DAA-A: Direct Anonymous Attestation with Selective Disclosure

A professional C implementation of the Direct Anonymous Attestation (DAA) - Variant A protocol, featuring attribute-based credentials and selective disclosure. This library leverages the security of mbedTLS and the high-performance pairing-friendly curves of MIRACL Core.

---

🚀 Overview

DAA-A is a cryptographic protocol that allows a hardware or software "Holder" to prove their legitimacy to a "Verifier" without revealing their unique identity. This implementation extends the core DAA capability by adding Attribute-Based Credentials, allowing the holder to:

1. Prove possession of a Verifiable Credential (VC) issued by a trusted authority.
2. Selectively disclose only specific attributes (e.g., "Age > 18") while keeping others cryptographically hidden.
3. Ensure "Unlinkability": Multiple presentations by the same holder cannot be linked together by the verifier.

Key Features

• Bilinear Pairings: Built on the Barreto-Naehrig (BN-P256) pairing-friendly curve.
• Selective Disclosure: Holder-controlled privacy at the attribute level.
• Zero-Knowledge Proofs: Uses Schnorr-style proofs for attribute commitments.
• Security-First Design: Includes secure memory zeroization for sensitive secret material.
• Professional Logging: Structured diagnostic output for protocol monitoring.

---

🛠 Building the Project

Prerequisites

• CMake (version 3.10 or higher)
• GCC or Clang compiler
• Make or another build system supported by CMake
• Internet connection (to fetch mbedTLS and MIRACL Core dependencies during the first build)

Build Instructions

The project uses a standard CMake workflow. A helper script is provided for convenience.

# Option 1: Using the helper script
chmod +x build.sh
./build.sh

# Option 2: Manual CMake build
mkdir -p build && cd build
cmake ..
make -j$(nproc)

---

🧪 Testing and Demonstration

The project includes a comprehensive demonstration suite that exercises the full protocol lifecycle: Context Setup → Key Generation → Issuance → Presentation → Verification.

Running Tests

Use the provided test script to run various scenarios (hidden attributes, full disclosure, etc.):

chmod +x run_tests.sh
./run_tests.sh

Manual Execution

You can run the demonstration binary directly with custom parameters:

# Usage: ./build/daa-a <num_attributes> <disclosure_comma_separated>
# Example: 5 attributes, disclose 1st and 3rd (1=Visible, 0=Hidden)
./build/daa-a 5 1,0,1,0,0

---

📚 Technical Architecture

• include/daa-a/: Public API headers and data structure definitions.
• src/daa-a.c: Core protocol logic for holders and verifiers.
• src/vc_issuer.c: Issuer-side operations (Keygen and Credential Signing).
• src/cryptoutils.c: Low-level wrappers for MbedTLS and MIRACL integration.
• app/main.c: Command-line demonstration application.

---

🤝 Acknowledgments

This implementation is made possible by the following open-source projects:

• mbedTLS: Used for core ECC operations, SHA-256 hashing, and constant-time memory utilities.
• MIRACL Core: Provides the high-performance implementation of the BN-P256 pairing-friendly curve and bilinear pairing primitives.

---

👥 Maintainers

• Stefanos Vasileiadis (svasileiadis@ubitech.eu) - Software Leading Engineer
• Thanassis Giannetsos (agiannetsos@ubitech.eu) - Scientific Lead
• Panagiotis Gouvas (pgouvas@ubitech.eu) - Technical Coordination

---

📄 License

This project is licensed under the Apache License, Version 2.0. See the LICENSE file for details.

Copyright 2025-2026 UBITECH Ltd (https://ubitech.eu)