refactor: unify qmc2 decrypt api

um_crypto/qmc/src/lib.rs

@@ -1,5 +1,9 @@
+use crate::v2_map::QMC2Map;
+use crate::v2_rc4::cipher::QMC2RC4;
+use anyhow::Result;
 use thiserror::Error;
 
+pub mod ekey;
 pub mod footer;
 pub mod v1;
 pub mod v2_map;
@@ -11,6 +15,36 @@ pub enum QmcCryptoError {
     QMCV2MapKeyEmpty,
 }
 
+pub enum QMCv2Cipher {
+    MapL(QMC2Map),
+    RC4(QMC2RC4),
+}
+
+impl QMCv2Cipher {
+    pub fn new<T>(key: T) -> Result<Self>
+    where
+        T: AsRef<[u8]>,
+    {
+        let key = key.as_ref();
+        let cipher = match key.len() {
+            0 => Err(QmcCryptoError::QMCV2MapKeyEmpty)?,
+            ..=300 => QMCv2Cipher::MapL(QMC2Map::new(key)?),
+            _ => QMCv2Cipher::RC4(QMC2RC4::new(key)),
+        };
+        Ok(cipher)
+    }
+
+    pub fn decrypt<T>(&self, data: &mut T, offset: usize)
+    where
+        T: AsMut<[u8]> + ?Sized,
+    {
+        match self {
+            QMCv2Cipher::MapL(cipher) => cipher.decrypt(data, offset),
+            QMCv2Cipher::RC4(cipher) => cipher.decrypt(data, offset),
+        }
+    }
+}
+
 #[cfg(test)]
 mod test {
     pub fn generate_key(len: usize) -> Vec<u8> {