Key lifecycle is the complete path a cryptographic key follows from creation, through storage and use, to rotation, revocation, expiration, and final deletion. In a secure system, the lifecycle defines not just how a key works, but how long it remains trusted and who can access it.
This matters because most real-world attacks target key management rather than the encryption algorithm itself. If a key is exposed, reused too long, or never properly deleted, an attacker may decrypt data, impersonate services, or sign malicious requests. Defenders reduce that risk with short-lived keys, regular rotation, strict access controls, hardware-backed storage, and reliable revocation. A strong key lifecycle also supports recovery and auditing, so a system can replace compromised keys without breaking legitimate access. In practice, the security of encryption depends on the lifecycle as much as on the cipher.