Cryptography Part 1: the past

The endless story? Violation of data protection by using ip location tracker in major companies dominates newspaper headlines around the world. It has become a recurring topic in reporting, and companies are also becoming increasingly aware of the need to protect sensitive data from third-party access. The Ponemon Institute has observed a steady increase in the implementation of business encryption strategies in the past 14 years.

Legal regulations, especially within Europe, compel companies to use encryption services. An important factor here is the General Data Protection Regulation (GDPR) or GDPR, which has been in force since May 2018. Personal data must be encrypted as soon as it is transmitted over the Internet or stored in the cloud, while the Encrypted communication was hardly considered at all a few years ago, it is currently “in vogue.”

It is important to note that encryption is not a modern invention. From a historical point of view, the beginnings go back centuries, as we know the Roman commander Cayo Julio César already exchanged encrypted messages with his military leaders. In this article, we’ll take a look at the past to better understand today’s crypto.

Before entering our time machine, fasten your belts to hunt for tracks, we want to inform you that side effects such as nausea, headaches, and confusion can occur during this trip. We will try to provide the best possible service during your journey through the history of crypto. Fasten seat belts!

Historical cover-up – also known as lemon juice on parchment

In 480, we are in the middle of Antiquity. Roman commanders compete for the government of the Roman kingdom. Intrigue, murder, and other fraudulent activities must be planned and carried out. But how can such a murder be transmitted undetected? Have you heard of lemon juice on parchment? It represented a classic secret communication channel.

The text was written on parchment using lemon juice. After the lemon juice dried, the parchment gave the impression of a blank sheet. The recipient of the message could still decode the message very easily. For example, in those days he held a candle behind the parchment and thus was able to make the lemon juice visible and read the message.

Furthermore, there were several other methods that were used in Antiquity. Slaves were used to shave the hair off their heads, tattoo the message on the back of their heads, and wait for the hair to grow back to deliver the message to the rightful recipient. This was undoubtedly one of the most radical media outlets, and it was also not suitable for urgent messages.

The procedures just described belonging to steganography, which is clearly distinguishable from cryptography. Steganography is based on the hope that a “foreigner” does not realize that two private parties are communicating with each other.

Beginnings of cryptography: Asterix and Obelix visiting Caesar

Instead of the steganography, cryptographic communication occurs between two or more partners, and language may be visible, but remains confidential. Only the information itself is not visible to foreigners, through the encryption of the message.

Let’s locate ourselves in Rome. We are going to immerse ourselves in the world of the Gauls and Romans.

A popular encryption technique was developed by a well-known historical personality: Gaius Julius Caesar. Known today as the Caesar cipher, the later Roman emperor communicated with his military leaders through encrypted messages. Neither unauthorized persons nor the enemy, in this case, the Gauls, knew the purpose of the coded texts. But as time went on, this encryption method could be discovered in different ways.

The Caesar cipher is a symmetric encryption method is based on simple and substitution. This means that each letter used in the message is replaced by a new letter. The replacement letter results from a letter offset within the alphabet that is determined in advance. For example, a three-digit offset. In this case, “Thank you” becomes “Gdqnh”. The decryption of an encryption disk is often used to avoid having to constantly repeat the alphabet. With this type of encryption, the recipient only had to be informed in advance with a secret key.

An initially unauthorized person couldn’t get anything out of the message without the key, but once some time has passed, it’s easy to decrypt the message after an average of 25 tries. This is because they had to check the alphabet to discover the correct offset of the letter. Today’s computers would take less than a second to do this. Therefore, Caesar’s encryption is no longer considered secure and has been superseded by more recent methods. Are you ready? We are going to France in the 16th century.

Cryptography Part 1 – Discover the origin of encryption

Discover the origin of stenography through history

From Rome to France

One of the methods that replaced Caesar encryption as a more secure alternative was developed by the French diplomat and cryptographer Blaise de Vigenére in the 16th century, also known as Vigen-re encryption. It is comparable to Caesar encryption, and is also based on letter substitution, but uses multiple encrypted text alphabets.

The number of alphabets used is determined by a key. Instead of a number, a keyword is chosen, which is written under the encrypted message. The keyword specifies the letter offset for each of them. The first letter of the keyword defines the alphabet for the first letter of the clear text, the second letter of the keyword determines the alphabet for the second letter of the original text.

Example of a Vigenére figure

Keyword: Present Message: “We give Tom a voucher for his birthday”

“We give Tom a Voucher for his Birthday”

The “P” now gives a letter offset of sixteen letters, since the “P” is in the sixteenth position in the alphabet. The “R” changes eighteen letters and so on. So “WE” becomes an “MW”.

The security of this encryption method is strongly related to the length of the key and whether the key is used multiple times. Therefore, the keyword in our example is not really safe.

However, some years later this encryption method turned out to be easily decoded. Now we will take a look at another encryption method that was considered undecipherable for a long time.

Enigma and the Turing machine

We made a stop in Germany in the 1930s. Like Caesar encryption, encryption methods were mainly used in a military context. Therefore, it is not surprising that Germany also made use of encrypted communication during World War II. The special aspect of this type of encryption was that it was encrypted and decrypted using a machine. The key was changed every day, so it lost its validity after 24 hours. That machine is called Enigma.

Enigma was invented by Arthur Scherbius in 1918 as a special machine for routine encryption and decryption. The basic operating concept dates back to the years of the First World War. World War I is considered the first war in which cryptography was used systematically. Already during the war and in subsequent years, the first machines were developed that offered a significantly higher level of safety than manual methods. Enigma was offered for sale but received with little interest from both the business community and government agencies. It was not until 1933 when Hitler made Enigma become part of the standard team of the National Socialists. But how exactly does this strange machine work?

At first glance, it resembles a classic typewriter, but inside it hides a rather complicated system. The operating principle is based on simple electrical circuits, each connecting a key with a letter on the keyboard to an electric light that illuminates a letter on the screen. However, “A” is not connected to “A” on the display panel: all rollers are interlocked according to a specific system. Therefore, the message can only be decoded if the recipient knows all the settings of the transmitting puzzle.

Sounds like unsurpassed encryption, right? But it was deciphered by a British computer programmer in 1941. Alan Turing declared war on Enigma with a “machine Turing ‘ self-developed and eventually won. Historians claim that this machine prematurely ended World War II and saved millions of lives.

Principle of modern cryptography

Before you return to the office, we want you to come to a conclusion:

As you have learned in our various phases, even systems whose encryption algorithm was known only to the receiver and the sender were able to be decrypted. A principle of modern cryptography, also known as the Kerckhoff principle, states that the reliability of a (symmetric) encryption method relies on key security rather than algorithm secrecy. Therefore, it is advisable to use public algorithms that have already been sufficiently analyzed.