Meet Tim Johnson, Who Solved "The Mystery of the Old Postcard" — and He Tells Us How
Last week, after I posted the solution to “The Mystery of the Old Postcard,” I got an email from the detective himself, Tim Johnson. Here’s what he said about himself:
“Hey there, I'm the one who got the postcard figured out. My dad is also named Tim Johnson with a different middle name, so we're not Sr./Jr. He saw the postcard on the "You're probably from Memphis If…" Facebook group and asked me if I could figure it out. I'm not good at describing myself, but I'm 30 years old; we've lived in eastern Kentucky since 1998. I graduated from Eastern Kentucky University in 2010. I was working on a degree in Computer Science with a minor in Philosophy, but then switched to General Studies later because of the math. I work at EKU now handling their video teleconferencing stuff.
"Computer science classes involve encryption, and this kind of code is the type of thing we learned about in the history part of some security classes. Caesar used a type of substitution code, for example. So this was like a first-week introductory to cryptography kind of problem. If this used even medieval-era cryptography then I'd probably be stumped."
So that’s Tim. Then he explained how simple it was to solve the coded message on the postcard. Simple? Well, I'd better let him explain it:
"Here's how I got it figured out. First, I made a guess that it's a substitute system. If this was a letter going across enemy lines during a war then this would be a bad assumption, but for friends across town it's probably not a complicated system. It's probably only encrypted so that the mailman or their mom won't read the message. Next, I made a list of what I figured are letters. I was wrong about some of them, because for example there are 2 that look like pi, and also some dots are parts of other signs, and some dots are their own letter, so I did kind of bad at that. I figured having something that I'm able to type would be good to start off with and easier to analyze, so I took the list, and I assigned a letter to each one, like this:
E = a
c = b
[ = c
; = d
+ = e
pi = f
* = g
0 = h
triangle = i
( = j, and so on.
Then I typed up the letter using my new letters that I substituted in. I put question marks where that scribble was at:
"If I was right about guessing that it was just plain substitutes and that it was written in English and everything, then you can start off by finding which characters happen the most, and which ones are paired up, things like that. Q usually has a U come after it, TH is paired up a lot, OO, EE, TH, etc. I know from Wheel of Fortune that RSTLNE are popular letters. It turned out that this message doesn't have an S, so statistics aren't a strict rule.
"So I looked on Google to see if anyone had an article about statistics like that, or a program that would analyze a block of text and tell you which are probably vowels or some hint like that, and I searched Google for "substitution cipher solver." The first result is a web page that not only gives statistics but makes guesses, which is more than I'd hoped for. I pasted that block of text earlier into it and clicked Solve.
"It has a long list of guesses, and one that looked promising is this:
"dear pooher woe nare chov s ghoing to write to an old are driend hoow???ch ours moto er and gatoerhoo he chous are all well and oawing a good time"
"Looking at the address half of the postcard, it mentions Cooper as a name, and it makes sense for a letter to start with "Dear (name)" so I found the first repeating characters, figured they must be OO, and the ones in front of that are DEARC. I printed out a copy of the letter, and wrote O under all the pi's, E under all the c's, A under the ['s, R under the semicolons, etc. Then it was kind of like Wheel of Fortune guessing what fits in the rest of it, plus that web site has quite a few guesses to choose from. OAWING A GOOD TIME, DO A FING A GOOD TIME were at the end, and I eventually figured out that some of the places where I had written an O under the pi, it'd make more sense to have an H, like HAVING A GOOD TIME. Also MOTHER in a letter makes more sense than MOTOER. I noticed some had a round top, and some had a flat top, and if I changed all the flat-topped ones to H then other stuff got easier and made some sense. Eventually I got the whole thing filled out like that.
"For the bottom line, the middle one that looks like a 7 looks the same as the M in mother. The last character that looks like a lower-case e with a dot looks the same as the G in good (good is the last 4 characters of the 9th line), except that one is connected and the other isn't, but that could just be a handwriting thing. There aren't any other #'s throughout the message, so it could be a letter that isn't used in the message like a Z or something, so the letter would be signed by from someone with the initials ?MG. Or, the # could indicate 'number', and it means that this is the number you use to decrypt it. They could have a list that they've shared ahead of time, where 7e means you turn the Little Orphan Annie secret decoder X many clicks. If that's the case, then the next postcard might have a totally different alphabet."
Got that? Okay, now why don't you explain it to me? Whew! Thanks, Tim. Where would we have been without you (and Wheel of Fortune)?