Communications Fundamentals FAQ

Chapter 5 FAQ

1. 5.11.1 What Is Cryptography and Why Is It Important
   1. What Is Cryptography?
   2. Why Is Cryptography Necessary?
   3. What Security Services Does Cryptography Provide?
   4. Is Cryptography the Same as Encryption?
   5. What Is Encryption?
   6. What Is a Cipher?
   7. How Has Cryptography Changed Over Time?
   8. What Is the Difference Between Symmetric and Asymmetric Cryptography?
   9. Why Doesn't Everyone Use Public-Key Encryption?
   10. Where Is Cryptography Used?
   11. Can Cryptography Be Broken?
   12. Why Is Quantum Computing a Concern?
2. 5.11.2 What Is the Difference Between Encryption and Cryptography
   1. What Is Cryptography?
   2. What Is Encryption?
   3. Why Isn't Encryption Enough?
   4. What Security Services Does Cryptography Provide?
   5. What Is a Cryptographic Hash Function?
   6. What Is a Message Authentication Code?
   7. What Is a Digital Signature?
   8. What Is Key Management?
   9. What Is Public-Key Infrastructure?
   10. How Do Modern Secure Communication Systems Work?
   11. Why Is Encryption Still So Important?
   12. Where Is Cryptography Used?
   13. Why Do People Confuse Cryptography and Encryption?
   14. Why Is the Difference Important?
3. 5.11.3 What Is the Difference Between Symmetric and Asymmetric Encryption
   1. What Is Symmetric Encryption?
   2. Why Is It Called Symmetric?
   3. What Are the Advantages of Symmetric Encryption?
   4. What Are the Disadvantages of Symmetric Encryption?
   5. What Is Asymmetric Encryption?
   6. Why Is It Called Public-Key Cryptography?
   7. How Does Public-Key Encryption Work?
   8. Can Public-Key Encryption Be Used for Authentication?
   9. What Are the Advantages of Asymmetric Encryption?
   10. What Are the Disadvantages of Asymmetric Encryption?
   11. Why Are Both Systems Used Together?
   12. What Are Examples of Symmetric Algorithms?
   13. What Are Examples of Asymmetric Algorithms?
   14. Which Type Is More Secure?
   15. Where Are These Techniques Used?
   16. Will Quantum Computing Affect Both Equally?
   17. Why Is Understanding the Difference Important?
4. 5.11.4 How Does Public-Key Cryptography Work
   1. What Is Public-Key Cryptography?
   2. Why Was Public-Key Cryptography Revolutionary?
   3. How Does Public-Key Encryption Work?
   4. Why Can't Someone Derive the Private Key?
   5. Does Public-Key Cryptography Encrypt Large Files?
   6. What Is a Session Key?
   7. What Is Key Exchange?
   8. How Does Diffie–Hellman Work?
   9. What Is RSA?
   10. What Is Elliptic Curve Cryptography?
   11. What Is a Digital Certificate?
   12. What Is a Certificate Authority?
   13. Where Is Public-Key Cryptography Used?
   14. What Are the Limitations of Public-Key Cryptography?
   15. Why Is Quantum Computing a Challenge?
   16. Why Is Public-Key Cryptography Important?
5. 5.11.5 Why Are AES and RSA So Widely Used
   1. What Is AES?
   2. Why Was AES Developed?
   3. How Does AES Work?
   4. What Key Lengths Does AES Use?
   5. Why Is AES So Popular?
   6. What Is RSA?
   7. How Does RSA Work?
   8. Why Is RSA Important?
   9. Why Isn't RSA Used to Encrypt Everything?
   10. How Do AES and RSA Work Together?
   11. Are AES and RSA the Only Encryption Algorithms?
   12. How Secure Is AES?
   13. How Secure Is RSA?
   14. What Threat Does Quantum Computing Pose?
   15. Will AES and RSA Eventually Be Replaced?
   16. Why Are AES and RSA So Important?
6. 5.11.6 What Is a Digital Signature and How Does It Work
   1. What Is a Digital Signature?
   2. Why Isn't a Digital Signature Just an Electronic Signature?
   3. Why Are Digital Signatures Needed?
   4. What Security Services Do Digital Signatures Provide?
