What is encryption and what are the differences between symmetric and asymmetric encryption?

Encryption is the process of converting readable data (plaintext) into an unreadable format (ciphertext) to protect information from unauthorized access.\n\n**Why encryption is essential:**\n• **Data confidentiality** - Protects sensitive information from unauthorized viewing\n• **Compliance** - Required by regulations (GDPR, HIPAA, PCI DSS)\n• **Trust** - Enables secure communication and transactions\n• **Risk mitigation** - Reduces impact of data breaches\n\n**Symmetric encryption:**\n\n**How it works:**\n• **Single key** - Same key used for both encryption and decryption\n• **Speed** - Fast processing, suitable for large amounts of data\n• **Key sharing** - Both parties must securely share the secret key\n\n**Common algorithms:**\n• **AES (Advanced Encryption Standard)** - Current standard, 128/192/256-bit keys\n• **DES (Data Encryption Standard)** - Older, 56-bit key (now considered weak)\n• **3DES (Triple DES)** - Applies DES three times for better security\n\n**Use cases:**\n• File and disk encryption\n• Database encryption\n• VPN tunnels\n• Bulk data encryption\n\n**Asymmetric encryption (Public Key Cryptography):**\n\n**How it works:**\n• **Key pair** - Two mathematically related keys (public and private)\n• **Public key** - Can be shared openly, used for encryption\n• **Private key** - Kept secret, used for decryption\n• **One-way process** - Data encrypted with public key can only be decrypted with private key\n\n**Common algorithms:**\n• **RSA** - Widely used, based on factoring large prime numbers\n• **ECC (Elliptic Curve Cryptography)** - Smaller keys, same security level\n• **Diffie-Hellman** - Key exchange protocol\n\n**Use cases:**\n• Secure key exchange\n• Digital signatures\n• SSL/TLS certificates\n• Email encryption (PGP/GPG)\n\n**Comparison:**\n\n| Aspect | Symmetric | Asymmetric |\n|--------|-----------|------------|\n| **Keys** | One shared key | Key pair (public/private) |\n| **Speed** | Fast | Slower |\n| **Key distribution** | Challenging | Easy (public key) |\n| **Scalability** | Poor (n² keys) | Good (2n keys) |\n| **Use case** | Bulk encryption | Key exchange, signatures |\n\n**Hybrid approach:**\nMost secure systems combine both:\n1. **Asymmetric encryption** - Securely exchange symmetric key\n2. **Symmetric encryption** - Encrypt actual data with shared key\n3. **Example** - HTTPS uses RSA/ECC for key exchange, AES for data encryption\n\n**Best practices:**\n• Use strong, up-to-date algorithms\n• Implement proper key management\n• Regular key rotation\n• Secure key storage (HSMs, key vaults)\n• Never implement custom cryptography