{"id":689,"date":"2023-05-02T06:11:29","date_gmt":"2023-05-02T06:11:29","guid":{"rendered":"https:\/\/certerassl.com\/blog\/?p=689"},"modified":"2025-11-28T06:46:28","modified_gmt":"2025-11-28T06:46:28","slug":"what-is-ssl-cipher-suite-and-how-it-works","status":"publish","type":"post","link":"https:\/\/certera.com\/blog\/what-is-ssl-cipher-suite-and-how-it-works\/","title":{"rendered":"What is SSL Cipher Suite, and How it Works?"},"content":{"rendered":"\n

If you have a website, you must have an SSL certificate. In general, you’re certainly aware of how SSL certificates work<\/a>. It utilizes the Transport Layer Security (TLS) protocol to ensure that the communication between your website and the web browser (used by the user) is protected and secured.<\/p>\n\n\n\n

Furthermore, an unauthorized third party cannot exploit it; this phenomenon is known as encryption. However, many don’t know what happens behind the curtain when an SSL certificate establishes this connection.<\/p>\n\n\n\n

That is why we intend to focus on cipher suites, an essential component of the encryption process. Let’s explore!<\/p>\n\n\n\n

What is a Cipher?<\/h2>\n\n\n\n

Before seeing a cipher suite, let us understand what a cipher is. A cipher is an algorithm or method used in cryptography to encrypt or code communication to prevent unauthorized access or theft. A cipher usually takes plaintext (the original message) as input and converts it into ciphertext (the coded message) using a specified set of rules or methods.<\/p>\n\n\n\n

Ciphers can range from basic substitution methods like the Caesar cipher to even more complicated computational algorithms like RSA.<\/p>\n\n\n\n

Also Read:<\/strong> What is a Cipher? Types of Ciphers in Cryptography<\/a><\/p>\n\n\n\n

What is a Cipher Suite?<\/h2>\n\n\n\n

A cipher suite is an ensemble of cryptographic algorithms that determine the encryption, authentication, and exchange of keys to secure and protect network connections.<\/p>\n\n\n\n

A cipher suite is a collection of several algorithms and protocols that encrypt and decrypt data sent between the two parties communicating while maintaining it secure and protected from intruders.<\/p>\n\n\n\n

It specifies the encryption<\/a>, key exchange, and message authentication algorithms. Each cipher suite has a distinct combination of algorithms that operate together to provide a specified level of security.<\/p>\n\n\n\n

RSA-AES-GCM-SHA384, AES-CBC-SHA256, and ECDHE-RSA-AES128-GCM-SHA256 are some examples of cipher suites.<\/p>\n\n\n\n

Security requirements, compatibility, and performance requirements with existing systems influence the cipher suite selection.<\/p>\n\n\n\n

What is an SSL Cipher Suite?<\/h2>\n\n\n\n

An SSL cipher, also known as an SSL cipher suite, is a collection of algorithms, steps, or instructions designed to help establish a secure connection between two parties. <\/p>\n\n\n\n

In the most basic terms, the browser (client) and website (server) transmit a series of messages that authenticate the server’s public key and SSL certificate, generate a session key, and encrypt the connection between the client and the server.<\/p>\n\n\n\n

\"SSL<\/figure>\n\n\n\n

Cipher Suites<\/strong> govern the entire procedure. The client provides the server with a list of the cipher suites it allows and supports, and the server selects the most secure, mutually supported cipher suite. <\/p>\n\n\n\n

Depending on the version of TLS<\/a> used, this might happen before or during the handshake. SSL cipher suites decide how to establish a secure connection between entities.<\/p>\n\n\n\n

This communication might occur over HTTPS, FTPS, SMTP, or another network protocol. The primary goal is to prevent hackers and man-in-the-middle (MitM) attackers<\/a> from accessing your data by transforming it into unreadable ciphertext.<\/p>\n\n\n\n

How Does SSL Cipher Suite Work?<\/h2>\n\n\n\n

As stated above, the SSL Cipher Suite is a collection of encryption algorithms<\/a> that protects communication between a web browser & a web server. When a browser connects to a server using HTTPS, it initiates a handshake procedure to create a secure connection. Depending on their compatibility, the browser and server negotiate the cipher suite to employ during the handshake procedure.<\/p>\n\n\n\n

When a message is transmitted across a connection, the data in the message is typically encrypted using a secure SSL connection. A TLS Handshake<\/a> is used to establish this connection. During the TLS Handshake, the client and server exchange available cipher suites to verify they use the same ciphers.<\/p>\n\n\n\n

SSL\/TLS cipher suites specify how to protect a TLS\/SSL connection by indicating which ciphers the client or server uses to generate keys, authenticate users, and so on. To confirm that the ciphers used in the TLS Handshake match and that the client and server can communicate, the client and server must transmit cipher suites to each other.<\/p>\n\n\n\n

The following steps may part the TLS handshake procedure:<\/strong><\/p>\n\n\n\n

Client Hello<\/h3>\n\n\n\n

The client hello phase entails the client sending a request to the server to interact. TLS version, cipher suites supported, and a string of random bytes (usually known as client random) comprise the hello message.<\/p>\n\n\n\n

Server Hello<\/h3>\n\n\n\n

In the server hello, the server confirms the client hello and acknowledges using a TLS version<\/a> that supports\u00a0the client TLS type. The server likewise chooses a suitable cipher suite from the client and sends back\u00a0its certificate, the TLS version, a string of random bytes, cipher suites supported, and the public key to the client (usually known as server random)<\/p>\n\n\n\n

Validation of Certificate<\/h3>\n\n\n\n

The client will verify the validity of the server-side certificate through the CA (certificate authority)<\/a>.<\/p>\n\n\n\n

Pre-Master String<\/h3>\n\n\n\n

At this phase, the client encrypts\/encodes a random length of bytes, termed the “Pre-Master String”, using the server’s public key and passing it back to the server; Hence, just the server can decrypt the key using its private key, providing additional security and privacy to the entire procedure.<\/p>\n\n\n\n

Generating a Session Key<\/h3>\n\n\n\n

The server then decrypts the pre-master key, and the client and the server generate session keys using the client and server random and pre-master string.<\/p>\n\n\n\n

Finished Messaging<\/h3>\n\n\n\n

Lastly, the client and server exchange messages stating that they are done generating and\u00a0comparing keys. The TLS Handshake is completed if the session keys match up, and the session keys are utilized for encryption and decoding any data passed\u00a0between the server and client.<\/p>\n\n\n\n

Since we know the functioning of the TLS Handshake, we can concentrate especially on the cipher suites in a TLS Handshake.<\/p>\n\n\n\n

SSL\/TLS Cipher Suite Components:<\/h2>\n\n\n\n