prepare for encrypted hdr epk2/epk3

src/formats.rs

@@ -8,3 +8,4 @@ pub mod msd10;
 pub mod msd11;
 pub mod sddl_sec;
 pub mod epk2;
+pub mod epk;

src/formats/epk.rs

@@ -0,0 +1,55 @@
+use std::fs::File;
+
+use crate::common;
+use crate::formats;
+
+pub fn is_epk_file(file: &File) -> bool {
+    let versions = common::read_file(&file, 1712, 36).expect("Failed to read from file.");
+
+    if check_epk_version(&versions).is_some() {
+        true
+    } else {
+        false
+    }
+}
+
+fn check_epk_version(versions: &[u8]) -> Option<String> {
+    let epk2_pattern = "____XXXX.XXXX.XXXX__XX.XX.XXX_______";
+    let epk3_pattern = "____X.X.X___________X.X.X___________";
+
+    if match_with_pattern(&versions, epk2_pattern) {
+        Some("epk2".to_string())
+    } else if match_with_pattern(&versions, epk3_pattern) {     
+        Some("epk3".to_string())
+    } else {
+        None
+    }
+}
+
+fn match_with_pattern(data: &[u8], pattern: &str) -> bool {
+    for (&b, p) in data.iter().zip(pattern.bytes()) {
+        match p {
+            b'_' if b != 0x00 => return false,
+            b'X' if !b.is_ascii_digit() => return false,
+            b'.' if b != b'.' => return false,
+            _ if p != b'_' && p != b'X' && p != b'.' => return false,
+            _ => {}
+        }
+    }
+    true
+}
+
+pub fn extract_epk(file: &File, output_folder: &str) -> Result<(), Box<dyn std::error::Error>> {
+
+    let versions = common::read_file(&file, 1712, 36)?;
+    let epk_version = check_epk_version(&versions);
+    
+    if epk_version == Some("epk2".to_string()) {
+        println!("EPK2 detected!\n");
+        formats::epk2::extract_epk2(file, output_folder)?;
+    } else if epk_version == Some("epk3".to_string()) {
+        println!("EPK3 detected! Not supported yet.");
+    }
+
+    Ok(())
+}

src/formats/epk2.rs

@@ -38,7 +38,17 @@ fn decrypt_aes128_ecb(key: &[u8], ciphertext: &[u8]) -> Result<Vec<u8>, Box<dyn
 }
 
 pub fn extract_epk2(mut file: &File, output_folder: &str) -> Result<(), Box<dyn std::error::Error>> {
-    let _epak = common::read_exact(&mut file, 4)?; // epak magic
+
+    file.seek(SeekFrom::Start(128))?;
+
+    //check if header is encrypted
+    let epak = common::read_exact(&mut file, 4)?; // epak magic
+    if epak == b"epak" {
+        println!("Header is not encrypted.");
+    } else {
+        println!("Header is encrypted. Not supported yet");
+        return Ok(());
+    }
 
     let file_size_bytes = common::read_exact(&mut file, 4)?;
     let file_size = u32::from_le_bytes(file_size_bytes.try_into().unwrap());
@@ -79,7 +89,14 @@ pub fn extract_epk2(mut file: &File, output_folder: &str) -> Result<(), Box<dyn
     }
 
     // Saturn7/BCM3556
-    let key = "2F2E2D2C2B2A29281716151413121110";
+    //let key = "2F2E2D2C2B2A29281716151413121110";
+
+    // new BCM35230
+    let key = "6856A0482475A8B41728A35474810203";
+
+    //mtk5369 - Mediatek GP4 - HE_DTV_GP4I_AFAAATAA
+    //let key = "7184C9C428D03C445188234D5A827196";
+
     let key_bytes = hex::decode(key)?;
 
     let mut signature_count = 0;

src/main.rs

@@ -71,10 +71,16 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
             println!("EPK1 file detected!");
             formats::epk1::extract_epk1(&file, &output_path)?;
         }
+        //epk2 with unencrypted header
         else if formats::epk2::is_epk2_file(&file) {
             println!("EPK2 file detected!");
             formats::epk2::extract_epk2(&file, &output_path)?;
         }
+        //epk with encrypted header - it can be epk2 or epk3 so we need to check
+        else if formats::epk::is_epk_file(&file) {
+            println!("EPK file detected!");
+            formats::epk::extract_epk(&file, &output_path)?;
+        }
         else if formats::pfl_upg::is_pfl_upg_file(&file) {
             println!("PFL UPG file detected!");
             formats::pfl_upg::extract_pfl_upg(&file, &output_path)?;