I am reading "Serious cryptography" and he wrote the following:
Informational security is based not on how hard it is to break a cipher, but whether it’s conceivable to break it at all. A cipher is informationally secure only if, even given unlimited computation time and memory, it cannot be broken. Even if a successful attack on a cipher would take trillions of years, such a cipher is informationally insecure.
Then, he proceeded to write that the one-time pad is informationally secure.
I don't understand this at all. If we see a cyphertext, such as
00110, we know that the corresponding plaintext has 5 bits as well, and the cypher key will also have 5 bits, thus
2^5*2^5=1024 possible combinations. Bruteforcing
1024 will yield a result. Even if the cyphertext is huge and bruteforcing won't be practical, it is still theoretical possible, no?
If it is theoretical possible, wouldn't it deem the one-time pad as informationally insecure?
What am I missing here?