🔐 Introduction to Cryptography

Cryptography is the art and science of securing communication and information through the use of codes, so that only intended recipients can understand and process the data. It has been used for centuries, from ancient ciphers to modern-day internet security.

Why Cryptography Matters

• Protects sensitive data from unauthorized access
• Ensures the authenticity of communications
• Maintains data integrity
• Provides confidentiality and privacy

Basic Concepts

There are two major types of cryptography:

• Symmetric Cryptography: The same key is used for both encryption and decryption (e.g., AES).
• Asymmetric Cryptography: Uses a pair of keys — one public and one private (e.g., RSA, ECC).

"Without cryptography, the modern internet would simply not exist as we know it."

Real-World Applications

• Secure messaging (Signal, WhatsApp)
• Secure websites (HTTPS/TLS)
• Blockchain and cryptocurrencies (Bitcoin, Ethereum)
• Digital signatures and certificates

What's Next?

With the emergence of quantum computing, traditional cryptographic algorithms are at risk of becoming obsolete. The next frontier is Post-Quantum Cryptography — designing systems that can withstand quantum attacks.