Cover photo

Picture yourself shaving your head to deliver a message

Exploring the history of steganography & some fun examples

gm creators!

It's finally Friday, I hope everyone has fun plans for the weekend 😎

I have my apartment set up and am ready to start exploring the city tomorrow. If you live in or have been to NYC, I'd love to hear any recs on things to do or places to eat :)

In case you missed it, yesterday I wrote a post on the history of one of the most important breakthroughs for internet security: public key cryptography. Here's the key takeaway:

The internet would have only a fraction of its current functionality if not for the breakthrough of public key cryptography (aka asymmetric encryption).

With symmetric encryption, you have to find a way to securely let the intended receiver know what the key is beforehand. However, asymmetric encryption enables you to send messages with separate private keys.

Quick analogy: Mailbox : Mailbox Key :: Public Key : Private Key

Check out the full post here!

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Today at a Glance 👓

Recently, I've been reading a new book that has really caught my attention: The Code Book by Simon Singh.

In the first few chapters, Singh mentions a vertical of privacy known as steganography. I had never heard of it until reading, but found the examples really fun to go through.

Steganography is the art of hiding messages or information within another seemingly harmless message or digital file.

I'll go through the history of steganography and provide some fun learnings I came across after doing a bit of reading.

Sections Below:

  1. Write the message on his head...duh

  2. Magician or Cryptographer?

  3. The German microdot

Let's dive in 🚀


Write the message on his head...duh

It's worth noting that steganography is the process of hiding a message pretty much in plain sight, while cryptography is focused on transforming a message to obscure it. In fact, the idea of steganography came way before the first uses of cryptography.

The word steganography comes from Greek steganographia, which combines the words steganós, meaning "covered or concealed", and -graphia meaning "writing". (Wikipedia)

Let's flashback to the Persian empire in 440 BC. During this time, the historian Herodotus recorded one of the earliest known examples of steganography.

According to his writing, Histiaeus, the ruler of a city in Asia Minor, needed to send a secret message to his son-in-law, Aristagoras, in Greece. To securely transmit his message, Histiaeus shaved the head of his most trusted servant, tattooed the message onto the servant's scalp, and then waited for his hair to regrow to conceal the tattoo. Once the servant’s hair had grown back, he made his way to Greece. Aristagoras shaved the servant's head again to reveal and read the hidden message.

Source

I have to admit, as funny as the story is, it's really freaking smart. Of course, it did require Histiaeus to wait for the servants hair to grow back so not efficient, but 10/10 idea to conceal the message.

Other early examples of steganography include Demaratus, a Greek native living in Persia, sending a warning about a potential Persian attack to his home state Sparta. He wrote the message on a tablet and then covered it with wax. Wax tablets were common in those days so nothing seemed suspicious - he simply wrote the message before applying the wax.

The Chinese also used to write messages on silk paper and then cover it with wax. They would have the messengers swallow the crumpled up note and then eventually deliver it to the right person 🤮


Magician or Cryptographer?

The more contemporary start to both steganography and cryptography can be traced back to the 1400s. Joahannes Trithemius, also know as the founder of modern cryptography, was the first to execute a clever way of hiding information in plain sight.

Trithemius was a German monk and polymath who was also obsessed with occultism, the belief and practice of mythical/supernatural ceremonies.

One of Trithemius’ most famous works is Steganographia. This book is basically the first how to guide on cryptography and steganography. The cool part was that the entire text is disguised as a "silly" book on magic - it's pages are filled with incantations but in reality are actually coded messages.

Steganographia

What I love about this story is that it's a perfect example of how similar the need for secret content was back then! The church essentially banned any speech on mythical knowledge so Trithemius basically kicked off the field of cryptography by encoding his passion.

Some folks think that he actually stumbled onto the idea by luck and that he gets more credit than deserved. They believe that he was actually trying to demonstrate a magic trick and was less so intending on actually demonstrating ciphers. Imo, these people are just haters. Regardless of his motives, just the skill required to encode a whole book with nothing but a pen and paper is far more difficult than what most are capable of.


The German Microdot

The last example I want to talk about goes back to more recent times.

During WWII, the Germans notoriously used steganography to hide messages on microdots. Essentially, they would shrink the real message down into a single period on a letter that seemed harmless if anyone read it.

Microdot Camera

The US eventually caught on however and were able to start intercepting the hidden messages.

Microdots are still used today - for example, printer companies will add a tracking number/stamp with their information on it.

However, as cryptography started gaining steam in the last 100 years - especially digital cryptography - the need for steganography has relatively gone down. At the end of the day, no matter how securely hidden the message is, it's still risky displaying top secrets as is. The best practice is to combine both steganography and cryptography to ensure true privacy.


That's all for today's post - if you enjoyed, I'd love for you to share with your friends in crypto :)

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