[Day 2] 3. HTTPS and SSH Encryption

Asymmetric Encryption (Handshake):
- When you visit a website (e.g., https://example.com), your browser requests a secure connection.
- The server sends its public key as part of an SSL/TLS certificate.
- Your browser uses this public key to encrypt a random session key (a symmetric key) and sends it to the server.
- The server uses its private key to decrypt the session key.
Example:
- Public Key (Server):
```
e3f1a...
```
- Random Session Key (Browser):
```
a1b2c3
```
- Browser encrypts
```
a1b2c3
```
  using
```
e3f1a...
```
  and sends
```
Encrypted(a1b2c3)
```
  to the server.
- Server decrypts
```
Encrypted(a1b2c3)
```
  using its private key to retrieve
```
a1b2c3
```
  .
Symmetric Encryption (Data Transfer):
- Both the server and browser now use the session key
```
a1b2c3
```
  for encrypting and decrypting the actual data (e.g., login credentials, form inputs).
Example:
- Browser sends:
```
Encrypted(data)
```
  using
```
a1b2c3
```
  .
- Server decrypts:
```
Decrypted(data)
```
  using
```
a1b2c3
```
  .

Asymmetric Encryption (Handshake):
- When an SSH connection is initiated, the client (e.g., your computer) and server exchange public keys.
- The client generates a session key, encrypts it using the server's public key, and sends it to the server.
- The server decrypts the session key using its private key.
Example:
- Public Key (Server):
```
d4c5e...
```
- Session Key (Client):
```
x9y8z7
```
- Client encrypts
```
x9y8z7
```
  using
```
d4c5e...
```
  and sends
```
Encrypted(x9y8z7)
```
  to the server.
- Server decrypts
```
Encrypted(x9y8z7)
```
  using its private key to retrieve
```
x9y8z7
```
  .
Symmetric Encryption (Data Transfer):
- Both parties use the session key
```
x9y8z7
```
  to encrypt all further communication, including the username and password.
- This ensures that even if someone intercepts the data, they cannot decipher it without the session key.
Example:
- Client sends:
```
Encrypted(username: admin, password: pass123)
```
  using
```
x9y8z7
```
  .
- Server decrypts:
```
Decrypted(username: admin, password: pass123)
```
  using
```
x9y8z7
```
  .

SSH Traffic:
- Appears on TCP port 22 with encrypted packets. The payload (e.g., username/password) is entirely encrypted.
HTTPS Traffic:
- Shows as TLS or SSL packets, with encrypted application data. You won’t see the raw HTTP content without decryption.