A s s e s s m e n t

1. Assessment • Class participation—15% • Project on classical ciphers—20% • Group work on cryptanalysis—10% • Written test—25% • RSA—10% • Quantum crypto & Coding Theory—20%

2. Introduction to Cryptography • Cryptography is the study of message secrecy. • Effective cryptography is an essential tool for the protection of privacy & confidential information. • In this course, we will study the development of this secret art from the ancient times to the modern era, learn some classical ciphers, a modern cryptosystem, and certain aspects of Coding Theory.

3. Basic Definitions • Cryptography—the art of creating & writing secret codes. • Cryptanalysis—the art of codebreaking. • Cryptology—cryptography + cryptanalysis • Encryption—process of converting readable information (plaintext) into unreadable gibberish (ciphertext) • Decryption—reverse of encryption • Cipher—the method used in encryption & decryption.

4. Typing in Secret Message Plaintext Encryption Hacker (Doing Cryptoanalysis) Stealing Secret Message Ciphertext Transmitting Secret Message Ciphertext Decryption Figure 1: Illustration of processes in Cryptography Receiving Secret Message Plaintext

5. Development of Cryptography(Group Work) • Research on the development of cryptography from 1900 BC to the 21st century and fill up the timeline of cryptography with the major events that took place or ciphers that were invented. • Read up on the ciphers you come across in your research and other classical ciphers.

6. Quiz Your group score will determine the order in which you get to choose the topic for your project, i.e. the group with the highest score gets to choose first.

7. Qn 1 (2 points) How does the Atbash cipher work? Ans: The first letter of the alphabet is replaced with the last, the second with the second last, and so on.

8. Qn 2 (3 points) Explain how the Scytale cipher works. Ans: The sender and receiver make two round pieces of wood exactly alike in length and thickness. These pieces of wood are called scytales. When a message needs to be sent, the sender winds a scroll of long and narrow parchment around his scytale, leaving no vacant space thereon. The message is then written, the parchment taken off and sent. To read the message, the receiver needs to rewind the parchment around his own scytale.

9. Qn 3 (2 points) In which country was the first Black Chamber formed? Ans: France!

10. Qn 4 (2 points) Who is the author of the world’s first printed book on cryptography? Ans: Johannes Trimethius, a German-born abbott

11. Qn 5 (2 points) The first telegraph line was built in 1844, and stretched a distance of nearly 40 miles between Baltimore, Maryland and Washington, D.C. Messages sent using the telegraph were encrypted using the _________________ (name the cipher)? Ans: Morse code

12. Qn 6 (2 points) Name the person who invented the first Enigma machine. Ans: Dr Arthur Scherbius

13. Qn 7 (2 points) The ADFGX cipher was used by Germany in World War I. What is the name of the French cryptographer who managed to crack the cipher? Ans: Georges-Jean Painvin

14. Qn 8 (2 points) During the Second World War, Japan started to encode high-level diplomatic messages using a machine known as the 97-shiki oobun Inji-ki, which was also called the ___________. Ans: Purple machine

15. Project • Do research on one of the following classical ciphers and prepare a 10-15 min presentation on - the history and development of the cipher - how to use the cipher - pros and cons of the cipher

16. Project Classical ciphers are classified into transposition and substitution ciphers. Choose one of the following ciphers to work on. • Rail Fence Cipher (Group 2) • Caeser Cipher (Group 3) • Playfair Cipher (Group 4) • Pigpen Cipher (Group 1)