CS 5173/4173: Computer Security

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Programming Assignment 2: Modular Exponentiation Implementation

Demo is not required for this time. Please submit your codes as instructed. Due on 3:00 pm, 11/01/2018

Write a program (e.g., C, C++) to implement modular exponentiation using the algorithm described on page 23 of lecture 9 notes for public key cryptography. The requirements concerning your codes are

it be written on your own with no assistance from persons other than the professor or the TA, and
it be clear how the code works when read, which can be accomplished through any combination of variable and function names, comments, and code structure that you wish.

Your codes must pass the following test cases (a^b mod n = result):

a	b	n	result
00000001	12345678	12345678	1
00000000	76543210	12345678	0
00000003	000fefef	00000008	3
00000005	32348232	00000011	8
34433445	6cff454f	00000011	9
7fffffff	7eeeeeee	7ddddddd	74e6476c
77777777	34839432	23498834	1d61f4c9
0facade0	0decade0	0abbabad	3e29b63

Turn in:

Your source code files, readme.txt describing how to run your code, and a report including screenshots of the results.
Programs will be graded primarily on correctness of output, but no credit will be given for programs which do not use the basic algorithm covered in the lecture notes.
Also, your codes must TAKE PARAMETERS (i.e., a, b, n), otherwise 25% credit will be deducted for this.

Hint: the product of two ints will often be too large to fit in an int and will overflow, but the product of two ints will always fit in a long.