Breaking with my usual style, Quick Project #2 doesn't necessarily relate to music programming.
Today I came across a nice little article and demo on r/compsci about timing attacks.
Timing attacks are something that I had learned about a few years ago but for whatever reason had dropped from the forefront of my engineering consciousness. In order to bash myself over the head with it (and provide a universal solution), I created Ruby wrapper methods for Object#send and block evaluation that are padded with a fixed timing delay.
Here 'tis, including some basic String comparison examples at the bottom:
https://gist.github.com/2554841
To use it, just pass in a "safe" duration (in seconds) that likely exceeds any possible amount of time it could take to evaluate the code. In the following example I use the greatly exaggerated value of .75 seconds. In the wild, you'll most likely be working in smaller durations
is_match = ExpressionTimer.block(0.75) { "password attempt!" == "my password!" }
When the example is run, no matter how quickly the block actually evaluates, it will always take exactly 3/4s of a second to return. As a result, actual timing information is lost in the ether and can not be gleaned by any outside observer.
As I get ready to move once again (this time to the Ridgewood/Bushwick border) there's not a whole lotta time for personal projects. Yesterday I decided that I would find a quick one and do it no matter how useless it was.
Turned out, I came up with something that's going to be pretty useful (for me). Last week, a coworker pointed me to marcel's awesome Ruby giftube script which extracts animated gifs from online videos. I've been looking to incorporate more audio samples in my music for quite some time, so I forked his script and changed it to extract audio samples instead of gifs, complete with mp3 conversion.
Here's the result:
Being on my way to the west coast and out of arm's reach of the synths, I've had a few hours to switch gears and put together a quick Ruby gem, MicroOSC. It's a utility and DSL for dealing with OSC messaging.
gem install micro-osc
I applied the same principle to OSC that I applied to MIDI with MicroMIDI: distilling the simplest messenger interface that I could think of.
Unlike MIDI, OSC deals with generic user-defined messages. This eliminates the need for describing different concrete message types, something that added a lot complexity to MicroMIDI.
MicroOSC can function as a server, a client or both. In this example, I'll demonstrate them separately, having the two programs talk to each other over a local network.
Here is a server:
require "osc"
OSC.using(:input_port => 8000) do
receive("/greeting") { |val| p "received #{val}" }
p "Ready to receive OSC messages on port(s) #{input_ports.join(', ')}..."
wait_for_input
end
Once you have this running, you should see "Ready to receive OSC messages..." in your Ruby console. Switch to another window and run this client program:
require "osc"
o = OSC.using(:output => { :host => "localhost", :port => 8000 })
o.out("/greeting", "hullo!")
After running it, flip back to your server program and see “received hullo!”, confirming that your two programs were in fact talking to each other!
Notice that in the second program I didn't use a Ruby block style. Doing it this way would generally be better for live coding, and probably some other scenarios as well.
That's it!
Look for another post with real-world examples, advanced techniques and combining with MicroMIDI soon.