Alieniloquent

Quickly on the heels of the initial release of my Base32 library, I have an update. I should have tried to compile it on Linux, as the GCC settings on my Gentoo box caught some silly things I had done.

It’s all better now, and the gem can install on both Mac OS X and Gentoo Linux. I assume other Linuxes are probably fine, as are BSDs and other *NIXes.

To download it go here.

As you may know, I’ve been working with base32 encoding. Well, I decided to share my work with the world in the form of a library.

This first release simply contains the code I needed for my original project, but I’ve packaged it up as a nice Ruby extension.

You can visit the project page here.
You can download the release here.

I’ve scribbled this down so many times, I thought you all might want to benefit a little from my troubles.

|0000 0|000 11|11 111|1 2222| 2222 3|333 33|33 444|4 4444
|0000 0|111 11|22 222|3 3333| 4444 4|555 55|66 666|7 7777

That is a chart to help understand how five octets turn into eight base32-encoded bytes. It should be fairly self explanatory, but when I say that, I’m always wrong.

The top row is the octets. I’ve each group of four represents four bits, and the numbers represent which octet it is. The bottom row represents the quintets, with the same numbering scheme. I spaced the digits the same, so you can see how they match up. The pipes are nice visual borders.

So I’m writing the license-key generation code for the store-front for a shareware program my friend Tyler and I are preparing to release (more about that later). We’ve decided to use cryptography to reduce the likelihood that our licensing schema will be compromised (for relatively little effort on our part). We also decided to base32 encode the actual keys to make them easier to read.

Well, the store-front is going to be a Rails app, of course. Ruby has a module to base64 encode, but it doesn’t have one to base32 encode. So, I wrote one, and I did it test first (of course).

The first four tests were easy. Really short strings, but they worked out most of the kinks. But, I wanted something that would boost my confidence further. So I wrote the following test which ended up being quite patriotic.

def test_constitution_preamble
  plaintext =<<-EOT
    We the people of the United States, in order to form a more perfect union,
    establish justice, insure domestic tranquility, provide for the common
    defense, promote the general welfare, and secure the blessings of liberty
    to ourselves and our posterity, do ordain and establish this Constitution
    for the United States of America.
  EOT
  encoded = %W(
    EAQCAIBAEBLWKIDUNBSSA4DFN5YGYZJAN5TCA5DIMUQFK3TJORSWIICTORQXIZLTFQQGS3RA
    N5ZGIZLSEB2G6IDGN5ZG2IDBEBWW64TFEBYGK4TGMVRXIIDVNZUW63RMBIQCAIBAEAQGK43U
    MFRGY2LTNAQGU5LTORUWGZJMEBUW443VOJSSAZDPNVSXG5DJMMQHI4TBNZYXK2LMNF2HSLBA
    OBZG65TJMRSSAZTPOIQHI2DFEBRW63LNN5XAUIBAEAQCAIDEMVTGK3TTMUWCA4DSN5WW65DF
    EB2GQZJAM5SW4ZLSMFWCA53FNRTGC4TFFQQGC3TEEBZWKY3VOJSSA5DIMUQGE3DFONZWS3TH
    OMQG6ZRANRUWEZLSOR4QUIBAEAQCAIDUN4QG65LSONSWY5TFOMQGC3TEEBXXK4RAOBXXG5DF
    OJUXI6JMEBSG6IDPOJSGC2LOEBQW4ZBAMVZXIYLCNRUXG2BAORUGS4ZAINXW443UNF2HK5DJ
    N5XAUIBAEAQCAIDGN5ZCA5DIMUQFK3TJORSWIICTORQXIZLTEBXWMICBNVSXE2LDMEXAU===).join
  assert_equal(encoded, Base32.encode(plaintext))
end