Key rotation
Key rotation introduces new key material. Older data and backups need a plan for the key versions they still require for decryption.
Plan changes to key material
Key rotation replaces cryptographic key material already in use with new material. A defined period, usage limits or a security incident may trigger it. An appropriate rotation interval depends on the method, usage and protection requirements; no single interval in days suits every application.
Keep older data linked to its keys
During a planned change in a fictional document portal, the application starts encrypting new files with v2 instead of v1. These labels represent key versions, not key values. Files already stored are not thereby automatically encrypted with the new version.
The team must decide whether to re-encrypt older data or retain its previous key version for decryption under controlled access. Existing backups may also need the old version. Before permanently removing it, the team must establish that required data no longer depends on it. A version identifier alone does not replace the associated key material.
Handle suspected exposure separately
If exposure is suspected, the normal rotation calendar is insufficient. The incident plan must also address access to affected keys, existing data and a safe transition. A new version removes neither plaintext already stolen nor unauthorised access to key management that remains active.
Sources
Related terms
- Envelope encryptionEnvelope encryption separates the data key from the key protecting it. The encrypted file and wrapped data key need to be managed together.
- Audit logAn audit log makes important application events traceable. Actor, action, affected object and outcome need to be readable together.
- Data retention policyA data retention policy defines the purpose, start, duration and end of storage. Deletion jobs and copies must be addressed in the implementation.
- Data minimisationData minimisation limits personal data to what is adequate, relevant and necessary for a defined purpose.
- Password saltingPassword salting gives each new password hash its own random additional value. The salt is stored alongside it and does not need to be secret.
- Argon2Argon2 is a family of memory-intensive password hash functions. The variant, memory use and runtime must suit security and operational requirements.
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