pfl_upg: change key detection ope, add some sony keys, add extraction of nested UPG

src/formats/pfl_upg/include.rs

@@ -2,29 +2,44 @@ use crate::utils::common;
 use binrw::BinRead;
 use aes::Aes256;
 use ecb::{Decryptor, cipher::{BlockDecryptMut, KeyInit, generic_array::GenericArray}};
+use crate::keys;
+use rsa::{RsaPublicKey, BigUint};
+
+pub fn try_find_key(sig: &[u8], ciphertext: &[u8]) -> Result<Option<(String, [u8; 32])>, Box<dyn std::error::Error>> {
+    let mut result: Option<(String, [u8; 32])> = None;
+
+    for (name, n_hex) in keys::PFLUPG {     
+        let n = BigUint::from_bytes_be(&hex::decode(n_hex)?);
+        let e = BigUint::from_bytes_be(&hex::decode("010001")?);
+        let pubkey = RsaPublicKey::new(n, e)?;
+
+        let sig_int = BigUint::from_bytes_le(&sig);
+        let dec_int = rsa::hazmat::rsa_encrypt(&pubkey, &sig_int)?;
+        let dec_sig = dec_int.to_bytes_le();
+
+        let aes_key = &dec_sig[20..52];
+        let dec_ciphertext = decrypt_aes256_ecb(aes_key.try_into().unwrap(), &ciphertext)?;
+        
+        //needs to start with null-termninated filename string
+        let end = match dec_ciphertext.iter().position(|&b| b == 0) {
+            Some(pos) => pos,
+            None => continue,       //there is no 0, continue
+        };
+        let fname = &dec_ciphertext[..end];
+        if fname.is_ascii() {       //is ascii filename
+            result = Some((name.to_string(), aes_key.try_into().unwrap()));
+            break
+        }
+    }
+
+    Ok(result)
+}
 
-pub static AUTO_FWS: &[(&str, &str)] = &[
-    ("Q5551", "q5551"),
-    ("Q5553", "q5551"),
-    ("Q554E", "q5551"),
-    ("Q554M", "q5551"),
-    ("QF1EU", "qf1eu"),
-    ("QF2EU", "qf1eu"),
-    ("Q591E", "q591e"),
-    ("Q522E", "q522e"),
-    ("Q582E", "q522e"),
-    ("Q5481", "q5481"),
-    ("Q5431", "q5431"),
-    ("Q5492", "q5492"),
-    ("S5551", "q5551"), //Sharp
-];
 
 type Aes256EcbDec = Decryptor<Aes256>;
 
-pub fn decrypt_aes256_ecb(key: &[u8], ciphertext: &[u8]) -> Result<Vec<u8>, Box<dyn std::error::Error>> {
-    let key_array: [u8; 32] = key.try_into()?;
-
-    let mut decryptor = Aes256EcbDec::new(&key_array.into());
+pub fn decrypt_aes256_ecb(key: [u8; 32], ciphertext: &[u8]) -> Result<Vec<u8>, Box<dyn std::error::Error>> {
+    let mut decryptor = Aes256EcbDec::new(&key.into());
     let mut buffer = ciphertext.to_vec();
 
     for chunk in buffer.chunks_exact_mut(16) {
@@ -38,7 +53,7 @@ pub fn decrypt_aes256_ecb(key: &[u8], ciphertext: &[u8]) -> Result<Vec<u8>, Box<
 #[derive(BinRead)]
 pub struct Header {
     _magic_bytes: [u8; 8],
-    pub header_size: u32,
+    pub header_size: u32,   //data start
     pub data_size: u32,
 	_crc32: u32,
 	pub mask: u32,
@@ -73,7 +88,7 @@ impl FileHeader {
     pub fn has_extended_name(&self) -> bool {
         (self.attributes[2] & (1 << 7)) != 0
     }
-    pub fn _is_package(&self) -> bool {
-        (self.attributes[3] & (1 << 1)) != 0
+    pub fn is_package(&self) -> bool {
+        (self.attributes[3] & (1 << 2)) != 0
     }
 }