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Lesson Objectives   Lesson Information   Slideshow   References   Questions

Lesson Objectives

1. Introduce the classic cryptographic characters and problem.
2. Describe the differences of information theoretic and computational complexity cryptographic techniques.
3. Describe the two types of cryptography: symmetric and asymmetric.
4. Describe and analyze one time pads.

Lesson Information

This lesson is a basic introduction to cryptography. It looks at the common players in cryptographic schemes. Information Theoretic crypto systems are introduced. These systems provide provably secure communication. Computational Complex crypto systems are the alternative the Information Theoretic crypto systems. These systems are based on the difficulty of solving a problem. A basic introduction to symmetric key and asymmetric key cryptography is given. Finally, one time pads are introduced and analyzed.

Slideshow

Cryptography Slides from the University College, UNSW, Australian Defence Force Academy, School of Computer Science

References

Notes on Cryptography, Charles Blair

Crypto Today, Tom Dunigan

Cryptography and Data Security, Peter Gutmann

Introduction to Cryptography, Lawrie Brown

Questions

Listed below are a number of questions to assess your knowledge of the lesson objectives covered in this lesson. You can check your answers by scrolling down to the bottom of the document and checking the answer key.

1. (T/F) In the classical cryptographic problem, the main characters are Allen (the sender), Bob (the receiver), and Lucifer (the eavesdropper).
2. __________ systems are those systems that have proofs of their security.
3. (T/F) An example of a symmetric key cryptosystem is a one time pad.
4. (T/F) One time pad cryptosystems are practical, secure, and efficient to implement.
5. Another name for asymmetric cryptography is _____________ cryptography.
6. The most popular cryptosystems are vulnerable to brute force attacks and are based on an unproven computational assumption. These cryptosystems are called___________________.
7. (T/F) One time pads are easy to break assuming that an attacker has a mild amount of computational power.
8. (T/F) Symmetric key cryptography has the property that the encode function and the decode function are the same.
9. (T/F) Given two one time pad ciphertexts c1 and c2, it is possible to determine within a reasonable probability if they use the same key.
10. (T/F) RSA and RC5 are two examples of public key cryptosystems.

Answer Key

1. The answer to question 1 is False.
2. The answer to question 2 is Information Theoretic.
3. The answer to question 3 is True.
4. The answer to question 4 is False.
5. The answer to question 5 is Public Key.
6. The answer to question 6 is Computationally Complex.
7. The answer to question 7 is False.
8. The answer to question 8 is True.
9. The answer to question 9 is True.
10. The answer to question 10 is False.

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