Fortuna (Prng) (Paperback)

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Fortuna is a cryptographically secure pseudorandom number generator devised by Bruce Schneier and Niels Ferguson. It is named after Fortuna, the Roman goddess of chance. The generator is based on any good block cipher. Practical Cryptography suggests AES, Serpent or Twofish. The basic idea is to run the cipher in counter mode, encrypting successive values of an incrementing counter. On its own, this would produce statistically identifiable deviations from randomness; for instance, generating 265 genuinely random 128-bit blocks would produce on average about one pair of identical blocks, but there are no repeated blocks at all among the first 2128 produced by a 128-bit cipher in counter mode.