What is Cryptography?

📝Cryptography (from “hidden” + “writing”) is the science of methods that allow you to provide:

1️⃣Confidentiality (inability to read information to outsiders);

2️⃣Data integrity (inability to imperceptibly change information);

3️⃣Authentication (authentication of authorship or other properties of an object);

4️⃣Encryption (data encoding).

📖Texts began to be encrypted already in the third millennium BC. Both in the Roman Empire and in the Middle Ages, important messages and military orders were encrypted.

🤴🏼For example, Julius Caesar used a very simple form of cryptography for his messages, known as a “shift cipher”. Each letter in his text was replaced by the third letter in the alphabet. So instead of A, he wrote D. The recipient had to know the cipher code to read the right words.

⚔️During the Second World War, special devices were already used to encrypt messages — cryptography became more complicated. It took the military several years to unravel the keys and read the messages of other countries.

🔐Today, cryptography is able to guarantee the security of information much more reliably, and the ciphers that Caesar once used can now be solved in a couple of seconds.

In modern cryptography, symmetric and asymmetric encryption are distinguished.

1️⃣Symmetric encryption means that both parties involved in data exchange have exactly the same keys for encrypting and decrypting data.

2️⃣Asymmetric encryption involves using two different keys in a pair — public and secret (private). In this method, the keys work in pairs: if the data is encrypted with a public key, then they can only be decrypted with the corresponding secret key, and vice versa.

🗃️Cryptography knows many different methods of data encryption. Many of them are based on complex mathematical structures such as elliptic curves, rings, and finite bodies.