Text asset decryption

.github/FUNDING.yaml

@@ -1,4 +1,5 @@
 github: nicks96432
+ko_fi: nicks96432
 patreon: nicks96432
 custom:
   - "https://www.paypal.me/nicks96432"

extract/Cargo.toml

@@ -11,6 +11,10 @@ version = "0.1.0"
 # For decoding ACB audio
 acb = { path = "../acb" }
 
+# For text asset decryption
+aes = "0.8.3"
+cbc = "0.1.2"
+
 # For reading numbers from binary data
 byteorder = "1.5.0"
 

extract/src/class/asset_bundle.rs

@@ -13,7 +13,7 @@ use rabex::read_ext::ReadUrexExt;
 use crate::utils::ReadAlignedExt;
 use crate::version::*;
 
-pub fn _construct_p_ptr<R, E>(
+pub(super) fn _construct_p_ptr<R, E>(
     reader: &mut R,
     serialized_file: &SerializedFile,
 ) -> Result<PPtr, Box<dyn Error>>
@@ -94,7 +94,7 @@ where
     Ok(asset_info)
 }
 
-pub fn _construct_asset_bundle<E>(
+pub(super) fn _construct_asset_bundle<E>(
     data: &[u8],
     serialized_file: &SerializedFile,
 ) -> Result<AssetBundle, Box<dyn Error>>

extract/src/class/sprite.rs

@@ -18,7 +18,7 @@ use crate::version::*;
 use super::asset_bundle::_construct_p_ptr;
 use super::mesh::{construct_sub_mesh, construct_vertex_data};
 
-pub fn _construct_sprite<E>(
+pub(super) fn _construct_sprite<E>(
     data: &[u8],
     serialized_file: &SerializedFile,
 ) -> Result<Sprite, Box<dyn Error>>

extract/src/class/text_asset.rs

@@ -6,19 +6,21 @@ use std::path::Path;
 use std::slice::from_raw_parts;
 use std::str::FromStr;
 
-use byteorder::BigEndian;
-use byteorder::ByteOrder;
-use byteorder::LittleEndian;
+use aes::cipher::block_padding::Pkcs7;
+use aes::cipher::inout::InOutBufReserved;
+use aes::cipher::{BlockDecryptMut, BlockEncryptMut, KeyIvInit};
+use aes::Aes192;
+use byteorder::{BigEndian, ByteOrder, LittleEndian};
+use cbc::{Decryptor, Encryptor};
 use rabex::files::SerializedFile;
 use rabex::objects::classes::TextAsset;
 use rabex::read_ext::ReadUrexExt;
 
-use crate::utils::ffmpeg;
-use crate::utils::ReadAlignedExt;
+use crate::utils::{ffmpeg, ReadAlignedExt};
 use crate::version::*;
 use crate::ExtractorArgs;
 
