RSA

This is a simple RSA library I wrote while working on an small terminal chat application. I know there are probably a million of these things, but this was a learning experience for me. It is fast (thanks to the GNU MP bigint library), easy to use, and can handle practically any key length. I originally tried to write my own bigint library for this, but it was simply too slow when dealing with huge numbers, so I swallowed my pride and used GNU's library instead.

The documentation for this library can be found in include/rsa.h.

Demo

// gcc demo.c -lrsa -lgmp#include<stdio.h>#include<string.h>#include<rsa.h>intmain()
{
rsa_key_tprivkey, pubkey;
rsa_init(privkey, pubkey, 1024, 62);
charmsg[32];
charenc[1025];
chardec[1025];
scanf("%31s", msg);
rsa_encrypt(enc, strlen(msg), msg, pubkey);
printf("Encrypt(%s) = %s\n", msg, enc);
rsa_decrypt(dec, strlen(enc), enc, privkey);
printf("Decrypt(%s) = %s\n", enc, dec);
rsa_clear_key(pubkey);
rsa_clear_key(privkey);
}

Build and Install

/home/user> git clone https://github.com/krglaws/RSA
/home/user>cd RSA
/home/user/RSA> make
/home/user/RSA> sudo make install

Dependencies

The GNU Multiple Precision Arithmetic Library