This week's puzzle on themastertheorem.com
was easy, though one of the words in the solution was created specifically for this puzzle. I hate it when this is done; it makes it harder to be sure you've solved the puzzle correctly.
Despite this, the puzzle was pretty easy. A classical four-square encryption, and the keys were provided in the article text.
Having worked through 30 of the puzzles so far, I decided to write a library in Retro to deal with encryption and decryption using the classical techniques M likes. I have a few (ceaser, rot13, pigpen, tapcode) done, and a couple more (keyword, four-square) nearing completion. This should make future puzzles more straightforward.