Keysets

A keyset is a collection of cryptographic keys managed as a unit. It provides a way to store, rotate, and apply multiple keys for cryptographic operations. In many libraries, a keyset is separate from the actual key material and is used to reference keys stored securely.

In typical implementations, a keyset contains multiple keys, each with a unique identifier, a status (enabled, disabled, destroyed), a purpose (encryption, decryption, signing, verification), and a flag indicating which key is primary. Some designs separate the key metadata from the key material, with the material stored in a secure store and referenced by the key entries.

The keyset supports rotation: a new key can be added to the set and designated as primary, while older keys remain in the set to decrypt or verify legacy data. The primary key is used for new operations, and keys can be disabled or destroyed when no longer needed. Backups and careful access control are required to preserve data integrity.

Keysets are central in cryptographic libraries and cloud services. For example, Google’s Tink library uses a Keyset and a KeysetHandle to manage keys for a cryptographic primitive, while cloud KMS offerings organize keys into key rings or keysets for centralized management. They enable transparent key rotation without changing application code.

Security considerations include restricting access, monitoring usage, ensuring proper lifecycle management, protecting key material with hardware security modules or secure enclaves, and implementing auditing and key revocation for compromised keys.

See also Key management, Key rotation, Public-key cryptography, Tink, HSM.