There encryption – from the Greek kryptos (hidden) e grapia (writing) – It is that set of techniques used to ensure that no one, outside the legitimate recipient, can understand the message that has been sent to him, thus guaranteeing the confidentiality and confidentiality of data. When we talk about confidentiality, we refer to the ability of two entities to exchange messages on the Internet so that Nobody that intercepts the data is able to understand its meaning.
Every message traveling on the network is divided into Cyphose packagesor information units composed of a sequence of bit which indicate, among other information, who is the senderwho is the recipient (both in the form of IP addresses) and which is the message. So if the traffic was not cipheran attacker capable of intercepting one or more packages (attack known as “Man in the middle“) It would be able to understand the entities they are communicating and what they are saying. Different types of encryption, such as symmetrical and asymmetrical encryption, are used as a security and protection tool for the privacyencryption is an example end-to-end of WhatsApp messages.
What is meant by encryption
There encryption It is the process that transforms readable information into a illegible format (Cifrato text) to protect them from unauthorized access. In simple words, it alters the messages, it changes its shape in order to make them illegible, without meaning, except for those who have the right key that can decipher the messages and therefore read them in their original form. The meaning of encryption is also explained in its name, which comes from the Greek kryptos (hidden) e grapia (writing).
This process works using a algorithm (the transformation rule) and one key (secret information) to transform readable data (clear text) into an illegible format (encrypted text), and vice versa.
How cryptography works: symmetrical encryption
The need to encrypt the messages sent is a anything but modern necessity, in fact, already Julius Caesar He used to encrypt military correspondence messages with the so -called “Cesare’s figure”an algorithm of monolylylyte -shaped single -alphabetical encryption. Thanks to this method, an enemy who had intercepted a Roman messenger would not have been able to understand the messages he transported.
The algorithm was simple, each letter was associated with that 3 positions later in the alphabet And this constituted the encrypted message (this is the reason why these algorithms are also called “sliding” or “replacement”). The key to the algorithm will therefore be the vector which associates each letter with the correspondent of the encrypted text.The text “Hello” will therefore become the “FDDR” cyphric string and an attacker who intercepts the message without the key carrier will not be able to reconstruct the original message.
This method, albeit very simple, makes us understand what it is for encrypting messages. It is good to point out that Caesar’s figure It is not a safe encryption algorithm In fact, it is not used in computer science as it has large vulnerabilities due to the analysis of the encrypted text (for example, the letters, in any language, are not all effectively within a phrase).
The example we saw is based on one symmetrical keythat is, the sender who must encrypt the message and the recipient who will have to decipher him share the same key (i.e. the association of the letters of the letters). Algorithms of this type are therefore called a symmetrical encryption and they foresee that the parts exchangesomehow, the key Before you can start encrypting and deciphering the data.
How do our smartphones and PCs to agree on a symmetrical key to be used with a server that perhaps is thousands of km away? The difficulty, at this point, lies in understanding how sender and recipient can locally generate the same key (Operation of “Key Agreement“) To be used as a symmetrical without exchanging it in a clear communication. In this case, in this case, an attacker who intercepted the package containing the key could decipher the data we are sending!
To understand how to do it were Disagree And Hellman who founded the homonymous cryptographic protocol based on the use of very large prime numbers. When we talk about “very large top numbers” we refer to numbers that have over 600 decimal figures.
The difference between the types: asymmetrical encryption
When we browse the Internet on websites that implement the data encryption, therefore, before starting to encrypt the data, we agree with a symmetrical key with the server using algorithms a asymmetrical key in which each entity participating in communication has one pair of keysone to encrypt the messages and one to decipher them.
The key to encrypt the messages is called key and can be shared with anyone, vice versa, the private keyit is secret and is used to decipher the messages. The server will therefore send us its key which will be calculated starting from the public and will be the only one able to decipher the message. An example of asymmetrical key encryption protocol is RSA, still used for services such as digital signature.
The encryption of WhatsApp End to end and the other types
Cryptography therefore represents a security and protection tool for the privacy widely used in many fields. For example, we think about sending a WhatsApp message or to one bank transaction Or, again, to the purchase on an e-commerce and the storage of password.
It will have happened to everyone to read in a WhatsApp chat the message that informs us that messages and phone calls of that chat are protected by end-to-end encryption; Messages that, therefore, can only be read by sender and recipient and not by other subjects or by WhatsApp himself.
The messages will then come ciphe before you actually be sent on the network so that anyone intercept the message it is not able to understand its content and will be deciphered only once they have reached the recipient’s phone thanks to a decrypt key.
WhatsAppas well as Telegramproposes to its users the opportunity to verify that the chat is encrypted and safe through the comparison of a sequence of numbersor emoji In the case of Telegram, on the devices of the subjects in communication: equal sequences confirm the security of the chat.