-pub fn _construct_text_asset<E>(
+pub(super) fn _construct_text_asset<E>(
     data: &[u8],
     serialized_file: &SerializedFile,
 ) -> Result<TextAsset, Box<dyn Error>>
@@ -85,3 +87,56 @@ where
         output_path,
     )
 }
+
+pub const MLTD_TEXT_PBKDF2_HMAC_SHA1_KEY: &[u8; 8] = b"Millicon";
+pub const MLTD_TEXT_PBKDF2_HMAC_SHA1_SALT: &[u8; 9] = b"DAISUL___";
+pub const MLTD_TEXT_PBKDF2_HMAC_SHA1_ROUNDS: u32 = 1000;
+
+#[rustfmt::skip]
+/// The AES-192-CBC key used to decrypt the text asset.
+/// 
+/// It is derived from [`MLTD_TEXT_PBKDF2_HMAC_SHA1_KEY`] and
+/// [`MLTD_TEXT_PBKDF2_HMAC_SHA1_SALT`] using PBKDF2-HMAC-SHA1, where
+/// the first 24 bytes of the derived key are used as the actual key.
+pub const MLTD_TEXT_DECRYPT_KEY: &[u8; 24] = &[
+    0xad, 0x3f, 0x0f, 0x89, 0xee, 0x51, 0xc5, 0x37,
+    0x73, 0x1f, 0x17, 0x96, 0xf7, 0x5c, 0x71, 0x84,
+    0x01, 0x61, 0x75, 0x6d, 0xa0, 0xd4, 0x86, 0xc9,
+];
+
+#[rustfmt::skip]
+/// The AES-192-CBC initialization vector used to decrypt the text asset.
+/// 
+/// It is derived from [`MLTD_TEXT_PBKDF2_HMAC_SHA1_KEY`] and
+/// [`MLTD_TEXT_PBKDF2_HMAC_SHA1_SALT`] using PBKDF2-HMAC-SHA1, where
+/// the last 16 bytes of the derived key are used as the actual IV.
+pub const MLTD_TEXT_DECRYPT_IV: &[u8; 16] = &[
+    0x4e, 0x40, 0xb3, 0x8a, 0xeb, 0xf1, 0xa8, 0x53,
+    0x12, 0x2c, 0x5f, 0xad, 0xcc, 0xa3, 0x68, 0x5d,
+];
+
+pub type MltdTextEncryptor = Encryptor<Aes192>;
+pub type MltdTextDecryptor = Decryptor<Aes192>;
+
+pub fn encrypt_text(text: &[u8]) -> Result<Vec<u8>, Box<dyn Error>> {
+    let encryptor =
+        MltdTextEncryptor::new(MLTD_TEXT_DECRYPT_KEY.into(), MLTD_TEXT_DECRYPT_IV.into());
+    let mut buf = text.to_owned();
+
+    let buf = InOutBufReserved::from_mut_slice(&mut buf, text.len()).map_err(|e| e.to_string())?;
+    let buf = encryptor.encrypt_padded_inout_mut::<Pkcs7>(buf).map_err(|e| e.to_string())?;
+
+    Ok(buf.to_owned())
+}
+
+pub fn decrypt_text(cipher: &[u8]) -> Result<Vec<u8>, Box<dyn Error>> {
+    let decryptor =
+        MltdTextDecryptor::new(MLTD_TEXT_DECRYPT_KEY.into(), MLTD_TEXT_DECRYPT_IV.into());
+    let mut buf = cipher.to_owned();
+
+    let buf = decryptor
+        .decrypt_padded_inout_mut::<Pkcs7>(buf.as_mut_slice().into())
+        .map_err(|e| e.to_string())?;
+
+    Ok(buf.to_owned())
+}

extract/src/class/texture_2d.rs

@@ -22,7 +22,7 @@ use crate::environment::Environment;
 use crate::utils::{ffmpeg, solve_puzzle, ReadAlignedExt};
 use crate::{version::*, ExtractorArgs};
 
-fn _construct_texture_2d<E>(
+pub(super) fn _construct_texture_2d<E>(
     data: &[u8],
     serialized_file: &SerializedFile,
 ) -> Result<Texture2D, Box<dyn Error>>

extract/src/environment.rs

@@ -5,7 +5,7 @@ use std::io::{Read, Seek, SeekFrom};
 use byteorder::{BigEndian, ReadBytesExt};
 use rabex::read_ext::ReadUrexExt;
 
-#[derive(Debug)]
+#[derive(Debug, Default)]
 pub struct Environment {
     /// resource data that loaded from bundles
     resources: HashMap<String, Vec<u8>>,
@@ -16,7 +16,7 @@ pub struct Environment {
 
 impl Environment {
     pub fn new() -> Self {
-        Self { resources: HashMap::new(), objects: HashMap::new() }
+        Self::default()
     }
 
     pub fn register_cab(&mut self, path: &str, buf: Vec<u8>) {