A didactic and minimal implementation of the Fortuna cryptographically secure pseudorandom number generator.

$ pip install .
$ python example.py
(fortuna)
(fortuna) help

Documented commands (type help <topic>):
========================================
add_entropy  help  random

Undocumented commands:
======================
EOF  print_pools  print_seed_file  update_seed_file

(fortuna) random

In your terminal, colored traces will be displayed:

The example has only been tested on Linux, but it should work on macOS as well.

If you are only interested in the cryptography, the business logic is implemented in fortuna/__init__.py and fortuna/generator.py. The rest is for pretty logging purposes.

Specification

• https://en.wikipedia.org/wiki/Fortuna_(PRNG)
• https://www.schneier.com/academic/paperfiles/fortuna.pdf This is a chapter that is part of the book Cryptography Engineering. The previous chapters will help you understand this one.

Other implementations

• https://github.com/otms61/fortuna The base of this project but it seems unmaintained.
• https://github.com/seehuhn/fortuna
  • Interface for entropy sources is easier for user/application.
• pycrypto/Fortuna
  • pycrypto/lib/Crypto/Random/Fortuna/
    • FortunaAccumulator.py
    • FortunaGenerator.py
    • SHAd256.py
  • SelfTest/Random/Fortuna
    • test_FortunaAccumulator.py
    • test_FortunaGenerator.py
    • test_SHAd256.py
• https://github.com/freebsd/freebsd-src/blob/main/sys/dev/random/fortuna.c