Maximum security strength in bits of ISAAC cipher? Wikipedia claims key length can be very big in this cipher, so I assume it can offer a million bits of security provided entropy of key is the same?

Of course I can SHA-256 hash the key to allow any key sizes for AES... but it defeats the whole purpose of having such large entropy when the security is less.

So what is the maximum level? For instance, AES-256 provides a 256 bit security level.
I don't want it to wrap the keys or diminish its security/entropy.

Wikipedia and most sources are not clear about it.
ISAAC's internal state is a 256-element array of 32-bit words, so the maximum key size is 8192 bits. In theory, this means ISAAC has a maximum keyspace of 28192. It's important to remember, though, that attacks are known that can result from weak states, meaning not all keys are created equal. While this may not be an issue in practice, there are two primary reasons why you shouldn't use it:

It's not particularly well-researched, so more serious attacks may be lurking.

The entire 8192-bit keyspace is utterly unnecessary. 256 is more than enough.


Just stick with 256-bit AES if you need a block cipher, and ChaCha20 if you need a stream cipher.