Whirlwind-rng

Cleanroom implementation of the whirlwind RNG.

This implementation follows the construction laid out in the original paper. However, this implementation deviates slightly from the paper in the following ways:

• Uses blake2b as the hash function
• Uses full hash output of blake2b in lieu of SHA-512 transform (h())
• Uses keyed blake2b for hash reseeding
• Requires the caller to provide an initialization seed ("IV")

This implementation uses an explicit state argument for every function. Thus, this is fully thread-safe.

The blake2b implementation is borrowed from libsodium.

Guide to Source

• whirlwind-rng.c: The implementation of Whirlwind RNG
• whirlwind-rng.h: Public interface to the implementation
• blake*: Blake2b implementation
• t-ww.c: Basic sanity test
• bench-ww.c: Simple benchmark test

Tests

bench-ww.c is a simple benchmark that prints the cost of adding entropy and generating random bytes of various sizes. Example usage:

bench-ww  4 8 16 32 64 128 256 512 1024

This will generate random bytes of 4, 8, 16 etc. bytes and show associated timing information in CPU cycles. On my Late 2013 Retina MacBook Pro (2.8GHz Core i7), the above invocation shows

   4,  151.0537 cy/add, 3160.2849 cy/byte, 12641.1394 cy/blk
   8,  168.7217 cy/add, 1769.0247 cy/byte, 14152.1978 cy/blk
  16,  155.4158 cy/add,  812.3566 cy/byte, 12997.7051 cy/blk
  32,  149.5706 cy/add,  379.3949 cy/byte, 12140.6355 cy/blk
  64,  164.0715 cy/add,  217.1170 cy/byte, 13895.4868 cy/blk
 128,  386.3782 cy/add,  122.8829 cy/byte, 15729.0155 cy/blk
 256,  196.8602 cy/add,   77.3959 cy/byte, 19813.3384 cy/blk
 512,  208.2917 cy/add,   56.1442 cy/byte, 28745.8385 cy/blk
1024,  190.6415 cy/add,   44.6681 cy/byte, 45740.1093 cy/blk

t-ww.c is a most basic sanity test. Ultimately, I hope to enhance this to generate outputs suitable for use in a statistical test-suite to measure randomness.