AES: modes, keys and implementation

AES is a symmetric block cipher. Using it in a system also requires a mode of operation, key management and correct implementation.

When reviewing its use, I look at:

• Whether the application needs confidentiality, integrity and authentication.
• How keys are generated, stored and replaced.
• The selected mode’s requirements for nonces or initialization vectors.
• Which cryptographic library provides the implementation.

The guide below introduces the algorithm.