Cryptography: Get Stronger Answer Key

  1. A substitution cipher replaces each letter of the plaintext with a letter found by moving [latex]n[/latex] places down or up the alphabet. Example: Using a shift of 3, “ABC” becomes “DEF.”
  2. A transposition cipher rearranges the letters of the plaintext. Example: “HELLO” can become “HLELO.”
  3. “THISISATEST”
  4. “HELLO WORLD”
  5. Key distribution problems, Susceptibility to brute-force attacks.
  6. Faster encryption/decryption, Simpler algorithms.
  7. Key pairs consist of a public key (for encryption) and a private key (for decryption). The public key is shared openly, while the private key remains secret.
  8. To verify the authenticity of a message or document.
  9. Encrypted: [latex]13[/latex], Decrypted: [latex]3[/latex]
  10. Enhanced security, Simplified key distribution.
  11. Slower than symmetric-key methods, More complex algorithms.
  12. Public key cryptography generally offers higher security but depends on key size and implementation.
  13. Symmetric-key methods are generally faster than public key cryptography.
  14. Secure email communication, where key distribution is a challenge.
  15. High-speed network encryption where both parties already share a secret key.
  16. Keys must be securely shared between parties, often using a secure channel or trusted third party
  17. Public keys can be openly shared, while private keys remain secret. Digital certificates can facilitate secure key distribution.
  18. Digital certificates verify the authenticity of public keys, linking them to the entities that own them.
  19. Answers may vary; students might discuss quantum cryptography, blockchain technology, or other emerging trends.