Encrypts & decrypts Yakuza Kiwami 2 saves (doesn't do checksum yet)

yakuza.c

#include <stdio.h>
#include <stdlib.h>

static const char Key[]  = "STarYZgr3DL11";
static const int  KeyLen = 13;

int main(int argc, char **argv)
{
	FILE *in,  *out;
	char *data;
	size_t sz;
	
	if (argc != 3)
	{
		printf("Usage: %s in.sav out.sav\n", argv[0]);
		return 0;
	}
	
	if ((in = fopen(argv[1], "rb")) == NULL)
	{
		perror("Error");
		return 1;
	}
	
	if ((out = fopen(argv[2], "wb")) == NULL)
	{
		perror("Error");
		fclose(in);
		return 1;
	}
	
	printf("Writing %s to %s...\n", argv[1], argv[2]);
	
	fseek(in, 0, SEEK_END);
	sz   = ftell(in);
	data = malloc(sz);
	rewind(in);
	fread(data, 1, sz, in);
	fclose(in);
	
	for (int i = 0; i < sz; i++)
		data[i] ^= Key[i % KeyLen];
	
	fwrite(data, 1, sz, out);
	
	free(data);
	fclose(out);
	
	puts("Done!");
	
	return 0;
}