This blog explores six pseudorandom number generators which are enumerated as follows:
Here is the order in terms of run-times from the fastest to the slowest: 1, 2, 3, 6, 5, 4.
The Advanced Encryption Standard (AES) is fully described in the National Institute of Standards and Technology (NIST) publication:
Click to access NIST.FIPS.197.pdf
AES is a secret key block cipher with a block length of 128-bits and variable key lengths of 128-bits, 192-bits, and 256-bits.
The ANSI X9.17 pseudorandom number generator is described by Alfred J. Menezes, ET AL. in the Handbook of Applied Cryptography on page 176 5.11 Algorithm.
We use triple-AES with three 256-bit keys in Encryption-Decryption-Encryption mode. Also we utilize two 128-bit numbers. The total key space is (768 + 256)-bits = 1024-bits.
We now illustrate in the following screenshots our C# implementation of a stream cipher using the preceding algorithms.
We use the following dialog to allow under certain circumstances the application to randomly generate the seed material for our PRNG. Unfortunately, the built-in C# PRNG only has 2^31 -1 = 2147483647 different seeds. This cuts down on the amount of thought and typing required but is inherently dangerous due to the relatively small number of seeds. If you want true security the requisite sixteen 64-bit numbers must be random.
Optimally we would like to 0 index of coincidence, but 0.00222 is reasonably acceptable.
Numerical Explorations 