# Solving Decred’s “Autonomy” puzzle

May 8, 2017 · 7 min read

The Decred Puzzle Team’s third puzzle kicked off on April 25th with a tweet and a mechanical vibe:

The puzzle, “Autonomy”, was created by coin_artist, along with collaborator zden/satori and illustrator Diego Rodriguez.

Going to the puzzle link reveals an 82MB highly-rendered, photorealistic gate with an assortment of gears.

https://decred.org/autonomy_puzzle/img/gateHQ.png

Below that, we see some sort of a timer counting down, and below that, an animated gif with a television looping through a series of images.

Underneath the GIF is a text entry box, and a button underneath to submit the form that says “I know it”.

The television is showing the story of DCR and PoS.

• 5 tickets are chosen randomly from the pool
• If at least 3 of them vote ‘yes’
• The proof of work is validated
• The miners are compensated
• The transaction clears
• (Silence ensues)

The flashing light on top of the television is a binary transmission. The GIF has 128 frames, so if we extract and convert to binary, we get:

`01000011 01001111 01010010 01000101 00100000 01010100 01001111 01001111 00100000 01010000 01000001 01001001 01001110 01000101 01000100`

Run this through a binary->ASCII converter and we get

`CORE TOO PAINED`

OK, that’s got to be something. But it doesn’t do anything when you put in in the entry box. Maybe it’s an anagram.

`OPERATION CODES`

Oh, OP_CODES! OK, let’s head over to the list of opcodes in Decred!

There are 6 Decred-specific opcodes.

`OP_SSTX                = 0xba // 186 DECRED OP_SSGEN               = 0xbb // 187 DECRED OP_SSRTX               = 0xbc // 188 DECRED OP_SSTXCHANGE          = 0xbd // 189 DECRED OP_CHECKSIGALT         = 0xbe // 190 DECRED OP_CHECKSIGALTVERIFY   = 0xbf // 191 DECRED`

Let’s start entering them, shall we?

`OP_SSTX`

Cool, that worked! A gear appears above the entry box. (with a Roman numeral II marked on it)

Also, the sequence of images on the TV seems to have changed. Now it is showing the original sequence plus the process of a ticket being revoked.

`OP_SSRTX`

That did something — Another gear appeared! (marked I)

And the sequence of images on the TV changed again. Now it displays a ticket purchase and a successful ticket voting process.

`OP_SSGEN`

Another gear!

At this point the whole TV image disappears. We are left with the wall of gears, the 3 individual gears that have appeared, the entry box and the “I know it” button.

At this point, players were stuck for a looong time. People tried many things including Enigma, spiral ciphers, and looking for hidden data or symbols in the gear image. It was generally agreed that the gears went into the “gate” in the following order, from top to bottom:

II I III

This corresponded to the order in which they appear when you discover them, as well as their appearance relative to the rest of the gate image in terms of texture and shadow angle.

The solution is to measure the diameter of each gear’s cam shaft in pixels. Dividing each of these diameters by 10 yields a sequence of steps. You must move through the gears, turning each one counterclockwise by the number of steps specified by it’s cam shaft.

Here is Zden’s original design doc for the Wheels Puzzle:

Reading the tooth which connects to the next gear, and switching letter wheels as you pass each one, yields a phrase: (h/t to @bdub77)

`ED ENTREE FORTIFY MORROW`

Enter this and you’re on to the next phase of the puzzle:

https://decred.org/autonomy_puzzle/img/0lZJBnN0iSJ4CaNEHEcsnvN3QDsN4FcaF4SsxgWBjxbjHrzeik6fG6LqMjrTxYIx.mp4

-Satoshi Nakamoto. Hmm, this appears to be a Satoshi quote.

The strings each seem to be mirrored, and consist of

• a symbol,
• 4 letters of Morse code,
• and a compass direction.

Decoding and compiling all the strings yields a large table of information.

But after much analysis, nothing seems to be getting us through to the next phase.

Let’s go back to the answer we got in the last step:

`ED ENTREE FORTIFY MORROW`

It’s kind of weird — what if it’s an anagram?

Aha!

`NEW TERRITORY OF FREEDOM`

That sounds like something Satoshi might say! If we Google it… yep…

A new territory of freedom! Nice!

