⇥ Challenge #3 beaten!

As predicted, someone came up with a solution to Challenge #3 in no more than a few hours. In fact, ten people came up with a solution as of tonight—and the first one came in a mere 90 minutes after I posted it, so either it was really easy, or I’m dealing with some smart folks

The riddle was generated using a simple algorithm: the alphabetical position of each letter of the cleartext phrase was added to consecutive prime numbers of increasing value (i.e.: 2, 3, 5, 7, 11, 13, etc.). The result was then modulo 26′d and converted back into a letter.

Once the algorithm is reversed, the encrypted phrase is rendered back into the cleartext, which is “THE ABOMINABLE SNOW RABBIT”. In case you’re wondering, The Abominable Snow Rabbit is the title of a 1961 Warner Bros. short that my kids were watching last night as I was coming up with this challenge. The second clue was a reference to a post on my Twitter timeline, which referred to the fact that I had just composed a database of the first 100,000,000 prime numbers (an exercise for this Saturday’s presentation at DPHP)—a clear clue to the solution.

The challenge was complicated by two factors. First, a lot of people think that the number 1 is prime, which is not the case—I thought this might confuse some folks. The second is that the sequence of primes does not reset moving from the key to the encrypted text—and this did trip some people.

In any case, Edward Z. Yang came up with the solution first (after barely 1.5 hours!), and to him goes the winning prize.

Well, until next time—I’ll go back to thinking up some new challenge.