encryption is easy, key management is hard
expressioncryptography
The crypto veteran's summary: encrypting data is the easy part; protecting, rotating, and not losing the keys is the hard part.
The algorithms are free and vetted; what fails in practice is the key left in a repository, the certificate nobody renewed, the HSM nobody can operate. It is the two-hard-things joke of the crypto world, and the reason key-management systems exist.