Open Source Computing

Week 4


Plans for teams

We will use Daniel Bernstein's ChaCha cipher as a random-number generator. See https://cr.yp.to/chacha/chacha-20080120.pdf.

ChaCha achieves cryptographic mixing through additions, xors and shifts. No multiplications or divisions are used.

echo "hello and welcome to Open Source" | shasum -a 512

python3
import numpy as np
from randomgen import ChaCha
seed=0x1234567
rg=np.random.Generator(ChaCha(seed, rounds=20))    # use the seed from above
# now rg.integers(A,B) chooses a good random value between A and B-1, inclusive


Monday 9/15: licenses.html, "Speaking of SFC" note about Bradley Kuhn


Calculator

Open Source as a business

    "Open Core"

Linux history

What made Linux such a successful open-source project? Why did Linux beat BSD?
The email from Linus Torvalds to Mauro Carvalho illustrates two things:
  1. Torvalds' somewhat abusive style
  2. Torvalds' firm no-regression policy: user code that used to work should never be broken by a kernel update.

How do these factors play out in the success of Linux?

A third factor is Torvalds' policy on contributions: all are welcome, but they start out as non-mainline extensions, patches or modules.

386BSD

LibreOffice, bash