentralized, privacy-preserving digital identity framework tailored for financial inclusion in resource-constrained environments. By leveraging Groth16 zk-SNARKs and Pedersen vector commitments, ZKP-IDFS enables individuals to prove identity predicates to financial institutions without disclosing underlying personal attributes.

A novel USSD/SMS proof-relay channel allows feature-phone users on 2G networks to participate without performing local cryptographic proof generation. We present the system architecture, formal security models, and empirical simulation results showing verification latency under 4.2 seconds on 3G and under 14.3 seconds via the USSD relay on 2G networks, with on-chain proof verification costs on Polygon zkEVM below $0.001.

1. The Core Paradox of Identity & Access

In Sub-Saharan Africa, the road to financial inclusion is blocked by a catch-22: you need an identity to open a bank account, but obtaining a state-issued identity document is often slow, expensive, and logistically inaccessible for rural populations.

When digital identity solutions are deployed, they typically follow a centralized model. This introduces two major failure points:

  1. Centralized Honey-Pots: Storing personal data on operator servers exposes citizen registries to data breaches and misuse.
  2. Infrastructure Exclusion: Assuming that every user has a smartphone with local computing power and a 4G connection excludes the substantial segment of the population that relies on basic feature phones.

ZKP-IDFS flips these assumptions by combining decentralized identity architectures with zero-knowledge cryptography, keeping users in control of their data while enabling verification over simple mobile networks.

2. Technical Architecture & Protocols

The ZKP-IDFS framework operates as a five-layer system architecture:

┌─────────────────────────────────────────────────────────┐
│               1. Application Layer (USSD/Web)           │
├─────────────────────────────────────────────────────────┤
│               2. DID & Credential Layer (W3C)           │
├─────────────────────────────────────────────────────────┤
│               3. Cryptographic Layer (zk-SNARKs)        │
├─────────────────────────────────────────────────────────┤
│               4. Proof Relay Layer (USSD / Gateway)     │
├─────────────────────────────────────────────────────────┤
│               5. Blockchain Attestation Layer (zkEVM)   │
└─────────────────────────────────────────────────────────┘

Cryptographic Primitives

  • Groth16 zk-SNARKs: Selected for constant proof sizes (384 bytes) and extremely fast on-chain verification, making it feasible to settle transactions with minimal gas fees.
  • Pedersen Vector Commitments: Used to bind attributes (such as age, residency status, and credit score) to a credential without revealing the values themselves.
  • Poseidon Hash Functions: Optimized for arithmetic circuits, reducing constraint sizes by 8x compared to SHA-256.

The USSD/SMS Proof-Relay Channel

To make zero-knowledge proofs work on feature phones, ZKP-IDFS shifts the computation-heavy proof-generation step away from the user's handset.

  1. The user requests verification via a standard USSD code (e.g., *800#).
  2. The request is routed to a secure, decentralized Attestation Relay Node.
  3. The Node generates the cryptographic proof on behalf of the user using encrypted credentials stored in a decentralized ledger.
  4. The proof is verified on-chain, and access is granted or denied via a text notification.

3. Performance & Evaluation

ZKP-IDFS was simulated across multiple configurations to benchmark latency and on-chain transaction costs.

Verification Latency Benchmarks

  • Budget Android Device (3G network): End-to-end verification (including proof generation, network transmission, and validation) completes in 4.18 seconds.
  • Feature Phone (2G USSD Relay): Relayed proof generation and verification completes in 14.25 seconds.
  • Web Portal (4G/Broadband): Verification completes in 1.10 seconds.

Gas Costs on Polygon zkEVM

Using a Groth16 verifier contract optimized for EVM execution:

  • Verification Gas Cost: ~218,000 gas units.
  • Fiat Cost (under average network conditions): less than $0.001 USD per proof.

4. References & Links