OpenPGP is a proven standard for storing encrypted data, and for managing encryption keys. OpenPGP was standardized in 1997, and is widely supported.
OpenPGP is the most widely used method to encrypt mails. It is supported by most mail programs either natively, or using a plugin.
OpenPGP can be used to protect data at rest, say backups or passwords. With OpenPGP you can be confident that you can still read your data after decades.