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#include "rc4.h"
char* rc4_getPassword(void) {
unsigned char* pass = malloc(PASS_MAX + 1);
if (pass == NULL) {
fprintf(stderr, "malloc() failed\n");
return NULL;
}
initscr();
noecho(); // Doesn't echo chars when typed
unsigned int c, i;
do {
printw("Enter Password (32 character max): ");
memset(pass, '\0', PASS_MAX + 1);
i = 0, c = 0;
while (c != '\n' && (c = (unsigned) getch())) {
if (c != BACKSPACE) {
pass[i] = (char) c;
i++;
if (i > PASS_MAX) { // Breaks loop if more than max
c = '\n';
printw("\n");
}
} else if (i > 0) // If backspace
pass[i - 1] = '\0';
}
} while (i > PASS_MAX);
clear();
endwin();
return (char*) pass;
}
void rc4_key_exchange(int keySchedule[KEY_SCHEDULE_LENGTH], char* key) {
size_t len = strlen(key);
int j = 0;
for (int i = 0; i < KEY_SCHEDULE_LENGTH; i++)
keySchedule[i] = i;
int temp;
for (int i = 0; i < KEY_SCHEDULE_LENGTH; i++) {
j = (j + keySchedule[i] + key[i % len]) % KEY_SCHEDULE_LENGTH;
temp = keySchedule[i];
keySchedule[i] = keySchedule[j];
keySchedule[j] = temp;
}
}
char* rc4_prga(int keySchedule[KEY_SCHEDULE_LENGTH], size_t len) {
int i = 0, j = 0, temp;
char* output = malloc(len);
if (output == NULL) {
fprintf(stderr, "malloc() failed\n");
return NULL;
}
for (int k = 0; k < (int) len; k++) {
i = (i + 1) % KEY_SCHEDULE_LENGTH;
j = (j + keySchedule[i]) % KEY_SCHEDULE_LENGTH;
temp = keySchedule[i];
keySchedule[i] = keySchedule[j];
keySchedule[j] = temp;
output[k] = (unsigned char) keySchedule[(keySchedule[i] + keySchedule[j]) % KEY_SCHEDULE_LENGTH];
}
return output;
}
void rc4_execute(char* output, String* pString) {
for (int i = 0; i < (int) pString->len; i++)
output[i] ^= pString->data[i];
}
char* rc4_encode_string(String* pString, char* password){
int keySchedule[256];
rc4_key_exchange(keySchedule, password);
char* output = rc4_prga(keySchedule, pString->len);
rc4_execute(output, pString);
return output;
}
String* rc4_get_crypted_string(String* input_pString, char* password, int option) {
String* output_pString = NULL;
int free_pw = (password == NULL);
Json* jobj = json_tokener_parse(input_pString->data);
if (option == ENCRYPT && jobj == NULL) // If trying to encrypt an encrypted portfolio
printf("Your portfolio is already encrypted.\n");
else if (option == DECRYPT && jobj != NULL) // If trying to decrypt an unencrypted portfolio
printf("Your portfolio isn't encrypted.\n");
else {
if (password == NULL) { // Get password if not provided
password = rc4_getPassword();
if (option == ENCRYPT) { // When encrypting, ask to enter pw twice to make sure
printf("You will be asked to enter your password again to make sure the entries match.\n");
sleep(2);
char* passwordCheck = rc4_getPassword();
if (strcmp(password, passwordCheck) != 0) {
printf("Passwords do not match!\n");
free(password);
free(passwordCheck);
json_object_put(jobj);
return NULL;
}
free(passwordCheck);
}
}
output_pString = string_init(); // Set ouput string to en/decrypted data
free(output_pString->data);
output_pString->data = rc4_encode_string(input_pString, password);
output_pString->len = input_pString->len;
if (option == DECRYPT) {
json_object_put(jobj);
output_pString->data = realloc(output_pString->data, output_pString->len + 1);// Realloc to add null terminator for json parsing
if (output_pString->data == NULL) { // Dealing with len is annoying so it's easier to just realloc
fprintf(stderr, "realloc() failed\n");
exit(EXIT_FAILURE);
}
output_pString->data[output_pString->len] = '\0'; // Null terminate string for parsing
jobj = json_tokener_parse(output_pString->data);
if (jobj == NULL) { // If after decrypting, the portfolio is not JSON formatted,
printf("Wrong password!\n"); // then it's the wrong password
free(password);
string_destroy(&output_pString);
return NULL;
}
}
if (free_pw) { // If being called from main
free(password);
if (option == ENCRYPT)
printf("Successfully encrypted your portfolio.\n");
else printf("Successfully decrypted your portfolio.\n");
}
}
json_object_put(jobj);
return output_pString;
}
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