Numbers Stations – A Puzzle!
As a throwback to the Cold War-era of encrypted messaging, I tried my hand at using a One-Time Pad to encrypt a message to a friend. While you can use One-Time Pads in many different ways for theoretically uncrackable encryption, Numbers Stations are particularly relevant in a world where online activity can be traced. Numbers Stations use Shortwave Radio (read: radio signals capable of cross-continental transmission). If you are able to use a One-Time Pad correctly, and also transmit Shortwave Radio waves from variable secret locations, you could (in theory) be able to send 100% secure and untraceable messages. Imagine a spy receiving completely secure messages from their handler.
Important Vocabulary (in context of the One-Time Pad):
- Plaintext – The message that you want to send
- Key – The random list of characters characters used to encrypt a message (also referred to as the One-Time Pad)
- Cipher – The algorithm used to encrypt the plaintext with the key
- Ciphertext – The result of encrypting the plaintext with the key using a cipher
Some simple requirements for using a One-Time Pad and a Numbers Station to send a message to your spy:
- A purely random One-Time Pad shared by both the sender and the receiver
- A designated way to encode letters and numbers (and other syntax) that is understood by both the sender and the receiver
- A designated way to encrypt and decrypt the message with the key
- A Shortwave Radio transceiver for both the sender and the receiver
- Either a Morse Code oscillator or a voice to express the ciphertext over the radio
- A means for the receiver to write down or otherwise record the message
If your spy is undercover for a long time, you may find it difficult to use a One-Time Pad because your key will eventually run out of characters. Once you reach the end of your One-Time Pad, destroy it immediately. Reusing your One-Time Pad makes the encryption crackable, and not destroying it only makes your past messages vulnerable in the event that the pad falls into the wrong hands. If you reach the end of your key and you still wish to send messages, you must find a way to securely send a new key to your spy, and this could prove to be difficult in itself. Also, do not disclose your One-Time Pad to the world like I have done below. It’s meant to be a secret!
Since I do not own a Shortwave Radio transceiver, and I appreciate the reusability for the sake of a blog post like this, I created an MP3 file with the ciphertext. With credit to The Conet Project and http://imtranslator.net, this MP3 includes a computer voice speaking the ciphertext in French, wrapped with the infamous Swedish Rhapsody station‘s trademark song. For simplicity, my One-Time Pad includes only numbers. You might need to brush up on your French to decrypt it!
Ciphertext in MP3 format:
Encoding method:
One-Time Pad:
79175 94155 03846
49127 46850 18644
38965 71466 50120
91848 40444 54631
28666 04414 97244
92802 67043 05108
67323 39258 62002
03306 01632 16470
36453 85647 14728
97964 87619 45151
91537 14527 43709
72963 48386 27004
32408 30507 69824
23659 82490 30312
32841 86355 11436
16511 36783 91355
75720 81192 04549
16420 56400 81753
30824 30365 41070
68848 35885 08876
93598 84606 09426
27943 21054 30098
36904 91114 76838
60020 77799 43539
67408 41488 95494
88663 27054 80315
87088 57690 01917
76930 89852 28280
53360 05507 50717
18597 09767 26258
42080 27613 11524
59673 14588 23793
91224 91432 04180
27983 95220 17825
Your Call Sign is 206. Use the One-Time Pad and modular addition (modulus 10) to decrypt the message!
(Hint: the call sign is recited 3 times at the beginning, and the first 5 digits following that are a pointer to where in the One-Time Pad you should begin. Start decrypting with the block following the pointer!)
Once you have the plaintext, head to the following page and type in the code as the password in ALL UPPERCASE:
https://www.connor-mason.com/puzzle/
I’ll give you a small thank you gift if you figure it out!
To keep up with the latest recordings from Numbers Stations, check out this database!
http://www.numbers-stations.com/database/
Sources:
https://archive.org/details/ird059
http://users.telenet.be/d.rijmenants/pics/otp-stasi.jpg
http://users.telenet.be/d.rijmenants/papers/one_time_pad.pdf
http://imtranslator.net/translate-and-speak/speak/french/