Applied Cryptography¶

Fall 2022, University of Waterloo.

Definition¶

Cryptography is about securing communications in the presence of malicious adversaries.

Multi-disciplinary:

mathematics(design)
computer science(protocols, attack)
Engineering(implementation)

Basic Goals¶

Confidentiality: keep data secret
Data Integrity: keep data not being altered (by unauthorized means)
Data Origin Authentication: collaborating the source of the data
Non-repudiation: Prevent from denying previous commitments

States of Information (that can be attacked)¶

Data at rest: disk
Data at transit: internet, wireless
Data at processing: CPUs

There are different techniques to attack at all stages.

Is TLS really safe?¶

Possible invisible security vulnerabilities:

weak crypto methods: (AES, HMAC, RSA)
Quantum attacks
weak random numbers
Fraudulent certificates
Software bugs
Phishing attacks(fake sites)
Only protect "transit" process (how and where they store those data?)
NSA(national Security Agency)