Ensure thread safety - Ciphers

[MrSebastian]

          _:warning: Potential issue_

Ensure thread safety by avoiding shared Cipher instances

Cipher instances are not thread-safe. Injecting them as shared beans and storing them as class fields may lead to concurrency issues in a multi-threaded environment.

Recommend obtaining new Cipher instances within each method call or configuring the Cipher beans with prototype scope to provide a new instance per injection.

Also applies to: 31-37

Originally posted by @coderabbitai[bot] in #635 (comment)