   5. Do Digital Signatures Provide Confidentiality?
   6. How Does a Digital Signature Work?
   7. Why Is a Hash Function Used?
   8. What Is a Message Digest?
   9. Which Keys Are Used?
   10. How Does the Recipient Verify a Signature?
   11. What Is a Digital Certificate?
   12. What Is a Certificate Authority?
   13. Where Are Digital Signatures Used?
   14. Can Digital Signatures Be Forged?
   15. Will Quantum Computers Affect Digital Signatures?
   16. Why Are Digital Signatures Important?
7. 5.11.7 What Is Public-Key Infrastructure (PKI)
   1. What Is Public-Key Infrastructure?
   2. Why Is PKI Necessary?
   3. What Is a Digital Certificate?
   4. What Is a Certificate Authority?
   5. Why Do We Trust Certificate Authorities?
   6. What Is a Root Certificate?
   7. What Is a Certificate Chain?
   8. What Happens When You Visit a Secure Website?
   9. What Information Does a Certificate Contain?
   10. What Is Certificate Expiration?
   11. What Happens If a Private Key Is Compromised?
   12. What Is Certificate Revocation?
   13. How Are Revoked Certificates Checked?
   14. What Is Mutual Authentication?
   15. What Is an Internal PKI?
   16. Where Is PKI Used?
   17. What Are the Limitations of PKI?
   18. Will PKI Change in the Future?
   19. Why Is Public-Key Infrastructure Important?
8. 5.11.8 Why Is Cryptography Based on Mathematics
   1. Why Doesn't Modern Cryptography Depend on Secret Algorithms?
   2. What Is Kerckhoffs's Principle?
   3. Why Is This Principle So Important?
   4. What Makes an Encryption Algorithm Secure?
   5. What Is Computational Security?
   6. What Is a Brute-Force Attack?
   7. Why Does Key Length Matter?
   8. How Large Is 2¹²⁸?
   9. Why Can't Faster Computers Solve the Problem?
   10. What Mathematical Problems Underpin Modern Cryptography?
   11. Why Is Factoring Difficult?
   12. What Is a One-Way Function?
   13. What Is the Avalanche Effect?
   14. What Is Cryptanalysis?
   15. Can Mathematics Guarantee Perfect Security?
   16. Why Are Open Standards Better?
   17. Will Quantum Computers Change This?
   18. Why Is Mathematics the Foundation of Modern Cryptography?
9. 5.11.9 Why Will Quantum Computers Break Today's Encryption
   1. What Is a Quantum Computer?
   2. Why Are Quantum Computers Different?
   3. Why Does Modern Cryptography Depend on Difficult Mathematical Problems?
   4. What Is Shor's Algorithm?
   5. Which Cryptographic Systems Are Affected?
   6. Does Quantum Computing Break AES?
   7. What Is Grover's Algorithm?
   8. Why Is Public-Key Cryptography More Vulnerable?
   9. Should We Be Worried Now?
   10. What Is "Harvest Now, Decrypt Later"?
   11. Which Industries Will Be Affected?
   12. What Is Cryptographic Agility?
   13. What Is Being Done to Prepare?
   14. Does Quantum Computing Mean Cryptography Will Become Obsolete?
   15. Why Is Understanding Quantum Computing Important?
10. 5.11.10 What Is Post-Quantum Cryptography
    1. What Is Post-Quantum Cryptography?
    2. Why Is Post-Quantum Cryptography Needed?
    3. Does Post-Quantum Cryptography Replace Everything?
    4. Why Can't We Wait Until Quantum Computers Exist?
    5. What Makes a Good Post-Quantum Algorithm?
    6. Which Mathematical Problems Are Used?
    7. How Were the New Standards Selected?
    8. Which Algorithms Have Been Standardized?
    9. Why Are There Several Different Algorithms?
    10. Will Existing Systems Need to Change?
    11. What Is Hybrid Cryptography?
    12. What Challenges Remain?
    13. Does Post-Quantum Cryptography Mean Quantum Computers Are Needed?
    14. What Is the Future of Cryptography?
    15. Why Is Post-Quantum Cryptography Important?