What makes TLS 1 3 necessary

TLS version 1.3

Transport Layer Security, or TLS for short, is a protocol for the authentication and encryption of Internet connections. For this purpose, TLS is pushed as a separate layer between TCP and the protocols of the application layer. The individual tasks include authentication, certification, key exchange, integrity assurance and encryption. The main tasks are to guarantee the authenticity of the contacted remote sites (e.g. server) by means of a certificate and to encrypt the connection between the remote sites.

Each new SSL or TLS version brought additional functions and options, which made the configuration confusing, implementations error-prone and handling cumbersome. Overall, the use of TLS became less secure.
With TLS 1.3 it should be different. That is why every single function of TLS has been checked for benefits and risks to safety. In the process, some parts were removed that, according to current knowledge, do not offer more security and are now partially considered to be unsafe. At the same time, security has been improved with new procedures. Furthermore, measures to optimize performance and preventive hardening measures for future attacks were taken into account.

TLS 1.3 breaks back compatibility for the first time, which unfortunately causes problems in practice. About 1 to 3 percent of all connections with TLS 1.3 break off, which is why the connection is either not accepted while on the move or by a broken web server.

Improvements from TLS version 1.3

  • Connection establishment: The connection is already largely encrypted and makes it difficult to extract information from data connections.
  • Key exchange: The key exchange must be carried out with Diffie-Hellman. Preferably with elliptical curves (ECDHE).
  • Integrity assurance: Authenticated Encryption forces integrity protection and encryption to be combined with one another (with Galois Counter Mode, GCM).
  • Speed ‚Äč‚Äčoptimization: Saving key material for later connections enables faster connection establishment (zero round trip, 0-RTT).
  • ECC cryptography: DJB curve (Curve-22519) and Goldilocks for cryptography based on elliptic curves.

What was explicitly deleted

  • RSA (key exchange)
  • CBC (Cipher Block Chaining)
  • MAC-then-Encrypt (integrity assurance)
  • Functions only compression
  • Functions for renegotiating an existing connection
  • Export Ciphers, MD5, SHA-1, RC4 (cryptographic hash method)

Connection establishment: TLS 1.2 and TLS 1.3 in comparison

When the connection is established, management information for the encrypted connection is exchanged. For example, with whom the client wants to connect, his preferred encryption method and the corresponding key material.

With TLS version 1.3, the connection is encrypted and contains all information in the first step. This saves a step in negotiating the connection.
A passive eavesdropper can no longer clearly identify which server the browser wants to connect to. Previously, he could see this from the name in the certificate that the server sent to the browser in clear text.

Reconnecting a connection (session resumption) is made easier and thus accelerated. With TLS version 1.2, user data could optionally be transported in the first data packet. The client uses the key negotiated during the last connection (pre-shared key). However, this 0-RTT (Round Trip Time) mode harbors the risk of replay attacks, which is why it is subject to restrictions. It's a compromise between speed and security.

Less positive

Regarding the security of Internet connections, there are unfortunately opposing interests. In this way, more security should benefit everyone involved. Unfortunately, this makes it difficult or even prevents the content control of the data traffic. In order to be able to check the data traffic in a defined environment, procedures are required that break the end-to-end encryption in order to check the data packets with virus scanners, intrusion detection systems or data leakage prevention systems.

For TLS 1.3 there is a procedure called "Data Center use of Static Diffie-Hellman".

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