What is cryptography?

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✔️ Cryptography is the practice of keeping information secret, achieved by encrypting or hiding it in such a way that it cannot be decrypted by anyone without access to the proper key.

✔️ Cryptography has two types of keys: symmetric and asymmetric. Symmetric keys are used for everyday use and asymmetric keys, especially in cryptocurrency, have a public and a private key.

✔️ Cryptography has been used throughout history, such as in ancient Egypt and at the time of Caesar.

✔️ Cryptography has been used by governments and organizations to encrypt and decrypt messages, and it has traditionally been an important part of warfare.

Cryptography

Cryptography is a way of keeping information secret.

It is a compound of two Greek words, kryptos and graphein. Kryptos means hidden and graphein means writing or drawing. So you draw or write hidden messages.

The art of cryptography involves encrypting or concealing information in such a way that an overhearing cryptoanalyst cannot, against acceptable effort, infer from the data who is involved and what information is being sent.

Acceptable effort may mean, for example, being able to decipher it in days to decades. Unacceptable effort should involve numbers of years that people do not live, say a hundred years or more.

For example, if you create a complicated password with several different letters, numbers, capital letters and punctuation and make it a certain number of characters long it has been known that in a brute force attack (simply trying all possible combinations) it will take a powerful computer hundreds to thousands of years to guess the password. Or in other words this is an unacceptable effort!

Cryptography is used to give only the sender and receiver the necessary keys and encryption so that no one can listen in.

Cryptography uses two types: the symmetric variant and the asymmetric variant. In the symmetric variant, both sender and receiver have the same set of keys and the decryption key is known before the message is sent.

The asymmetric variant is most common in cryptocurrency. This involves a public and private key. The public key can be known to everyone, the private key is only in the possession of one person because it gives access to the coins themselves. Whoever has the private key can spend these coins.

This variant was first used by Diffie and Hellman. Before these two came up with this solution, couriers had to be used to deliver the decryption key, which of course was rather inconvenient and expensive.

Today, the hybrid variant is most commonly used in companies and governments. The symmetric form for everyday use and the asymmetric variant for passing the private key. This, because the asymmetric variant has more processing power and therefore costs more and is slower.

Well-known examples of cryptography

Cryptography was already in use in ancient times, because messages could be so important that only the recipient with the key should be able to read what it says.

In Egypt, some tombs have anomalous hieroglyphs. It is more than likely that it was a kind of secret writing that only people who knew what the key was could read.

The Kama Sutra also contains cryptography.

In his writings, the Greek writer Lysander talked about the scytale, which was used in the time of Alexander the Great.

Caesar could not be left behind then, although his Caesar figure was fairly easy to decipher with frequency analysis. Caesar used a shifting of the letters by, say, 5 characters. A then becomes f, b becomes g, and so on. Because people know which letters are used most often, you could crack this system.

One of the most infamous stories about cryptography comes from the Babington Betrayal. Babington's cryptography was broken by Phelippes. This contained the plot of Queen of Scots, Mary, against Queen Elizabeth 1 to assassinate her. She was therefore convicted of high treason.

The secrecy of Louis 14 was not broken for a long time.

In the 17th century, all great powers had their own "black room." These were engaged in encoding and decoding messages. Napoleon was defeated with this, because Scovell had broken Napoleon's secret code and Wellington knew exactly what Napoleon was up to.

Edgar Allan Poe popularized cryptography by writing about it in a magazine and later in his novella "The Golden Beetle."

Arthur Conan Doyle had Sherlock Holmes use cryptography to solve the riddle in "The Tale of the Dancing Men," where a pose gave a clue of the letter to be used.

Jules Verne and Dan Brown also used cryptography in their stories.

A story that may be familiar to you is that of Enigma, the Germans' cipher machine, best known for the U-boats, which the British and Poles deciphered.

Secret language is also used by parents, when they share messages in a foreign language in the company of their offspring, if it is not intended for children's ears.

How does cryptography work?

Broadly speaking, cryptography works like this:

1. You want to send a message to another person but no one should know what's in it. That is the plain text, or understandable message.

2. You convert it into Ciphertext, which is a cryptographic representation in ciphers of the text. Without the necessary key, no one can read this text except the recipient, who holds the key.

3. The receiver uses his key to convert the Ciphertext into plain text. Now he can read the message.