Kerckhoffs's principle

  "The principle holds that a cryptosystem should be secure, even if everything
  about the system, except the key, is public knowledge"

  In other words: The security of the system should not rely on the secrecy of
  the methods, but on the secrecy of the keys.

- Symmetrical / Asymmetrical encryption

Block Cipher modes of operations:

  - ECB (Electronic Code Block)
  - CBC (Chpher Block Chaining)


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