Encryption / Cryptography

Encryption is originally a procedure by which we make our messages and documents unreadable by unauthorized persons. Today, it is a little more than that, encryption often means the requirements related to the signature, such as the authenticity and inviolability of a document.

Encryption is a process by which we make our confidential messages unreadable by unauthorized persons. This is an old demand, and there were old solutions for it, except that with the development of computer capacities, essentially all such procedures became easily hackable. 

For centuries, encryption worked by having those who exchanged confidential letters agree on a cipher solution (the key). With this, they transcribed (encoded) their original messages and then sent the coded text to the other party, who produced (decoded) and read the message using the same key. 

So the two parties used the same key (symmetric encryption), which raises many problems. The main problem in this case is that the parties must agree on the key before exchanging messages, which is why, for example, we cannot send encrypted messages to strangers. 

This problem was solved by one of the top intellectual products of the previous century, asymmetric encryption. In this, each actor has a public key and a private key. By using the drawee 's public key, the sending party can apply the drawee 's private encryption key to the message to be sent, but does not recognize the key itself. The drawee can then easily read the message, since he only needs to use his own private key.

It sounds simple, but in reality there are huge computing capacities in the background, because the unbreakability of private keys is ensured precisely by the fact that an essentially infinite amount of computing operations would have to be performed in order to learn them.

Nowadays, the concept of encryption has been supplemented with meanings that can actually be linked to the signature. On the one hand, this is proof of the authenticity of the document, i.e. that it was really sent by the person who is written as the sender. The inviolability of the document must also be proven, i.e. that the text has not changed since it was signed or sent. (This scope also includes the non-repudiation of the document, i.e. the fact that the signatory cannot deny that he knows and has read the document. However, the latter is really much more connected to the signature than to the encryption.) 

These signature-related requirements (inviolability, authenticity, non-repudiation) are not fully satisfied by asymmetric encryption either, so additional procedures are required.