Notes on Encryption

Overview of Encryption

• Definition: Encryption is the process of scrambling a message's contents so only certain people can access it.
• Types of Encryption:
  • Symmetric Encryption
  • Asymmetric Encryption

Symmetric Encryption

• Example: Alice sends a sensitive document to Bob.
• Process:
  • Alice encrypts the document with a passphrase.
  • Bob cannot open the document without knowing the passphrase.
• Issue: How to securely share the passphrase?
  • Sending via email is risky due to potential interception.

Asymmetric Encryption

• Purpose: Solves the problem of securely sharing a key for decryption.
• Mailbox Analogy:
  • Publicly accessible mailbox (public key).
  • Only mailbox owner has the key (private key).

Key Generation

• Keypair Generation: Alice and Bob both generate a keypair.
• RSA Algorithm: A popular method for generating keypairs.
  • Generates a public key and a private key.
  • Keys are mathematically linked but cannot be derived from one another.

Communication Process

• Key Exchange: Alice and Bob exchange public keys.
• Message Sending:
  • Alice encrypts her document using Bob's public key.
  • Bob decrypts the document using his private key.
• Security: Only Bob can decrypt the message; Alice cannot decrypt it because she lacks Bob's private key.

Security Considerations

• Private Key Protection: Both Alice and Bob must protect their private keys.
  • If an attacker steals Alice's private key, they can decrypt messages meant for her.
  • They cannot decrypt messages sent by Alice because that requires Bob's private key.

Real-World Applications of Asymmetric Encryption

• Secure Websites: Asymmetric encryption is used in HTTPS.
• Email Security: Used with PGP protocol for secure email communication.
• Cryptocurrency: Bitcoin uses asymmetric encryption to secure wallet transactions.

Conclusion

• Understanding the differences between symmetric and asymmetric encryption is crucial for secure communication.
• Encourage sharing and subscribing for further information.