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Frosty Keypad

Table of Contents

Overview

Up towards the castle off to the right is Morcel Nougat standing next to the Frosty Keypad.

He is stuck and needs help.

Introduction

Morcel Nougat

Hello again! I'm Morcel Nougat, dashing around like a reindeer on a sugar rush! We've got a bit of a dilemma, and I could really use your expertise.

Wombley and Alabaster have taken charge now that Santa's gone missing, and We're scrambling to get the Wish List secured. But… one of the elves in the Data Management Team got overzealous, and the Shredder McShreddin 9000 gobbled up a crucial document we need to access Santa's chest!

It's our golden ticket to getting Santa's Little Helper tool working properly. Without it, the hardware hack we're planning is as empty as Santa's sleigh in January.

Think you can help? I can get you into the Shredder McShreddin 9000's inner workings to retrieve the pieces, but there are two access codes involved. One of the elves left a hint, but it's all a blur to me!

I've noticed that some elves keep referring to a certain book when they walk by. I bet it has the answers we need to crack the code and recover the document!

You know, some of the elves always have their noses in the same book when they pass by here. Maybe it's got the clues we need to crack the code?

Hints

Hint 1: Just Some Light Reading

See if you can find a copy of that book everyone seems to be reading these days. I thought I saw somebody drop one close by…

Hint 2: Shine Some Light on It

Well this is puzzling. I wonder if Santa has a separate code. Bet that would cast some light on the problem. I know this is a stretch…but…what if you had one of those fancy UV lights to look at the fingerprints on the keypad? That might at least limit the possible digits being used…

Hint 3: Who Are You Calling a Dorf?

Hmmmm. I know I have seen Santa and the other elves use this keypad. I wonder what it contains. I bet whatever is in there is a National Treasure!

Items

Walking around the yard you can find two items: a notebook and a UV flashlight.

Notebook Pages

FrostyBook-1.png

FrostyBook-2.png

FrostyBook-3.png

FrostyBook-4.png

FrostyBook-5.png

FrostyBook-6.png

FrostyBook-7.png

Keypad

The challenge presents a keypad with a note attached.

keypad.png

note.png

Silver

Analysis - Book Cipher

One of the hints refers to the 2004 film National Treasure, where the Ottendorf Cipher is a key plot device found on the back of the Declaration of Independence, revealed via heat and lemon juice.

The Ottendorf Cipher is a type of book cipher where plaintext is encrypted into sets of three numbers, typically indicating a specific page, line, and word (or letter) within a pre-agreed text, such as a book, newspaper, or document. The receiver must possess the exact same "key" text to decode the message.

In this challenge, the Ottendorf Cipher is using page:word:letter. After checking the pages in the notebook, we get the following results.

Location Result
2:6:1 S
4:19:3 A
6:1:1 N
3:10:4 T
14:8:3 A

To convert the letters into numbers, let's use the telephone keypads used in older telephones where letters where mapped to a number.

telephone-keypad.png

Letter Number
S 7
A 2
N 6
T 8
A 2

Silver Solution

The code for the keypad is 72682.

Gold

WOW, you did it! You know, they say Ottendorf ciphers were used back in the Frosty Archives crisis… or was that during the Jack Frost incident? Either way, you're amazing!

But wait—there's still one more code tucked away! This one might need a bit more elbow grease… you may need to try a few combinations to crack it!

Analysis - Brute Force

Using the UV flashlight, you can see that the keys 2, 6, 7, 8, and Enter have fingerprints on them. The other keys do not.

The challenge makes it clear there are two different codes.

The UV flashlight highlights four (4) of the same digits from the first code. It's worth a try to brute force it. Let's start with the assumption that the second code is the same length as the first code, i.e., five numbers. Hence, the fifth value has to be one of the four digits 2, 6, 7 or 8.

Let's write a Python script frostykeypad.py to try all possible combinations from these four digits. The itertools Python library will take a list of things and a length and generate all possible lists of that length, allowing repeats.

The total number of iterations will be: $\(\text{NumOptions} ^ \text{Length} = 4^5 = 1024\)$

Initial tests shows the following rate limiting error: 

22222 400 {'error': "The data you've provided seems to have gone on a whimsical adventure, losing all sense of order and coherence!"}
22227 400 {'error': "The data you've provided seems to have gone on a whimsical adventure, losing all sense of order and coherence!"}
22226 429 {'error': 'Too many requests from this User-Agent. Limited to 1 requests per 1 seconds.'}

When sending a request, the browser automatically adds a user agent to every request using the User-Agent: header. This header contains information about what is sending the request. In the case of Chrome, it will contain that it's Chrome and which specific version of it is running.

To circumvent this limit, we can try modifying the User-Agent on every request. This way, we should never hit a limit. To do this, we can set the User-Agent to something that includes the answer. This will make sure we can never send the same User-Agent twice. For example, 

headers={
    "User-Agent": f"somerandomstring{code}",
},

Note, however, that adding delay of one second using the sleep function will take at most 1024 / 60 ~= 17 minutes. We can set the User-Agent header to something unique per request to avoid rate limiting, but for now, we'll just wait between requests.

Since we now that there are two possible codes, we will not break when we find a valid one.

Gold Solution

Running the Python script provides the following output: 

python3 frostykeypad.py

Success: 72682
..........................................
Success: 22786
............

The second code for the keypad is 22786.

Outro

Morcel Nougat

WOW, you did it! You know, they say Ottendorf ciphers were used back in the Frosty Archives crisis… or was that during the Jack Frost incident? Either way, you're amazing!

Unbelievable! You found a flaw in the system and completely bypassed the rate limiter. You're practically an elf legend!

Incredible work! You pieced together the code like a true sleuth and retrieved the shreds we need. I'm not quite sure how you'll put them all together, but if anyone can, it's you!

Your help has been absolutely essential, especially now with Santa missing. Wombley and Alabaster will want to hear all about it—go share the news with Jewel Loggins!

More Items

He also gives me one thousand little teeny tiny shredded pieces of paper.

This will be useful for the hardware challenges.

Files

File Description
frostykeypad.py Python brute-force script using itertools.permutations and curl
FrostyBook-1.png through FrostyBook-7.png Notebook pages used for the Ottendorf cipher
keypad.png The keypad with note and the fingerprints shown with the UV light
note.png The note attached to the keypad with the book cipher locations
telephonekeypad.png A telephone keypad with the mapping between letters and numbers

References
← cURLing Hardware Part I →