Add keycode application func

src/main.rs

@@ -1,6 +1,9 @@
 use std::io::{Read, Seek, SeekFrom};
 use std::fs::File;
 use std::default::Default;
+use std::mem::transmute;
+
+use byteorder::{ReadBytesExt, LittleEndian};
 
 #[derive(Default)]
 pub struct NDSCartridgeHeader {
@@ -45,19 +48,62 @@ pub fn blowfish_nds(v: &mut u64, kbuf: &[u32], enc: bool) {
     }
 
     // Swap + P-array[16,17] XOR
-    *v = ((x ^ kbuf[koff]) as u64) | (((y ^ kbuf[1 + koff]) as u64) << 32); 
+    *v = ((y ^ kbuf[koff]) as u64) | (((x ^ kbuf[1 + koff]) as u64) << 32);
+}
+
+/* Applies a series of arbitrary manipulations on the P-array and S-boxes 
+   depending on the title key. 
+*/
+pub fn apply_keycode(tk: &mut [u32; 3], kbuf: &mut [u32]) {
+    // The two encrypt steps overlap each other
+    let tk0ptr = unsafe { transmute::<&mut u32, &mut u64>(&mut tk[0]) };
+    let tk1ptr = unsafe { transmute::<&mut u32, &mut u64>(&mut tk[1]) };
+    let mut scratch: u64 = 0;
+
+    blowfish_nds(tk1ptr, kbuf, true);
+    blowfish_nds(tk0ptr, kbuf, true);
+
+    for i in 0..12 {
+        kbuf[i] = kbuf[i] ^ kbuf[i % 2].swap_bytes();
+    }
+
+    for i in (0..131).step_by(2) {
+        blowfish_nds(&mut scratch, kbuf, true);
+        kbuf[i]     = unsafe { *transmute::<*const u64, *const u32>(&scratch as *const u64).offset(1) }; 
+        kbuf[i + 1] = unsafe { *transmute::<*const u64, *const u32>(&scratch as *const u64) };
+    }
+}
+
+pub fn load_encr_data<R: Read + Seek>(encr_data: &mut R) -> Result<[u32; 262], &'static str> {
+    // let data_len = encr_data.seek(SeekFrom::End(0)).map_err(|_| { "Seek failed on encryption binary." })?;
+    encr_data.seek(SeekFrom::Start(0)).map_err(|_| { "Seek failed on encryption binary." })?;
+    
+    let mut contents: [u32; 262] = [0; 262];
+    for i in &mut contents {
+        *i = encr_data.read_u32::<LittleEndian>().unwrap();
+    }
+
+    Ok(contents)
 }
 
 fn main() {
     let mut ndsfile = File::open("pokemon.nds").unwrap();
-    let encr_data = File::open("encr_data.bin").unwrap();
+    let mut encr_data = File::open("encr_data.bin").unwrap();
 
-    let titlecode = NDSCartridgeHeader::parse_nds(&mut ndsfile).gamecode;
-    let titlecode4: u32 = u32::from_le_bytes(titlecode);
+    let mut encr = load_encr_data(&mut encr_data).unwrap();
 
-    let keycode: [u32; 3] = [
+    let ndshdr = NDSCartridgeHeader::parse_nds(&mut ndsfile);
+    let titlestr: String = String::from_utf8_lossy(&ndshdr.gametitle).into_owned();
+    let titlecode4: u32 = u32::from_le_bytes(ndshdr.gamecode);
+
+    let mut keycode: [u32; 3] = [
         titlecode4,
         titlecode4 >> 1,
         titlecode4 << 1,
     ];
+
+    apply_keycode(&mut keycode, &mut encr);
+
+    println!("Game title: {}", titlestr);
+    println!("Game code: {:#06x}", titlecode4);
 }