How Does SSL And TLS Work?


How Does SSL And TLS Work? – This is the first step towards protecting your domain. main.


Secure Sockets Layer (SSL) certificates, also known as Transport Layer Security (TLS) certificates, are required for securing internet browser connections and transactions through data encryption. Here’s how TLS/SSL works behind the scenes to keep your online transactions and logins safe.

Every time you visit a website, a process is known as the “TLS/SSL handshake” creates a secure connection between your web server and web browser almost instantly, invisible to the end-user. HTTPS and the little padlock icon in the browser address bar are displayed on websites secured by a TLS/SSL certificate. TLS/SSL certificates are used to protect end users’ data while it is being transferred, as well as to validate the website’s company identification to ensure users are communicating with real website owners.


  1. Each TLS certificate is made up of a public key and a private key pair.
  2. Because they interact behind the scenes during online transactions, these keys are crucial.
  3. The client-server and web browser communicate every time you visit a website to ensure a secure TLS/SSL encrypted connection.
  4. When a web browser (or client) navigates to a secure website, the website server exchanges its TLS/SSL certificate and public key with the client to create a secure connection and a unique session key.
  5. The browser verifies that it recognizes and trusts the SSL certificate’s issuer, or Certificate Authority—in this example, DigiCert. The browser additionally verifies that the TLS/SSL certificate is valid, has not expired, and has not been revoked.
  6. The server decrypts the symmetric session key with its private key after receiving it from the browser. To begin the encrypted session, the server sends back an acknowledgment encrypted with the session key.
  7. The session key is now used by both the server and the browser to encrypt any sent data. They start a secure session that protects the privacy, integrity, and security of the messages as well as the server.

How Does SSL And TLS Work?

These are the fundamental concepts to master to comprehend how SSL/TLS works:

  1. The TLS handshake is the first step in secure communication, in which the two communicating parties establish a secure connection and exchange the public key.
  2. The two parties produce session keys during the TLS handshake, and the session keys encrypt and decrypt all communications after the TLS handshake.
  3. Each new session uses a different session key to encrypt conversations.
  4. TLS verifies that the party on the server-side, or the website with which the user is engaging, is who they say they are.
  5. TLS further assures that data is not tampered with since it includes a message authentication code (MAC) with transmissions.

TLS encrypts both HTTP data sent by users to websites (by clicking, filling out forms, etc.) and HTTP data sent by websites to users. The recipient must use a key to unlock encrypted data.

The TLS handshake

The TLS handshake is the first step in any TLS communication session. Asymmetric encryption is utilized in a TLS handshake, which means that two distinct keys are used on both ends of the conversation. This is made feasible by a technology known as public-key cryptography.

Two keys are used in public-key cryptography: a public key that the server makes public and a private key that is kept secret and only utilized on the server-side. Only the private key can decrypt data encrypted with the public key and vice versa.

During the TLS handshake, the client and server exchange randomly generated data using their public and private keys, and this random data is used to generate fresh session keys for encryption.

Symmetric encryption with session keys

In contrast to asymmetric encryption, symmetric encryption uses the same key for both parties in a discussion. Following the TLS handshake, both parties encrypt using the same session keys. The public and private keys are no longer used after session keys are utilized. Session keys are one-time use keys that are not reused once the session has ended. For the next session, a new set of session keys will be generated at random.

Authenticating the origin server

The origin server must be authenticated.

A message authentication code, or MAC, is a digital signature that confirms that the transmission originated from the actual website in TLS communications from the server. This protects the server against on-path assaults and domain spoofing by authenticating it. It also assures that data has not been tampered with during transmission.

What is an SSL certificate?

An SSL certificate is a file that is put on the origin server of a website. It’s basically a data file containing the public key and the website owner’s identification, as well as other details. TLS cannot encrypt a web site’s traffic without an SSL certificate.

Any website owner can technically create their own SSL certificate, which is referred to as self-signed certificates. Self-signed certificates, on the other hand, are not as trusted by browsers as SSL certificates issued by a certificate authority.

How does a website get an SSL certificate?

A certificate authority must issue an SSL certificate, which must subsequently be installed on the webserver (often a web host can handle this process). A certificate authority is a third-party organization that verifies that the website owner is who they claim to be. They preserve a copy of each certificate they hand out.

Is it possible to get a free SSL certificate?

SSL certificates are often charged by many certificate authorities. Cloudflare provides free SSL certificates to help make the Internet more secure. Cloudflare was the first firm to do so in terms of Internet security and performance. Cloudflare has also worked to improve SSL/TLS performance so that websites transitioning from HTTP to HTTPS experience no degradation in performance. Learn more about SSL and Cloudflare.

What is the difference between HTTP and HTTPS?

HTTPS stands for “secure,” and it’s simply HTTP with SSL/TLS. A legal SSL certificate issued by a certificate authority is required for a website with an HTTPS address, and traffic to and from that website is authenticated and encrypted using the SSL/TLS protocol.

Many web browsers have begun to flag HTTP websites as “not secure” or “unsafe” to urge the Internet as a whole to transition to the more secure HTTPS. As a result, HTTPS has become vital for not only keeping users safe and user data protected, but also for creating trust with users. Check for SSL/HTTPS flaws on a website.