What Is Device Attestation?

Device attestation is a security mechanism that provides cryptographic proof that a credential or operation originates from a genuine, uncompromised device meeting specific security requirements. It allows issuers and verifiers to confirm that a mobile driver's license or other verifiable digital credential is stored on legitimate hardware with appropriate protections, not on a compromised device, emulator, or fraudulent system.

The trust problem

When a DMV issues a mobile driver's license, it needs assurance that the credential will be stored securely and protected from unauthorized access. If the credential ends up on a compromised device, one with malware, modified software, or weakened security, the protections built into the credential system could be undermined. An attacker might extract private keys, copy credentials, or manipulate the presentation process.

Similarly, when a verifier accepts a credential presentation, they benefit from knowing the credential comes from a device with intact security protections. Device attestation provides this assurance through cryptographic proof, rather than relying on trust assumptions.

How device attestation works

Modern smartphones include hardware-backed security features that can generate attestation statements. These statements are cryptographically signed by the device manufacturer and confirm specific properties about the device and its security state.

During credential provisioning, the wallet application requests an attestation from the device's secure hardware. This attestation confirms that cryptographic keys were generated within tamper-resistant hardware, and the device's operating system hasn't been modified or compromised. The security features required for credential storage are present and active, and the device meets the manufacturer's security standards.

Attestation is signed by an attestation key with a certificate chain rooted in a platform trust anchor (for example, Apple’s attestation infrastructure on iOS, and Android attestation roots used by the Android ecosystem). The issuer can verify this signature to confirm the attestation is genuine and came from real hardware, not a software emulator or compromised system.

What device attestation proves

Device attestation can confirm several important security properties. Key protection confirms that private keys were generated in secure hardware and cannot be exported. Device integrity indicates the operating system and security features haven't been tampered with. Hardware authenticity verifies that the device is genuine hardware from a known manufacturer. The security level confirms that the device meets specific security requirements appropriate for the use case.

This information helps issuers make informed decisions about credential provisioning. A DMV might require stronger attestation for high-assurance credentials, ensuring they're only issued to devices with robust security protections.

Device attestation in digital identity

For mobile driver's licenses, device attestation serves multiple purposes. During issuance, the DMV can verify that the credential will be stored on a device with hardware-backed key protection, ensuring the credential cannot be easily copied or extracted. This provides confidence that device binding will be effective.

During presentation, verifiers can receive attestation that the credential is being presented from a legitimate device with intact security. This helps distinguish genuine presentations from potential fraud attempts using compromised or emulated devices.

Device attestation also supports wallet certification. Certification programs can require wallets to demonstrate they properly use device security features, with attestation providing evidence of compliance.

Privacy considerations

Device attestation must be implemented carefully to avoid creating privacy risks. Attestation should not include unique device identifiers that could enable tracking across presentations. Well-designed systems utilize attestation to demonstrate security properties without disclosing information that could link the device to a specific individual across different verifiers.

The goal is to confirm "this device is secure enough" without revealing "this is the same device we saw yesterday." Privacy-preserving attestation architectures achieve this by proving class membership (i.e., this is a secure device) rather than specific identity (i.e., this is device serial number XYZ).

The foundation for secure credentials

Device attestation is critical for high-assurance digital identity systems. It ensures that the cryptographic protections built into credential formats actually function as intended, because the underlying hardware and software environment is trustworthy. Without device attestation, issuers must simply hope that credentials end up on secure devices, with it, they have cryptographic proof.