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/*
* crypt.cpp
*
*
*/
#include "crypt.h"
#ifndef DEBUG
#define DEBUG
#endif
/* forward declaration of variables from crypt_args.h */
extern char *fname;
extern char *keyfname;
extern char *outfname;
struct rsakey_t
{
unsigned long e, d, n;
bool valid_rsa_tag;
};
/* parse pubkey xml file */
struct rsakey_t parse_key(FILE *file)
{
struct rsakey_t key = { 0, 0, 0};
key.valid_rsa_tag = false;
/* used for line reading */
size_t line_sz = 0;
char *line = NULL;
bool rsa_opening_tag = false;
bool rsa_closing_tag = false;
while (getline(&line, &line_sz, file) != -1)
{
if (strcmp(line, "<rsakey>\n") == 0)
rsa_opening_tag = true;
sscanf(line, "\t<dvalue>%lu</dvalue>\n", &key.d);
sscanf(line, "\t<evalue>%lu</evalue>\n", &key.e);
sscanf(line, "\t<nvalue>%lu</nvalue>\n", &key.n);
if (strcmp(line, "</rsakey>\n") == 0)
rsa_closing_tag = true;
}
if (rsa_opening_tag && rsa_closing_tag)
key.valid_rsa_tag = true;
if (line)
free(line);
return key;
}
int main(int argc, char **argv)
{
if (crypt_args(argc, argv) == 0)
cout << "read arguments successfully" << endl;
#ifdef DEBUG
printf("debug: filename = \"%s\"\n"
" key filename = \"%s\"\n"
" result filename = \"%s\"\n",
fname, keyfname, outfname);
#endif
/* open file for reading and writing */
FILE *fname_fl = fopen(fname, "r");
FILE *keyfname_fl = fopen(keyfname, "r");
FILE *outfname_fl = fopen(outfname, "w");
if (fname_fl == NULL) {
fprintf(stderr, "fopen: \"%s\", %s\n", fname, strerror(errno));
exit(EXIT_FAILURE);
}
if (keyfname_fl == NULL) {
fprintf(stderr, "fopen: \"%s\", %s\n", keyfname, strerror(errno));
exit(EXIT_FAILURE);
}
if (outfname_fl == NULL) {
perror("fopen");
exit(EXIT_FAILURE);
}
int mode = -1;
struct rsakey_t key = parse_key(keyfname_fl);
if (!key.valid_rsa_tag)
{
fprintf(stderr, "invalid key or invalid xml\n");
exit(EXIT_FAILURE);
}
else if (key.d == 0 && key.e && key.n)
{
cout << "public key (" << key.e << ", " << key.n
<< ") detected, will perform encryption" << endl;
mode = 0;
}
else if (key.e == 0 && key.d && key.n)
{
cout << "private key (" << key.d << ", " << key.n
<< ") detected, will perform decryption" << endl;
mode = 1;
}
else
{
fprintf(stderr, "could not determine mode (encryption/decryption)\n");
exit(EXIT_FAILURE);
}
if (mode == 0) /* encrypt */
{
char *line = NULL;
size_t len = 0;
ssize_t read;
unsigned int readin = 0;
BigUnsigned calc = 0;
string writeout;
const char *outstr = NULL;
while ((read = getline(&line, &len, fname_fl)) != -1)
{
sscanf(line, "%u\n", &readin);
printf("read in: \"%u\"", readin);
calc = modexp(BigUnsigned(readin), key.e, key.n);
writeout = bigIntegerToString(calc);
cout << ", encrypted: " << writeout << endl;
outstr = writeout.c_str();
fprintf(outfname_fl, "%s\n", outstr);
}
free(line);
}
else /* decrypt */
{
char *line = NULL;
size_t len = 0;
ssize_t read;
char readin[100];
BigUnsigned calc = 0;
BigInteger tmpbig = 0;
string writeout;
string tmpstr;
const char *outstr = NULL;
while ((read = getline(&line, &len, fname_fl)) != -1)
{
sscanf(line, "%s\n", readin);
printf("read in: \"%s\"", readin);
string tmpstr(readin);
tmpbig = stringToBigInteger(tmpstr);
calc = modexp(tmpbig, key.d, key.n);
writeout = bigIntegerToString(calc);
cout << ", decrypted: " << writeout << endl;
outstr = writeout.c_str();
fprintf(outfname_fl, "%s\n", outstr);
}
free(line);
}
fclose(fname_fl);
fclose(keyfname_fl);
fclose(outfname_fl);
return 0;
}
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