HTTPS: A Conversation between the Client and Server
Tags: https, webdev, security, computerscience
Published: 2023-03-28 21:20:38

## Act I Scene I

Client:

> Hi, good morning.

Server: 

> Good morning, how can I help you today?

Client: 

> I have a question about website security. Why is it that some websites start with "https://" while others start with just "http://"?

Server: 

> That's a great question! Website security is incredibly important in today's digital age, and understanding the difference between "http://" and "https://" is a crucial step in protecting your personal information online. Allow me to explain.

Client: 

> Please do.

Server: 

> When you connect to a website using the "http://" protocol, all data that is transmitted between your browser and the server is sent in plain text. This means that anyone who is able to intercept the data, such as a hacker or someone on the same network as you, can read it. This can include sensitive information like passwords, credit card numbers, and other personal details.

Client: 

> That's worrying.

Server: 

> It is! That's why websites that handle sensitive information, such as banks or e-commerce sites, use the "https://" protocol instead. This protocol uses a secure connection called SSL/TLS to encrypt all data transmitted between your browser and the server, making it much more difficult for anyone to intercept and read your data.

Client: 

> I see. How does SSL/TLS work?

Server: 

> Well, SSL/TLS works by establishing a secure connection between your browser and the server. When you connect to a website using SSL/TLS, your browser and the server engage in a process called a handshake, which allows them to exchange information and establish a secure connection.

Client: 

> Okay, how does that work?

Server: 

> During the handshake, we first agree on a protocol version to use for the connection. Then, I send you my public key, which is included in the digital certificate.

Client: 

> What's a digital certificate?

Server: 

> A digital certificate is an electronic document that contains information about the website's identity and public key. It is issued by a trusted third-party organization called a Certificate Authority (CA).

Client: 

> And how does my browser know which CA to trust?

Server: 

> Your browser has a list of trusted CAs built in. When it receives the certificate from our server, it checks to make sure that it was issued by a trusted CA and that it has not expired or been revoked.

Client: 

> I see. And then what happens?

Server: 

> Once your browser has verified the certificate, you use my public key to encrypt a small piece of data that I can decrypt with my private key. This is called the client key exchange, and it allows us to securely exchange a session key that we will use for the rest of the connection. The session key is generated using a process called key exchange, which uses some randomness from both of us to derive a shared secret. From that point on, all data sent between your browser and our server is encrypted using the session key.

Client: 

> That's fascinating. So using SSL/TLS is really important for protecting sensitive information online?

Server: 

> Absolutely!