2
votes
2answers
320 views

Can I build a secure tweakable block cipher from a normal one by adding key and tweak?

Let (E,D) be a secure block cipher. Consider the following tweakable block cipher: ...
6
votes
1answer
183 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 ...