Fountain and plaques at a Buddhist temple.

Cryptography Flowcharts

Know These!

Make sure that you can draw your own versions of these pictures.

Expect multiple questions about who uses which key first, or which key last, in these situations.

Privacy with asymmetric cryptography.
Authentication with asymmetric cryptography.
Both privacy and authentication with asymmetric cryptography.
Creating and verifying a digital signature.
Creating and verifying an HMAC.
Goal Sender uses Receiver uses
Confidentiality Receiver's public key Receiver's private key
Authentication Sender's private key Sender's public key
Confidentiality
& Authentication
Receiver's public key
Sender's private key
Sender's public key
Receiver's private key
Digital Signature Sender's private key Sender's public key
HMAC Shared secret key Shared secret key

Use certificates (thus PKI) so you can trust the validity of public keys.

Use Diffie-Hellman to negotiate a shared secret.

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