#include #include #include #include #include #include void keygen(void); void ran(void); void man(void); void encrypt(void); void decrypt(void); int sqrmul(int,int,int); int invr1(int,int); int invr(int,int); int prime(int); int gcd(int,int); void main() { int chk; do { printf("\n--------------------------------------------------------------------------------\n"); printf("\n *MAIN MENU*"); printf("\n"); printf("\t \t \t \n *PROGRAM TO DEMONSTRATE RSA CIPHER SYSTEM*"); printf("\n--------------------------------------------------------------------------------\n"); printf("\n Press 1 to ENCRYPT:"); printf("\n Press 2 to DECRYPT:"); printf("\n Press 3 to GENERATE KEY:"); printf("\n Press 4 to EXIT:"); printf("\n Please enter your choice......"); scanf("%d",&chk); printf("\n"); switch(chk) { case 1: encrypt(); break; case 2: decrypt(); break; case 3: keygen(); break; case 4: break; default: printf("\n You have enter a wrong choice!!!!!!!!\n"); break; } } while(chk!=4); } void encrypt() { char pln[100]; int len,e,n,tm; printf("\n Enter the plain text:"); cin.getline(pln,'\100'); printf("\n Enter the public key (e,n):"); scanf("%d %d",&e,&n); len=strlen(pln); printf("\n The cipher text is:"); for(int i=0;i0) return 0; else return 1; } int gcd(int a,int b) { int x,y,rem; x=abs(a); y=abs(b); if(x