Think of a CSPRNG as encrypting a simple incrementing counter with, say, AES using a random key (this is in fact one of the ways you can build a CSPRNG). A CSPRNG function that&#x27;s not weak is basically equivalent in strength that has n bits of entropy is then basically equivalent to a cipher with that many bits of key.<p>The acceptable safe maximum length isn&#x27;t quite infinite, it&#x27;s basically 2^64 rounds (not necessarily bits or bytes) for 128 bits of entropy. But that&#x27;s basically arbitrarily long in practice as anyone cares.