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#include <iostream>
#include <fstream>
#include <cstdlib>
using namespace std;
typedef unsigned int s64;
typedef unsigned long long int u64;
typedef long long int s64;
// insert functions like isPrime, extEuclid, etc. here
bool isPrime(s64 n) {
if (n == 2)
return true;
if (n % 2 == 0)
return false;
for (s64 i=3;i*i<=n;i+=2)
if (n % i == 0)
return false;
return true;
}
s64 extEuclid(s64 a,s64 b,s64 &lastX,s64 &lastY) {
s64 x,y,q,tmp;
x = lastY = 0;
y = lastX = 1;
while (b != 0) {
q = a / b;
tmp = a % b;
a = b;
b = tmp;
tmp = lastX - q * x;
lastX = x;
x = tmp;
tmp = lastY - q * y;
lastY = y;
y = tmp;
}
return a;
}
// functions that aren't completed yet
void doEncrypt(s64 n,s64 e,char *inFileName,char *outFileName) {
cout << "In doEncrypt(" << n << ',' << e << ',' // ./project3 -e n... e... junkfile junk.enc
<< inFileName << ',' << outFileName << ")\n"; // ./project3 -d n... d... junk.enc test if(!inFile)
// open files and make sure that succeeds
// loop forever
// read three characters. if first read fails, stop loop
// if second and/or third fail, use 0 for them
// use the .get() method
// convert to number (m), see problem spex
// compute M = (m^e) % n. use modExp(m,e,n)
// output M with a space or \n after
// end of loop
// close the files
}
void doDecrypt(s64 n,s64 d,char *inFileName,char *outFileName) {
cout << "In doDecrypt(" << n << ',' << d << ','
<< inFileName << ',' << outFileName << ")\n";
// open files and make sure that succeeds
// loop forever
// read M from file
// compute m = (M^d) % n. use modExp(M,d,n)
// extract three characters from m.
// output any of them that are not 0
// end of loop
// close the files
}
void keyGen(s64 &n,s64 &e,s64 &d) {
s64 p,q,f,x,y;
// randomly choose p
do {
p = rand() % 61423 + 4099;
} while (!isPrime(p));
// randomly choose q
do {
q = rand() % 61423 + 4099;
} while (!isPrime(q));
// compute n
n = p * q;
// compute f
f = (p - 1) * (q - 1);
// randomly choose e
do {
e = rand() % 61423 + 4099;
} while (extEuclid(e,f,x,y) != 1);
// compute d
extEuclid(e,f,d,y);
cout << "In keyGen()\n";
// to test this...
// output p,q,n,e,f,d
cout << "Testing...\np = " << p << "\nq = " << q
<< "\nn = " << n << "\ne = " << e << "\nf = "
<< f << "\nd = " << d << endl;
// p and q should be random, prime and between 4099 and 65521
// n should be p * q
// f should be (p-1)*(q-1)
// e should be random, between 4096 and 65535 and gcd(e,f) == 1
// (d*e)%f should be 1
}
// functions that are done
bool validateInt(char *str,s64 &n) {
int i;
for (i=0;str[i]!=0;i++) // look to make sure all are digits
if (!isdigit(str[i])) // no digit? Stop now.
break;
if (str[i] == 0) { // if we make it to the end, good
n = strtoul(str,NULL,10);
return true;
} else // otherwise, not valid
return false;
}
void doKeyGen(void) {
s64 n,e,d;
keyGen(n,e,d);
cout << " Public key: " << n << " " << e << endl;
cout << "Private key: " << n << " " << d << endl;
}
int main(int argc,char *argv[]) {
bool optionsOk = false;
s64 n,e,d;
srand(time(NULL));
if (argc == 2) { // looking for -k
if (argv[1][0] == '-' && argv[1][1] == 'k') {
doKeyGen();
optionsOk = true;
}
}
if (argc == 6) { // looking for -d or -e
if (argv[1][0] == '-') {
if (argv[1][1] == 'e') {
if (validateInt(argv[2],n) && validateInt(argv[3],e)) {
doEncrypt(n,e,argv[4],argv[5]);
optionsOk = true;
}
}
if (argv[1][1] == 'd') {
if (validateInt(argv[2],n) && validateInt(argv[3],d)) {
doDecrypt(n,d,argv[4],argv[5]);
optionsOk = true;
}
}
}
}
if (!optionsOk) {
cout << "Usage: project3 -k\n"
" project3 -e public-n public-e input-file output-file\n"
" project3 -d public-n private-d input-file output-file\n";
}
return 0;
}
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