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Revise the scramble() and unscramble() functions

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The scramble() and unscramble() functions now use a moving (incrementing)
key for the XOR encryption/decryption.  Also include a table of XOR keys
to use at random for encryption.
Revised the scramble() and unscramble() functions to use a moving
(incrementing) key for the XOR encryption/decryption.  Also generated a
table of XOR keys to use at random for encryption.
This commit is contained in:
John Zaitseff 2011-07-14 12:30:23 +10:00
parent 91d77f002c
commit 200f7cdf97
3 changed files with 30 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
src/game.c
View File

@ -35,7 +35,18 @@
* Module constants and macros *
************************************************************************/
#define GAME_BUFSIZE (1024) /* Buffer size for game save/load */
// Game loading and saving constants
#define GAME_BUFSIZE (1024)
static const int game_file_crypt_key[] = {
0x50, 0x52, 0x55, 0x59, 0x5A, 0x5C, 0x5F,
0x90, 0x92, 0x95, 0x99, 0x9A, 0x9C, 0x9F,
0xA0, 0xA2, 0xA5, 0xA9, 0xAA, 0xAC, 0xAF,
0xD0, 0xD2, 0xD5, 0xD9, 0xDA, 0xDC, 0xDF
};
#define GAME_FILE_CRYPT_KEY_SIZE (sizeof(game_file_crypt_key) / sizeof(int))
// Macros used in load_game()
@ -103,7 +114,7 @@
#define save_game_printf(_fmt, _var) \
{ \
snprintf(buf, GAME_BUFSIZE, _fmt "\n", _var); \
scramble(GAME_FILE_CRYPT_KEY, buf, GAME_BUFSIZE); \
scramble(crypt_key, buf, GAME_BUFSIZE); \
fprintf(file, "%s", buf); \
}
@ -484,6 +495,7 @@ void end_game (void)
}
// @@@ To be written
save_game(2);
}
@ -662,6 +674,7 @@ bool save_game (int num)
FILE *file;
int saved_errno;
struct stat statbuf;
int crypt_key;
int i, j, x, y;
char *p;
@ -673,6 +686,8 @@ bool save_game (int num)
err_exit("out of memory");
}
crypt_key = game_file_crypt_key[randi(GAME_FILE_CRYPT_KEY_SIZE)];
// Create the data directory, if needed
data_dir = data_directory();
if (data_dir != NULL) {
@ -731,7 +746,7 @@ bool save_game (int num)
// Write out the game file header and encryption key
fprintf(file, "%s\n" "%s\n", GAME_FILE_HEADER, GAME_FILE_API_VERSION);
fprintf(file, "%d\n", GAME_FILE_CRYPT_KEY);
fprintf(file, "%d\n", crypt_key);
// Write out various game variables
save_game_write_int(MAX_X);
@ -774,7 +789,7 @@ bool save_game (int num)
*p++ = '\n';
*p = '\0';
scramble(GAME_FILE_CRYPT_KEY, buf, GAME_BUFSIZE);
scramble(crypt_key, buf, GAME_BUFSIZE);
fprintf(file, "%s", buf);
}

1
src/trader.h
View File

@ -38,7 +38,6 @@
#define GAME_FILE_HEADER PACKAGE_NAME " Saved Game"
#define GAME_FILE_API_VERSION "7.0" /* For game loads and saves */
#define GAME_FILE_SENTINEL (42)
#define GAME_FILE_CRYPT_KEY (0xAA)
/************************************************************************

38
src/utils.c
View File

@ -323,18 +323,18 @@ extern int randi (int limit)
char *scramble (int key, char *buf, int bufsize)
{
int i;
char c, e;
if ((buf != NULL) && (key != 0)) {
char *p = buf;
unsigned char k = ~key;
int i;
for (i = 0; (i < bufsize) && (*p != '\0'); i++, k++, p++) {
char c = *p;
char r = c ^ k; // Simple encryption: XOR on a moving key
if (key != 0) {
key = (~ key) & 0xFF;
for (i = 0; (i < bufsize) && (buf[i] != '\0'); i++) {
c = buf[i];
e = c ^ key; // Simple encryption: XOR!
if ((c != '\r') && (c != '\n')
&& (e != '\r') && (e != '\n') && (e != '\0')) {
buf[i] = e;
if ((c != '\r') && (c != '\n') &&
(r != '\r') && (r != '\n') && (r != '\0')) {
*p = r;
}
}
}
@ -360,21 +360,5 @@ char *scramble (int key, char *buf, int bufsize)
char *unscramble (int key, char *buf, int bufsize)
{
int i;
char c, d;
if (key != 0) {
key = (~ key) & 0xFF;
for (i = 0; (i < bufsize) && (buf[i] != '\0'); i++) {
c = buf[i];
d = c ^ key; // Simple decryption: XOR!
if ((c != '\r') && (c != '\n')
&& (d != '\r') && (d != '\n') && (d != '\0')) {
buf[i] = d;
}
}
}
return buf;
return scramble(key, buf, bufsize);
}