Challenge Four Solution

Well, how did you get on? It seems a long time since we last spoke, and I guess you guys have had a vacation, but frim the looks of things you were pretty busy. You can view the solution to Challenge 4 in Aggie's Journal.

Aggie hit on the idea of a keyword cipher this time. using the keyphrase BABYLONSTONE. Strking out duplicate letters this becomes BAYLONSTE and continuing the alphabet from F gives an encryption scheme of BAYLONSTEFGHIJKMPQRUVWXZCD, i.e., a is encrypted as B, b as A, c as Y and so on. As usual frequency analysis gives the game away. E only appeared 7 percent of the time so we can assume some kind of subsitution is taking place, and with O appearing 11 percent f the time its a fair guess that it substitutes for e.

Several of you were tripped up or confused by the phrase "m will" in the text. Some of you even came up with fancy theories about it like, "Since m should be encrypted by I perhaps it shold have read "i will", but the truth is much simpler. M is an initial. Remeber this is a journal and people often use abbreviations when writing down their secret thoughts.

Winners and the Hall of fame to be announced later today, and the next challenge goes up at 4pm. As usual the site will be down for maintenance for a little while beforehand.