Encrypting twice with the same key
From: Daniel Weber (ComeAndSpamIt@gmx.net)
From: "Daniel Weber" <ComeAndSpamIt@gmx.net> Date: Sun, 13 Apr 2003 15:48:53 +0200
Is encrypting twice with the same key safe?
I made up the following:
May f be the encryption transformation, and A be its Matrix with entries
f(x) -> Ax
Then encrypting twice would be f(f(x)) = (AA)x = (A^2)x.
Now, there's much lesser possibilities for the entries of A^2.
That would make brute force a better choice.
Did I think right or am I just insane?