keyencryption

Key encryption, or encryption of cryptographic keys, refers to techniques for protecting keys used to encrypt data. The goal is to prevent unauthorized access to keys, which would compromise all data protected by them. A common concept is the key encryption key (KEK), a separate key used to secure other keys.

Envelope encryption is a typical approach: data is encrypted with a data encryption key (DEK), and the DEK is then encrypted with a KEK. The encrypted DEK and ciphertext are stored together; decryption unwraps the DEK with the KEK to recover the data key, then decrypts the data.

Key wrapping algorithms provide confidential and integrity protection when transferring keys. AES key wrap (RFC 3394) and the padding variant (RFC 5649) are widely used in hardware security modules and cloud key management services.

Effective key management covers secure storage (often in HSMs or cloud KMS), key generation, rotation, distribution, access control, and auditing. Following standards such as FIPS 140-2/140-3 helps meet regulatory requirements. Using unique KEKs or DEKs per dataset enhances security.

Key encryption requires protecting KEKs from disclosure, minimizing in-memory exposure of DEKs during operations, and avoiding weak derivation from passwords. Strong authentication and access controls are essential.

See also: key management, envelope encryption, key wrapping, KEK, DEK, HSM, cloud KMS, FIPS.