The Cipher suite of TLS 1.3 mainly regulates data encryption, key agreement and authentication use separate trading methods. So there are four different parameters that define exactly how to encrypt a communication with TLS: the TLS protocol version, the key tuning algorithm, the Cipher suite, and the data integrity algorithm. Before the client and server can begin exchanging TLS-protected information, they must securely exchange or agree on an encryption key and code to be used in data encryption (see § Code). the methods used for the key exchange/agreement belong to: public and private keys generated with RSA (in the TLS handshake Protocol TLS_RSA called), Diffie-Hellman (TLS_DH), ephemeral Diffie-Hellman (TLS_DHE), Diffie-Hellman elliptic curve (TLS_ECDH), elliptical ephemere Diffie-Hellman curve (TLS_ECDHE), Diffie-Hellman anonymous (TLS_DH_anon),  pre-shared key (TLS_PSK) and Secure Password Remote (TLS_SRP).  5.1. The applicant`s personal data is processed to enable TLScontact to provide the services, i.e. the acceptance and processing of the visa application on the basis of the agreement concluded with the applicant under these conditions. The TLS_DH_anon and TLS_ECDH_anon Key Agreement methods do not authenticate the server or user and are therefore rarely used because they are vulnerable to man-in-the-middle attacks. Only the TLS_DHE and TLS_ECDHE offer secrecy at the front.
In addition, key convention algorithms should offer the secret of the front, which means that if an attacker ever receives a private encryption key that inevitably allows the attacker to decrypt any future communication based on that key, the attacker should not be able to decrypt past conversations. The only important chord algorithms currently available are Ephemeral Diffie-Hellman (DHE) and Elliptic Curve Ephemeral Diffie-Hellman (ECDHE). The other form of key exchange, available in TLS, is based on another form of public key cryptography invented in 1976 by Diffie and Hellman, the key Diffie Hellman agreement. In Diffie-Hellman, the client and server start creating a public-private key pair. They then send the public part of their key share to the other party. If each party receives the public key share of the others, it combines it with its own private key and ends up getting the same value: the main secret. The server then uses a digital signature to ensure that the exchanges have not been manipulated. This key exchange is called « ephemeral » when the client and server select a new key pair for each exchange. TLS 1.3 now has a radically simpler encryption negotiation model and a reduced set of important options (no RSA, no custom DH settings). This means that each connection uses a key agreement based on DH and the parameters supported by the server are probably easy to guess (ECDHE with X25519 or P-256). Because of these limited choices, the client can easily send DH key shares in the first message instead of waiting for the server to confirm the key shares it wants to support.
This way, the server can learn the common secret key and send encrypted data a round trip earlier. For example, Chrome`s implementation of TLS 1.3 sends an X25519 key share to the server in the first message. In accordance with clause 2, article 437 of the Civil Code of the Russian Federation, this document is a formal offer; If the conditions set out below are accepted, if the holder is authorized to process personal data and the provisional registration is made on the contractor`s website, the person who accepts this formal offer will be the customer in accordance with clause 3, article 438 of the RF Civil Code (the acceptance of the formal offer is in accordance with the execution of the contract under the conditions set out in the formal offer), which are accepted without reservation by the parties….