Demo: xor-based encryption (2006)

If only I had published this earlier I would be rich

demos/enc.c

@@ -0,0 +1,127 @@
+/* enc.c Convert a string, each character into binary. Take "key"
+ * and convert to binary. xor character binary with key binary to make
+ * the new encrypted character. Key will be obtained through input.
+ * (c) 2006 Shaun Marquardt.
+ */
+
+#include <stdio.h>
+#include <stdlib.h> //exit //strtol
+#include <conio.h> //clrscr //getche
+#include <string.h> //strlen for htoa
+#include <ctype.h> //toupper for htoa
+
+#define TRUE 1
+#define FALSE !TRUE
+
+void htoa( char *input );
+long strtol(const char *s, char **endp, int base); //strtol is in stdlib.h
+
+int main(int argc, char *argv[])
+{
+	char input_str[100];
+	char key_str[100];
+	char enc_str[100];
+	char input_bits;
+	char key_bits;
+	char enc_bits[8];
+	char *bp;
+	int p = 0;
+
+	clrscr();
+	printf("Enter the string to be encrypted: ");
+	gets(input_str);
+
+   printf("\nDebug: input_str = %s",input_str);
+   
+	printf("\nEnter Encryption Key: ");
+	for(p=0; input_str[p] != NULL; p++)
+		key_str[p] = getche();
+
+   printf("\nDebug: key_str = %s",key_str);
+   
+	printf("\n\n========Encrypt.========\n\n");
+	sprintf(input_bits, "%ld", strtol(input_str, &bp, 2)); //ascii ->bin
+	sprintf(key_bits, "%ld", strtol(key_str, &bp, 2));
+
+   printf("\nDebug: input_bits = %s\n", input_bits);
+   printf("Debug: key_bits = %s\n", key_bits);
+	/* bitwise math-o-rama */
+	
+	for(p=0; input_bits[p] != NULL; p++)
+	{
+		if (input_bits[p] == key_bits[p])
+			enc_bits[p] = 1;
+
+		enc_bits[p] = 0;
+	}
+
+	sprintf(enc_str, "%ld", strtol(enc_bits, &bp, 16)); //bin ->hex
+
+	htoa(enc_str);
+	printf("\nDone. Press the enter key to exit the program.");
+	getch();
+	exit(0);
+}
+
+/* my stolen htoa (c) me */
+void htoa( char *input )
+{
+ unsigned char a;
+ char hex[5];
+ char buf[5];
+ int x = 0, col = 0;
+ int done;
+
+ hex[0] = '\0';
+
+ if( (strlen(input) % 2) != 0 )
+ {
+   printf("Hex characters must be entered in pairs.\n");
+   getch();
+   exit(1);
+ }
+ 
+ printf("Hex - \"%s\"\n",input);
+ printf("--== Output ==--\n\n");
+ printf("\"");
+
+ done = FALSE;
+ while(!done)
+ {
+   if(input[x] == '\0') //End of input, done.
+   {
+    printf("\"\n");
+    done = TRUE;
+    break;
+   }
+
+   if(input[x] == ' ') //Space character? Print out a space.
+   {
+    printf("%c", ' ');
+    x++;
+   }
+   
+   sprintf(hex, "%c%c", toupper(input[x]), toupper(input[x+1])); //Get Hex Char
+   x+=2;
+   
+   for(a=32;a<128;a++)
+   {                      //Go through list of characters
+    sprintf(buf, "%X",a);
+
+    if(!strcmp(buf, hex)) //Matching, print character
+     printf("%c",a);
+    else            //Not Matching, continue
+     continue;
+     
+    col++;
+    if(col >= 79)
+    {
+     col = 0;
+     printf("\n\r");
+    }
+    break;
+   } //end "a" for loop
+   
+ } //end while
+return;
+} //end htoa