How to actually decipher one of Blindspot's very difficult tattoo clues

On NBC’s new drama Blindspot, Jane Doe (Jaimie Alexander) was dosed with an experimental memory loss drug, covered in tattoos and left for the FBI to find naked in a bag in Times Square. Quickly in the pilot, one of Jane’s tattoos is easily deciphered, helping the FBI prevent a terrorist attack on Liberty Island. But decoding these tattoos, which the producers promised everyone could do at home, is not as easy as they make it seem. What follows is a real account of trying to do so:

Let’s go back to August when I spoke with executive producer Martin Gero: He provided clues on two of the upcoming tattoos. One of the tattoos that will be featured in the second episode include a set of numbers and letters that read 399/IHRTVLALVKBBHHJ/7, which was magically going to provide a person’s name.

Here’s exactly what Gero teased:

Easy, right? Wrong. Oh, so wrong. The tattoo in the pilot — Chinese lettering behind Jane’s ear — was solved by her literally translating the language — the Wenzhounese​ dialect, specifically — to the day’s date and a street address: 399 White Street, Apt. 7. You’ll notice a very glaring similarity between the tattoos from the pilot and episode 2: The numbers 399 and 7 bookend them, which tells us that they are connected somehow.

While rewatching the rest of the pilot, I realized that there’s no way I could actually decipher this based on what Gero had said — I clearly don’t know Wenzhounese​, which was needed to solve the clue in the pilot — which led me to drafting an email to Gero conceding defeat … until I got to the end of the episode and NBC literally spelled out the answer during the trailer for episode 2. Somehow 399/IHRTVLALVKBBHHJ/7 translates to MajArthurGibson. A quick search online provided me with the logline for Monday’s episode that, in part, says: “The team unlocks a cryptic tattoo that points to Major Arthur Gibson (guest star Robert Eli), an Air Force pilot with a painful past and a lethal agenda.”

But how, NBC? How did they get that answer?! I wouldn’t be swayed. Now I was even more determined to find out how they did it, even if I already knew the answer. My email to Gero changed:

Yes, I was initially determined to figure it out myself, but as you can see in my email, I was just desperate for answers. However, Gero wasn’t going to let me off that easy. By the by, in my imagination, Gero was sitting behind his computer screen, laughing that I could not solve his apparently easily solvable riddle, because I got a quick response:

I played it very cool (and not at all frustrated) in my response:

His response, as I’m sure he continued to laugh maniacally like an ’80s film villain. Kidding. Probably:

The next two hours were filled with internet searches of various ciphers and codes. I now know the basics of Caesarian shifts, Affine, Baconian, Keye Caesar and Columnar Transposition — though, really, I now know they exist. There was also one random cipher I kept seeing pop up, Vigenère, but it involved having a keyword, which I know I didn’t have, so I ruled it out immediately (and stupidly). Finally, I called it a night, firing off an email to Gero saying that I’d be back at it in the morning, so do not give me any more hints. Twirling his mustache, Gero responded:

On day 2, it was becoming silly that I hadn’t figured it out yet. With the cipher clue in hand, I valiantly … searched “Different types of ciphers.” Not kidding. I came across that Vigenère one again, which started to feel like a sign that I was overlooking something vital — which, in fact, I was. I did have a keyword staring right at me: White Street Apt. A very long, but 14-letter keyword. So I then popped this into a Vigenère cipher generator (What, I was tired! What if I was wrong?!) and the answer it spit out was correct: MajArthurGibson.

Because that was way too easy, I decided to actually learn how to decrypt and encrypt using the Vigenère cipher table, which looks like this:

First, you’ll want to write out your encrypted message on a line, like so:

Then, you write out your keyword below so the letters will correspond. In this case, the keyword is one letter shorter than the message, which means you would start the keyword over from the beginning, using the letter W twice. If the message was longer, you’d continue using the keyword over and over. Also, when using a keyword, you ignore spaces — which is what caused me to ignore White Street Apt. as a potential keyword.

In short, a message encrypted using the Vigenère cipher means each letter in the message is replaced by a letter some fixed number of positions down the alphabet. Unlike the Caesarian shift, which uses the same method, there is a different shift for each letter in the message, which is determined by the keyword. Let’s bring up that table again:

On the table, the vertical axis is the keyword, while the horizontal axis is the actual message. Using the table, you’d find the first letter of the keyword on the lefthand vertical side. In this case, it is W. Along the W axis, you’d go horizontally along that row until you hit the first letter of the encrypted message, which is I. Scrolling up to the top of the table, you’d see that corresponds to the letter M. Boom, you just figured out the first letter! Continue the process until you get the actual answer and feel like a genius … before realizing you already had the answer and probably would never have figured it out without it.

My final message to Gero, ultimately conceding defeat because, well, by even emailing Gero, I totally cheated the process:

In short, sad. Oh, so sad.

Blindspot airs Mondays at 10 p.m. ET on NBC.