In key lifecycle management, key destruction is a critical phase to ensure that cryptographic keys are permanently rendered unusable after their intended use. Methods for key destruction include:
Cryptographic Erasure (Crypto Shredding): This method involves overwriting the key material in storage with random data or zeros, making it irrecoverable. It is commonly used in software-based key management systems.
Physical Destruction: For hardware security modules (HSMs) or storage devices containing keys, physical destruction (e.g., shredding, incineration, or degaussing) ensures the key cannot be recovered.
Key Zeroization: This is a hardware-level process where the key is erased from memory by setting all bits to zero, typically used in secure enclaves or trusted platform modules (TPMs).
Revocation and Expiration: While not direct destruction, revoking a key and ensuring it expires prevents further use. The key may still exist but is no longer valid for cryptographic operations.
Example: In a cloud environment, when a customer no longer needs a symmetric encryption key, they can use Tencent Cloud's Key Management Service (KMS) to perform cryptographic erasure, ensuring the key is securely overwritten and unrecoverable. For hardware-based keys stored in Tencent Cloud HSM, physical destruction or zeroization can be initiated to permanently eliminate the key.