Enter NEW TERRITORY OF FREEDOM in the box, and we’re transported to an epic chase scene, with Decred Girl running down a stone hallway, being chased by a 3-headed Hydra and what appear to be robot aliens, while carrying an illuminated baton.

On the wall to her left, there is a grid of symbols. They correspond to the pieces that were discovered during the video puzzle.

Presumably this is some kind of map for the text segments from the previous step . Laying out the letters in the order listed in the 5x5 matrix renders nothing recognizable, though.

What about the compass directions? We haven’t used them yet — What if they tell us how to move through the matrix?

Let’s sort them by the order in which they emanated from the portal in the video. Starting at the center of the 5x5 grid and walking stepwise along the path set out by the compass directions gives us the following sequence.

If we follow the path and use that to order the sequences, we end up with groupings that look like this:

`M SA LLAYODB OF EETDNMIRSD EIIRPFS TDREI BY UN AEQUNACHN LEBTAIFN IHETH MR IISSICN OAN ARTELETH UCO  SERHF OSTI.Y R`

Hmm. OK. If we rearrange the letters in each of the 4-letter segments, we arrive at:

`A SMALL BODY OF DETERMINED SPIRITS FIRED BY AN UNQUENCHABLE FAITH IN THEIR MISSION CAN ALTER THE COURSE OF HISTORY.`

-Ghandi! (h/t to OhGodAGirl for discovering this quote.)

Let’s enter it into the box.

Hmm, no luck.

Players kind of flailed here for a while. The quote from Ghandi had to be the right direction. But it wasn’t getting anyone to the next level. Then, someone realized you had to enter it like this, with a space before the period:

`A SMALL BODY OF DETERMINED SPIRITS FIRED BY AN UNQUENCHABLE FAITH IN THEIR MISSION CAN ALTER THE COURSE OF HISTORY .`

This way you use all 116 (29 * 4) characters, including the final space.

Kind of odd, but it worked! We’re on to the next stage!

The following text appeared below the chase scene. This was exciting. 259 characters. This could easily be the 33-word wallet recovery seed.

`uheeecfphjznrrvvleiqifgbxfvxfyniepfuoeefuhwnvpoomehketylatyvikudwmxguqtcizgivkmvgsxfewoahowkmjloooaaabfdkczqxntiawgyqakmiaxaxtrrghyliyfjirgwtossiriaiomexkvcewmfzqrrcwnycxfzkaldimzfigxtifwcxqlwphplekdrswvwxrkqvpigagmtbbgsdzpobeezcphianxldxppqivzkqfmvvbzavtsvxb`

It seemed that this had to be the wallet seed with some sort of cipher or encoding applied. After a few different approaches, we tried attacking it with a Vigenère Cipher. First we tried using single known plaintext words from the PGP word list, but that wasn’t enough to sufficiently narrow down the possibilities.

Then we tried using the “small body of determined spirits” quote from the previous step as the cipher key. The output was a single result.

`upsetrebellioncrusadecomponentframeworksensationbackwardnarrativeupshotpioneerfreedomsavagerysnowcapparamountuprootuniverseislandgalvestontumorhemispheredrunkenhideawayrebirthbusinessmandogsledheadwaterssentencedirectionvillagemicrowavedwellingdistortionbanjo`

My heart started racing. This was intelligible... “banjo”… is that in the PGP wordlist? Yup! Quickly counting the words... 33. This is it! Time to add in spaces where they should appear:

`upset rebellion crusade component framework sensation backward narrative upshot pioneer freedom savagery snowcap paramount uproot universe island galveston tumor hemisphere drunken hideaway rebirth businessman dogsled headwaters sentence direction village microwaved welling distortion banjo`

Galveston — is a proper noun. We need to capitalize it.

`upset rebellion crusade component framework sensation backward narrative upshot pioneer freedom savagery snowcap paramount uproot universe island Galveston tumor hemisphere drunken hideaway rebirth businessman dogsled headwaters sentence direction village microwaved welling distortion banjo`

It worked!

Thanks to @coin_artist and the whole Decred puzzle team (Zden/Satori, @coin_artist, Diego Rodriguez, Dyrk) for this amazing, maddening and addictive puzzle!

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## shellcoding 101 — RPISEC/MBE/lab3C

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