Cryptography is a method of protecting information so only the right person can read it.
The easiest analogy:
It is like locking your message in a box with a unique key. Only the person who has the exact key can open it. In digital world, the key is math.
How Does Cryptography Work?
It uses mathematical formulas to turn readable information into something that looks like nonsense.
Think of 3 steps:
1. Encryption
Turning your message into secret code.
Example:
“Hello” → 5f9a12c0e2…
2. Transmission
You send the coded message over internet, WiFi, Bluetooth, doesn’t matter. Even if someone steals it, they only see nonsense.
3. Decryption
The receiver uses a key to unlock the code and read the real message. If you don’t have the key, even supercomputers can’t break it.
Why It is Important?
Because the internet is basically an open world. Anyone can intercept a message, but cryptography ensures your data safety.
What Problems Does It Solve?
1. Privacy (Keeping data secret)
Your messages remain private.
2. Integrity (No tampering)
Ensures data hasn’t been changed.
3. Authentication (Who are you?)
Verifies identity.
4. Non-repudiation
Non-repudiation ensures that a signed message or transaction can be verified as coming from the claimed sender.
5. Secure communication in hostile environments
Even during war or government communication.
• Who Invented Cryptography?
It has existed for thousands of years.
Earliest users:
Ancient Egyptians used secret symbols
Greeks used the "Scytale cipher"
Romans used Caesar Cipher (simple shifting letters)
But modern cryptography (strong math-based) was invented by:
Claude Shannon (1940s) — father of modern cryptography
Developed encryption theory during WW2.
Whitfield Diffie & Martin Hellman (1976)
Invented public-key cryptography, which is the foundation of Bitcoin, WhatsApp, HTTPS, everything.
Rivest–Shamir–Adleman (RSA, 1977)
Created the RSA encryption algorithm.
• Who Used Cryptography First in Modern History?
Military (WW1 & WW2)
For hiding battle plans.
Governments & Intelligence Agencies for secure communication.
Banks
Where Is It Used Today?
It is everywhere in modern life.
You use it every single day, even if you don’t notice.
1. BTC & Blockchain
Wallets
Private keys
Signatures
Mining
Hashing
Without cryptography: BTC doesn’t exist.
2. WhatsApp
End-to-end encryption.
3. Internet Browsing (HTTPS)
Every website uses TLS/SSL cryptography.
4. Banking Apps
Login security, Payment authorization, Fraud prevention
5. Mobile Networks
Encrypted signals.
6. Cloud Services
Files are encrypted.
7. Password Managers
8. Digital Signatures
Used in:
Government documents
Corporate agreements
Smart contracts
9. Cybersecurity Tools
Firewalls, VPNs, encrypted disks.
10. AI & Data Security
Encrypting models, datasets, and user information.
Conclusion:
Cryptography is the backbone of trust on the internet.