Building a Secure Connection: The Role of TLS, Symmetric, and Asymmetric Encryption

4 min readMar 21, 2023

To establish a secure connection with TLS certification, the process involves several steps. First, the browser receives and verifies the TLS certificate by checking its validity, expiration date, and trustworthiness of the issuing CA. Second, the browser generates a session key and encrypts it using the server’s public key to establish secure communication with the server. The server uses its private key to decrypt the session key, and then both parties can exchange data using the session key for symmetric encryption. This ensures the exchanged data is protected from unauthorized interception and tampering. The TLS certificate utilizes both asymmetric and symmetric encryption to secure internet connections and provide a secure browsing experience.

Table of Contents

· Symmetric Encryption
· Asymmetric Encryption
· TLS(Transport Layer Security) Certificate
· Secure Internet Connection with TLS Certificate 
  ∘ Step 1: Verification of TLS Certificate
  ∘ Step 2: Exchange of Cryptographic Keys
  ∘ Step 3: Secure Data Exchange

Symmetric Encryption

A type of encryption where the same key is used for both encrypting and decrypting data. This means that both the sender and the receiver of the encrypted data must have access to the same secret key.

To encrypt a message, the plaintext (unencrypted) data is combined with the secret key using an encryption algorithm to produce ciphertext (encrypted) data. The recipient of the message then uses the same secret key and decryption algorithm to recover the plaintext data from the ciphertext.

Asymmetric Encryption

A type of encryption that uses a pair of keys, a public key and a private key, to encrypt and decrypt data, respectively. The public key can be freely distributed and is used to encrypt data, while the private key is kept secret and is used to decrypt the data.

To encrypt a message, the sender of the message uses the recipient’s public key to encrypt the message, and the recipient uses their own private key to decrypt the message. This means that anyone can encrypt data using the public key, but only the recipient can decrypt the data using the private key.

TLS(Transport Layer Security) Certificate

A TLS (Transport Layer Security) certificate is a digital certificate that is used to establish a secure connection between two parties over the internet. When a user visits a website, the website’s server sends its TLS certificate to the user’s browser to verify the website’s identity and to establish an encrypted connection.

The TLS certificate is issued by a trusted third-party organization called a Certificate Authority (CA). The CA verifies the identity of the website owner before issuing the TLS certificate. This verification process involves confirming the domain ownership and the identity of the organization or individual behind the website.

The TLS certificate contains the website’s public key, which is used to encrypt data sent from the user’s browser to the website’s server. It also includes information about the website, such as the domain name, the name of the CA that issued the certificate, and the expiration date of the certificate.

Secure Internet Connection with TLS Certificate

Establishing a secure connection with a TLS certificate involves verifying the validity of the certificate, exchanging cryptographic keys using asymmetric encryption, and encrypting data using symmetric encryption.

Step 1: Verification of TLS Certificate

When a user’s browser receives a TLS certificate, it checks the certificate’s validity by confirming that it hasn’t expired and that it has been issued by a trusted Certificate Authority (CA). Additionally, the browser may check the certificate’s revocation status by contacting the issuing CA’s revocation server. This step is crucial to prevent man-in-the-middle attacks, where an attacker could attempt to impersonate the server and intercept sensitive data.

Step 2: Exchange Cryptographic keys

After the certificate is verified, the browser and the server exchange cryptographic keys using asymmetric encryption. The browser generates a random session key, and then uses the server’s public key to encrypt the session key and send it securely to the server. The server uses its private key to decrypt the session key.

Step 3: Secure Data Exchange

The browser and the server can now exchange data securely over the encrypted connection. Any data sent by the browser is encrypted using the session key and decrypted by the server using the same key, and vice versa. This ensures that the data is protected from interception and tampering by unauthorized parties.