Managing the cryptographic keys within Trusted Execution Environment

The Trusted Platform Module (TPM) is a dedicated hardware component designed to enhance the security of computing systems. It provides a root of trust for the platform and offers various security-related functions. The primary role of a hardware TPM involves secure storage, key management, and attestation.

Cryptographic key management in a Trusted Execution Environment (TEE) involves the generation, storage, and usage of cryptographic keys to ensure the security of operations within the TEE.

1. Key Generation:

Flow Diagram:

+---------------------+
|  TEE Initialization |
+---------------------+
           |
           v
+---------------------+
|   Key Generation    |
|   (Asymmetric,      |
|    Symmetric, etc.)  |
+---------------------+
           |
           v
+---------------------+
|    Key Storage      |
+---------------------+

• During the initialization of the TEE, cryptographic keys are generated. These keys can be either symmetric or asymmetric, depending on the specific requirements of the TEE application.
• Asymmetric keys usually include a public-private key pair, while symmetric keys are a single shared secret.
• After generation, the keys need to be securely stored within the TEE to prevent unauthorized access.

2. Key Storage:

Flow Diagram:

+---------------------+
|    Key Storage      |
+---------------------+
           |
           v
+---------------------+
|   Secure Storage    |
|   within the TEE    |
+---------------------+
           |
           v
+---------------------+
|   Access Controls   |
|   (Hardware-based   |
|   and Software-based|
|   protections)      |
+---------------------+

• The generated cryptographic keys are stored securely within the TEE. This storage needs to be resistant to various attacks, such as side-channel attacks or unauthorized access attempts.
• Access controls, both hardware-based and software-based, are implemented to restrict access to the stored keys. Only authorized processes or entities within the TEE should have access to these keys.

3. Key Usage:

Flow Diagram:

+---------------------+
|    Key Usage        |
+---------------------+
           |
           v
+---------------------+
|   Cryptographic     |
|   Operations        |
|   (Encryption,       |
|   Decryption,        |
|   Signing, etc.)     |
+---------------------+
           |
           v
+---------------------+
|   Result of         |
|   Cryptographic     |
|   Operation         |
+---------------------+

• Cryptographic keys stored within the TEE are used for various operations, such as encryption, decryption, signing, or other cryptographic functions.
• These operations are performed within the secure environment of the TEE, ensuring the confidentiality and integrity of the sensitive data involved.

4. Key Lifecycle Management:

Flow Diagram:

+---------------------+
|  Key Lifecycle       |
|  Management         |
+---------------------+
           |
           v
+---------------------+
|   Key Update/       |
|   Rotation          |
+---------------------+
           |
           v
+---------------------+
|   Key Revocation/   |
|   Deletion          |
+---------------------+

• Key lifecycle management includes processes for key update or rotation to enhance security over time.

• In case a key becomes compromised or is no longer needed, key revocation or deletion processes are implemented to ensure that the key is no longer used.

• Key updates and revocations should be managed carefully to avoid disruptions to ongoing operations that rely on these keys.

In summary, cryptographic key management in a TEE involves key generation, secure storage, access controls, key usage, and key lifecycle management. These processes collectively contribute to maintaining the confidentiality and integrity of cryptographic operations within the Trusted Execution Environment.