1. HTTP (Hypertext Transfer Protocol)
What it is: HTTP is the foundational protocol used for transferring data on the web.
Purpose: It allows browsers to communicate with web servers to fetch and display web pages.
How it works: When you enter a URL in your browser, an HTTP request is sent to the web server. The server then responds with the requested web page.
2. HTTPS (Hypertext Transfer Protocol Secure)
What it is: HTTPS is the secure version of HTTP.
Purpose: It is used to secure communication over a computer network, such as the internet.
How it works: HTTPS encrypts the data exchanged between the user's browser and the website, making it more secure against eavesdropping and man-in-the-middle attacks. This encryption is done using SSL/TLS.
3. SSL (Secure Sockets Layer)
What it is: SSL is a standard security technology for establishing an encrypted link between a server and a client.
Purpose: It ensures that all data passed between the web server and browsers remain private and integral.
How it works: SSL uses a system of cryptographic keys, including a public key that is shared and a private key that is kept secret. When a browser connects to a secure site, the SSL certificate provides proof that the website is authentic and establishes an encrypted link.
4. TLS (Transport Layer Security)
What it is: TLS is the successor protocol to SSL.
Purpose: It provides privacy and data integrity between two communicating applications.
How it works: TLS is very similar to SSL but offers more robust encryption algorithms and improved security measures. It also operates in the same way, establishing an encrypted connection between a client and a server.
Relationship Between Them
HTTP vs. HTTPS: HTTPS is HTTP with encryption and security added by SSL/TLS.
SSL vs. TLS: TLS is an updated, more secure version of SSL. While many people still refer to these protocols as "SSL," most modern applications use TLS.
When we visit a website using HTTPS, SSL/TLS is used to encrypt the connection. The process begins with a handshake where the server provides a certificate to the client, which then uses it to establish a secure connection. This ensures that any data exchanged is encrypted and secure.
SSL Certificate
What it is: An SSL certificate is a digital certificate that authenticates a website's identity and enables an encrypted connection.
Purpose: It ensures that data transferred between the website and the user is encrypted and secure.
How it works: The SSL certificate contains information about the certificate holder, the certificate's serial number and expiration date, a copy of the certificate holder's public key, and the digital signature of the certificate-issuing authority.
In the context of HTTPS, an SSL certificate is crucial as it authenticates the website and enables encrypted connections. This certificate includes the website's public key, and it's issued by a trusted Certificate Authority (CA).
Encryption, achieved through algorithms, ensures that data is unreadable to anyone except those possessing the corresponding decryption key. Public and private keys are used in this process: the public key is shared and used for encryption, while the private key is kept secret and used for decryption.
The chain of certificates, from the SSL certificate through intermediate certificates to the root certificate, establishes a trust chain. When a browser connects to a secure site, it verifies this chain to ensure the site's SSL certificate is valid and trustworthy, thus securing the connection.
How Clients Encrypt Data Without the Private Key
In SSL/TLS communication, the server sends its public key to the client as part of the SSL certificate.
The client generates a random piece of data called the pre-master secret.
The client encrypts this pre-master secret using the server's public key and sends it to the server.
The server decrypts the pre-master secret using its private key.
Both the client and server use the pre-master secret along with exchanged random values to generate the master secret.
The master secret is used to derive symmetric session keys for encryption and decryption.
Both the client and server use this secret to generate symmetric session keys, which are used to encrypt and decrypt data for the duration of the session.
This ensures that the communication remains secure, even though the private key is never shared with the client.
Summary
HTTP is the basic protocol used for transferring web pages over the internet. However, to ensure the security and privacy of the data exchanged, we use HTTPS, which stands for Hypertext Transfer Protocol Secure.
HTTPS secures data transferred over the web using SSL/TLS protocols. An SSL certificate containing the server's public key is sent to the client. The client encrypts a pre-master secret with the server's public key and sends it back. Both client and server then generate symmetric session keys from this pre-master secret. These session keys are used to encrypt and decrypt data for the duration of the session, ensuring secure and efficient communication.