Fortuna is built on top of an underlying block cipher in counter mode (typically AES), with some additional machinery for periodic reseeding to recover from the situation where the PRNG's internal state is compromised at a particular point in time.
But in most cases, the correct answer is to use your OS's /dev/urandom (CryptGenRandom on windows). If that is not secure your app is probably screwed whatever you do.
Fortuna is built on top of an underlying block cipher in counter mode (typically AES), with some additional machinery for periodic reseeding to recover from the situation where the PRNG's internal state is compromised at a particular point in time.
But in most cases, the correct answer is to use your OS's /dev/urandom (CryptGenRandom on windows). If that is not secure your app is probably screwed whatever you do.