🟦 What is TLS? (very important for HTTPS)

TLS = Transport Layer Security

It makes your connection private and secure.

HTTPS = HTTP + TLS

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🔐 What TLS does:

1️⃣ Encryption

Your data becomes unreadable to anyone in between.

Before TLS:

username=rahul
password=1234

After TLS:

8f12a9f9ba98dff91b…

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2️⃣ Authentication

TLS verifies the identity of the server using certificates.

Like checking:

• Are you really talking to “google.com”?
• Not a fake attacker?

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3️⃣ Integrity

Ensures nobody modified the data in transit.

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🔄 How TLS works (very simplified)

Step 1: Client → Server

“Hello, I want to talk securely.”

Step 2: Server → Client

“Here is my certificate signed by a trusted CA.”

Step 3: Client

• Verifies certificate
• Generates a secret key
• Encrypts it with server’s public key
• Sends it to server

Step 4: Server

• Decrypts it
• Now both share the same secret key

Step 5: Encrypted communication begins

This happens in milliseconds.

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🧠 TLS Versions

• TLS 1.0 / 1.1 → old
• TLS 1.2 → widely used

• TLS 1.3 → fastest & most secure

  • 1 RTT or 0 RTT handshake
  • Used by HTTP/3

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📝 Simple summary

Head-of-Line Blocking

• One slow/lost packet blocks all others behind it
• Happens in TCP
• Makes HTTP/2 slower
• Fixed by HTTP/3 (QUIC)

TLS

• Makes HTTPS secure
• Provides encryption, authentication, integrity
• Uses certificates and keys

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