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08-SSL-and-TLS.md

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SSL and TLS

Secure Socket Layer (SSL) and Transport Layer Security (TLS) are two cryptographic protocols used to provide secure communication over the internet.

SSL was developed by Netscape in the mid-1990s and TLS is its successor. These protocols are used to secure web traffic, email, instant messaging, and other types of internet traffic.

SSL and TLS use a combination of symmetric and asymmetric encryption to encrypt data, ensuring that information transmitted over the internet is secure and cannot be intercepted by unauthorized parties. In this lesson, we will explore the key features of SSL and TLS

SSL & TLS provide functions:

  • Privacy and Data Integrity between Client and Server sides.
  • Privacy (TLS ensures it) – communications are encrypted, so only the Client and the Server have access to that encrypted information. When using TLS, the process starts with an asymmetric encryption architecture. The Server can make its public key available to any Client so that the Client can encrypt data that only that Server can decrypt.
  • Asymmetric and Summetric encryption:
    • Asymmetric encryption allows for that trustless encryption, where you do not need to arrange for the transfer of keys over a different secure medium.
    • As soon as possible thought, you should aim to move from asymmetric toward symmetric encryption, and use symmetric encryption for any ongoing encryption requirements, because computationally, it's far easier to perform symmetric encryption.
    • SO, part of the negotiation process which TLS perform is moving from asymmetric to symmetric encryption.
  • Identity (server or client/server) verified. Even if it's two-way verification, usually it is a Client which verifies the Server, and this is done using public key cryptography.
  • Reliable connection – protect against alteration of data in transit

Three main Phases to initiate secure communication

  1. First, cipher suites are agreed:
  • the first stage focuses on cipher suites.

The cipher suite is a set of protocols used by TLS (different algorithms and their versions for each of these bellows, and specific versions of types grouped together):

  • key exchange algorithm
  • a bulk encryption algorithm
  • and a message authentication code algorithm or MAC
  1. Authentication happens,
  2. Keys are exchanged.

These three point are started when the TCP connection is active between the Client and the Server (L4). And at the end of three phases, there's an encryption communication channel between the Client and the Server.
So, to communicate, the Client and the Server have to agree a cipher suite to use. In other words, it may be called as a Contract.

Please follow the diagram of steps, which explain the establishment of secure connection.

Types of Encryption

Encrypt KEY

The type of encryption used to encrypt the key in TLS is asymmetric encryption. In the TLS protocol, a Client will obtain a website’s public key from that website’s TLS certificate and use that to initiate secure communication.

This process is part of the TLS handshake, where authentication takes place and the keys are established. However, it’s worth noting that TLS also uses symmetric-key encryption to provide confidentiality to the data that it transmits.

Once the secure communication has been established with the asymmetric encryption, the actual data is encrypted and decrypted using a symmetric key. This is because symmetric encryption is generally faster and more efficient than asymmetric encryption.

So, the key in TLS is encrypted using asymmetric encryption.

Encrypt DATA

The type of encryption used to encrypt data in TLS is symmetric encryption.

Once the secure communication has been established with the asymmetric encryption during the TLS handshake, the actual data is encrypted and decrypted using a symmetric key.

This is because symmetric encryption is generally faster and more efficient than asymmetric encryption.

However, it’s worth noting that TLS also uses _asymmetric encryption_ to provide authentication and to establish the symmetric key.

So, the data in TLS is encrypted using symmetric encryption.