# Lecture: RSA public Key Encryption

### Background Material

### Reading

- Chapter 6 of the text.
- Rivest, R. L., Shamir, A., and Adleman, L., A Method for Obtaining
Digital Signatures and Public Key Cryptosystems, JACM, Vol. 21, No.
2, 1978, pp. 120-126.
(available electronically through the Drexel library - ACM digital library)

### Topics

- RSA Public Key Cryptosystem
- Overview of Public Key Cryptosystems.
- Overview of the RSA algorithm.
- Review Necessary Number Theory and Number Theoretic Algorithms
- Modular Arithmetic
- Greatest Common Divisors and the Euclidean Algorithm
- Fermat's theorem and the Euler phi function
- Modular Inverses
- Modular powers and fast exponentiation
- Extended Euclidean algorithm
- Chinese Remainder theorem

- Proof of correctness

### Slides and Worksheets

- (rsa.ppt,rsa.pdf) -
power point slides containing proofs and background on the
necessary number theory.
- rsa.mw - Maple implementation of the RSA
algorithm and practice questions.

### Practice Assignment

Do the exercises in rsa.mw.
Created: April 21, 2008 (modified Jan 25, 2016) by
jjohnson AT cs DOT drexel DOT edu