2
votes
2answers
916 views

Which categories of cipher are semantically secure under a chosen-plaintext attack?

I am trying to get my head around the circumstances under which a cipher is (or is not) semantically secure under a chosen-plaintext attack. I can't seem to find a good reference explaining this. I ...
5
votes
2answers
492 views

Practical necessity of semantic security under chosen plain text attack (CPA) in CBC mode

I was not able to understand why we practically need a CPA security in Cipher Block Chaining. (which insist on having a random IV), let say if the encryption is not CPA secure i.e , the adversary can ...
6
votes
1answer
212 views

Message space in security definitions

What is the message space in the following example and how does a message space relate to a security definition? I mean, what difference does it make to such a definition if your message space is ...