I want to encrypt a short plain text (i.e., 30bit), and the requirement is that length of cipher text is the same as the short plain text.
It seems that stream encryption methods like CFB-8 satisfies my requirement. My question is that
What is the cracking time of CFB-8 in brute-force-attack? Does the cracking time only depend on the key length?
Does the length of plain text influence the cracking time? if so, what's the relationship?
Are there any better methods for my requirement?