How to run the scripts (keygen.c, encrypt.c, decrypt.c)
The scripts go through the process of public key cryptography. To compile the script, type in the command line “make all”. Afterward, you can run each program individually. To generate a pair of private-public keys, type ./keygen followed by the command line options. To encrypt a message, either type “echo [message] | ./encrypt” or use the command line options. To decrypt a message, either type “echo [encrypted message] | ./decrypt” or use the command line options.
Command Line Options
Keygen program options: -b (min number of bits for the public modulus, default 1024), -i (number of iterations for testing primes, default 50), -n pbfile (public key file, default rsa.pub), -d pvfile (private key file, default rsa.priv), -s (seed, default is seconds since the UNIX epoch), -v (enables verbose output), and -h (displays program synopsis and usage). The number of bits has to be greater than 50, if a smaller number is entered, an error would return. You can mix and match the command options. For example, you are allowed to call -b and -i to both set the number of bits and input file.
Encrypt program options: -i (input file to encrypt, default is stdin), -o (output file to encrypt, default is stdout), -n (public key file, default is rsa.pub), -v (enables verbose output), -h (displays program synopsis and usage). Again, you can enter multiple commands.
Decrypt program options: -i (input file to decrypt, default is stdin), -o (output file to decrypt, default is stdout), -n (public key file, default is rsa.priv), -v (enables verbose output), -h (displays program synopsis and usage). Again, you can enter multiple commands.
For more information, type any program name with -h. For example, “./keygen -h”, “./encrypt -h”, or “./decrypt -h”
Files
DESIGN.pdf - shows my general idea and pseudo-code for my code. It has both my initial design and the final one.
WRITEUP.pdf - contains my reflection on the assignment (what I learned) and citations of websites I used while completing the assignment.
README.md - has descriptions on how to run the script, files in the directory, and citations.
Makefile - a script used to compile my sorting file and clean the files after running. You can use it by writing “make {name of function}”.
decrypt.c - implements a decrypt program that deciphers an encrypted message based on a key
encrypt.c - implements an encrypt program that cipher a message based on a key
keygen.c - implements a keygen program that generates the keys that would be used in the abovementioned programs.
numtheory.c - implements an interface for num theory functions that are used for most calculations in the program.
numtheory.h - a header file that has the declaration of all functions used in numtheory.c and specifies its interface
randstate.c - implements an interface for randstate functions that are used to generate random numbers in the program
randstate.h - a header file that has the declaration of all functions used in randstate.c and specifies its interface
rsa.c - implements rsa functions that are used to write and read files as well as encrypt and decrypt messages.
rsa.h - a header file that has the declaration of all functions used in rsa.c and specifies its interface
Citations
1)) GMP lib manual - https://gmplib.org/manual/Integer-Functions
2)) Tutorial on GMP - https://home.cs.colorado.edu/~srirams/courses/csci2824-spr14/gmpTutorial.html
4)) Fopen - https://www.tutorialspoint.com/c_standard_library/c_function_fopen.htm
6)) RSA algorithm visual representation video - https://www.youtube.com/watch?v=j2NBya6ADSY&ab_channel=Programmingw%2FProfessorSluiter
7)) GMP clears - https://machinecognitis.github.io/Math.Gmp.Native/html/a909faa8-4939-1ba3-5647-af8836c9a291.htm
8)) ASCII Table - https://www.freecodecamp.org/news/ascii-table-hex-to-ascii-value-character-code-chart-2/
9)) Diff command - https://www.geeksforgeeks.org/diff-command-linux-examples/