Well, 337 isn’t a good number to deal with it. It’s kinda clumsy, because it’s a prime, it doesn’t have any factors. It can’t be divided in bytes (groups of 8 bits) or group of any size. So, there must be some slack bits somewhere.

Let’s get back to the frames. There are some frames at start and end of the animation that has the Decred logo and no bat-signal. Are they part of the binary data information or just noise? There are 6 at start and 7 at end. If we remove then, the number of bits goes down to 324, and it is a excellent number to work with, because it has many factors! So, binary data became:

010101010101010101011110111010101100001001101110110011000010001101110010011100001001100011000101110111100000010100101111001111011110001000101000010001110110111111001100101100101000011000011110110011000111001000101110001100100101010011010011011011110000011111111000010011001001111111101100000101011100011111000000000000000000

But it still cannot be divided by 8 (would remain 4 bits). So, we need to divide it by which number?

Take a look at the zeros at the end. There are 18 zeros there. And you know the relation between 18 and 324? 324 = 18². Yes, this binary information is a square!

Let’s reorganize it in a perfect 18x18 matrix:

010101010101010101

011110111010101100

001001101110110011

000010001101110010

011100001001100011

000101110111100000

010100101111001111

011110001000101000

010001110110111111

001100101100101000

011000011110110011

000111001000101110

001100100101010011

010011011011110000

011111111000010011

001001111111101100

000101011100011111

000000000000000000

Can you see the patterns emerging? Take a look again:

010101010101010101

011110111010101100

001001101110110011

000010001101110010

011100001001100011

000101110111100000

010100101111001111

011110001000101000

010001110110111111

001100101100101000

011000011110110011

000111001000101110

001100100101010011

010011011011110000

011111111000010011

001001111111101100

000101011100011111

000000000000000000

Would it be just a coincidence? Nope! This is a Data Matrix, a two-dimensional barcode consisting of black and white pixels. You must have seen it before, on a sticker on some electronic device.

So, let’s create a image and scan it!

For this step you can open any image tool and create the pixels one by one, or maybe just print it and cover the number with some pen but, yes, I’m lazy and my PC is fast:

Python is the best programming language ever.

This program (or your work) would create an image like this:

Now, just scan it with some app on your smartphone (or use a online tool like this excellent decoder) and you will get this:

Finally, we have some plaintext information!

37.790029, -122.40084

This is a GPS coordinate from San Francisco. Ok, now we know where Decred is going to! This is a GPS coordinate to Coinbase headquarters.

AND, it is also the password for 533d.7z file!

$ 7z x 533d.7z 7-Zip [64] 16.02 : Copyright (c) 1999-2016 Igor Pavlov : 2016-05-21

p7zip Version 16.02 Scanning the drive for archives:

1 file, 726 bytes (1 KiB) Extracting archive: 533d.7z

--

Path = 533d.7z

Type = 7z

Physical Size = 726

Headers Size = 134

Method = LZMA:16 7zAES

Solid = -

Blocks = 1 Enter password (will not be echoed):

Everything is Ok Size: 1088

Compressed: 726

Nice! Well, so, inside it must be the seed for the wallet with the prize, right?

Wrong.

seed.rtf

There are 33 words, obviously a wallet seed. But it is ciphered. I first tried a monoalphabetic cipher, rotating letters by one, but it doesn’t work. So, it must be a harder cipher. I think it is Vigenère Cipher. Lets use DCODE, a great online decoder to break it:

Well, it need more info to decrypt it. One know atack to Vigenère Cipher is the Known-plaintext Attack, when the cryptanalyst knows some piece of information from the original text.

But does we know any of those words? Yes! We know all of them! They are listed in this Decred Wallet’s source file:

There are 512 words on that list. But which one can we pick? Take a look again at the highlighted ciphered word Biig . It is a 4 letter word, beginning with a capitalized one. Looking through the mnemonics wordlist, this word could be Ohio . Let’s try it:

Vigenère code broke! The password is COINBASE. Lets decrypt it:

Finally, the wallet seed! Let’s try it on https://wallet.decred.org/:

And there’s the prize!