Automating the Development of Chosen Ciphertext Attacks

Explore the automation of chosen ciphertext attacks in this 43-minute presentation from the Workshop on Attacks in Cryptography 2 (WAC2). Delve into format oracles, authenticated encryption, and mitigation strategies. Learn about the high-level and basic approaches to automation, including the use of theory solvers and their pros and cons. Understand the process of defining initial constraints, identifying experiments, and iteratively adding new constraints. Examine the concept of approximate counting and its application. Compare human vs. machine approaches using examples like PKCS #7 padding and a newly developed bitwise-padding scheme. Gain insights into the future of automated cryptographic attacks and their implications for security.

Automating the Development of Chosen Ciphertext Attacks
Format oracles
What about AE? Of course we know how to mitigate these issues
High-level approach
Basic approach
Theory solvers: Good/bad
Define initial constraints
Step 2: Identify experiment (toy)
Conduct experiment
Add new constraint
Repeat / Solve
Approximate counting
Step 2: revised
PKCS #7 padding: machine
Human vs. machine
Example 2: Bitwise padding Developed a new bitwise-padding scheme
Summary