KeyAttestation in Android Nougat API 24

KeyAttestation in Android Nougat API 24

Android Nougat (API 24) introduced KeyAttestation, a security feature that allows applications to obtain evidence of the device’s integrity and the trustworthiness of the keys used for cryptographic operations. This enhances the security of sensitive data and transactions by making it harder for attackers to compromise devices and steal data.

Understanding KeyAttestation

KeyAttestation in a Nutshell

KeyAttestation is a mechanism where a device’s Trusted Execution Environment (TEE) provides a cryptographic attestation statement that certifies the device’s integrity and the authenticity of cryptographic keys generated within the TEE.

Why KeyAttestation Matters

• Enhanced Security: KeyAttestation makes it harder for attackers to forge keys or compromise the device, protecting sensitive data and transactions.
• Trustworthiness: It allows applications to trust the device and its cryptographic operations, ensuring data integrity and authenticity.
• Stronger Authentication: KeyAttestation strengthens authentication mechanisms, making it more difficult for attackers to impersonate legitimate users.

KeyAttestation in Android Nougat

KeyAttestation APIs

Android Nougat provides several APIs for KeyAttestation, allowing developers to integrate it into their applications:

• KeyAttestationManager: This class is the main entry point for KeyAttestation. It allows you to request attestation statements and interact with the TEE.
• AttestationRequest: This class defines the request parameters for an attestation statement, including the key type and the desired attestation level.
• AttestationStatement: This class represents the attestation statement returned by the TEE. It contains information about the device and the keys used for cryptography.

KeyAttestation Flow

Here’s a basic overview of the KeyAttestation flow:

1. Request Attestation: The application requests an attestation statement using the KeyAttestationManager.
2. TEE Verification: The TEE verifies the device’s integrity and the authenticity of the cryptographic key.
3. Attestation Statement Generation: The TEE generates an attestation statement containing relevant information.
4. Attestation Statement Return: The TEE returns the attestation statement to the application.
5. Validation: The application validates the attestation statement to ensure its authenticity and integrity.

Implementation Example

Code Snippet

import android.security.keystore.KeyAttestationManager;
import android.security.keystore.AttestationRequest;
import android.security.keystore.AttestationStatement;

// Request an attestation statement
KeyAttestationManager attestationManager = KeyAttestationManager.getInstance(context);
AttestationRequest request = new AttestationRequest.Builder()
    .setKeyType("RSA")
    .setAttestationLevel(AttestationRequest.AttestationLevel.BASIC)
    .build();
AttestationStatement attestationStatement = attestationManager.generateAttestationStatement(request);

// Validate the attestation statement
// ...

Benefits of KeyAttestation

Advantages for Developers

• Enhanced Security: KeyAttestation helps developers build more secure applications by protecting against key forgery and device compromise.
• Trustworthiness: It allows applications to trust the device and its cryptographic operations, enhancing user confidence.
• Simplified Implementation: The KeyAttestation APIs simplify the integration process, making it easier for developers to leverage this security feature.

Advantages for Users

• Increased Security: KeyAttestation protects sensitive data and transactions, safeguarding users from attacks.
• Improved Privacy: It helps ensure the authenticity and integrity of data, enhancing user privacy.
• Enhanced User Experience: KeyAttestation can lead to a more secure and reliable user experience.

Comparison: KeyAttestation vs. Traditional Security Measures

Conclusion

KeyAttestation is a valuable security feature introduced in Android Nougat API 24. By leveraging the TEE, it provides evidence of device integrity and key authenticity, significantly enhancing the security of sensitive data and transactions. Developers can integrate KeyAttestation into their applications to build more secure and trustworthy experiences for users.