[kwm] refactor: move Decipher new fn under struct

um_crypto/kuwo/src/lib.rs

@@ -43,19 +43,32 @@ impl fmt::Display for HeaderMagicBytes {
 
 pub const DATA_START_OFFSET: usize = 0x400;
 
-pub enum Cipher {
+pub enum Decipher {
     V1(CipherV1),
     V2(CipherV2),
 }
 
-impl Cipher {
+impl Decipher {
+    pub fn new<T: AsRef<[u8]>>(header: &Header, ekey: Option<T>) -> Result<Decipher> {
+        let cipher = match header.version {
+            1 => Decipher::V1(CipherV1::new(header.resource_id)),
+            2 => match ekey {
+                Some(ekey) => Decipher::V2(CipherV2::new_from_ekey(ekey)?),
+                None => Err(KuwoCryptoError::V2EKeyRequired)?,
+            },
+            version => Err(KuwoCryptoError::UnsupportedVersion(version as usize))?,
+        };
+
+        Ok(cipher)
+    }
+
     pub fn decrypt<T>(&self, data: &mut T, offset: usize)
     where
         T: AsMut<[u8]> + ?Sized,
     {
         match self {
-            Cipher::V1(cipher) => cipher.decrypt(data, offset),
-            Cipher::V2(cipher) => cipher.decrypt(data, offset),
+            Decipher::V1(cipher) => cipher.decrypt(data, offset),
+            Decipher::V2(cipher) => cipher.decrypt(data, offset),
         }
     }
 }
@@ -105,22 +118,6 @@ impl Header {
         })
     }
 
-    pub fn get_decipher<T>(&self, ekey: Option<T>) -> Result<Cipher>
-    where
-        T: AsRef<[u8]>,
-    {
-        let cipher = match self.version {
-            1 => Cipher::V1(CipherV1::new(self.resource_id)),
-            2 => match ekey {
-                Some(ekey) => Cipher::V2(CipherV2::new_from_ekey(ekey)?),
-                None => Err(KuwoCryptoError::V2EKeyRequired)?,
-            },
-            version => Err(KuwoCryptoError::UnsupportedVersion(version as usize))?,
-        };
-
-        Ok(cipher)
-    }
-
     /// Get the quality id
     /// Used for matching Android MMKV id.
     pub fn get_quality_id(&self) -> u32 {