I'm trying to practice and to understand possible scenarios and the basics of symmetric encryption schemes. For the scenarios I listed below, I am not 100% sure of scenarios 1 and 3.
- A symmetric encryption algorithm using non-random/predictable IV that is CPA secure. I do not think this scheme is possible. For example, there is the BEAST attack for the TLS 1.0 scheme on AESCBC encryption schemes. Random IVs are probably needed to make them CPA-secure.
- A symmetric encryption algorithm with equal constant size key, message, and ciphertext space that is semantically secure. It is possible because of OTP One Time Pad, isn't it?
- A symmetric encryption algorithm with equal constant size key and message space of magnitude X, with cipher text space of 2^X that is CPA-secure. I think this is possible as the AES-CBC encryption scheme follows these requirements.
I will be thankful for clarification and help with these scenarios.