[kgm] feat #2: basic kgm support

um_crypto/kgm/src/lib.rs

@@ -0,0 +1,21 @@
+pub mod header;
+pub mod v2;
+mod v3;
+
+use thiserror::Error;
+
+#[derive(Debug, Error)]
+pub enum KugouError {
+    #[error("Header too small, need at least {0} bytes.")]
+    HeaderTooSmall(usize),
+
+    #[error("Unsupported key slot: {0}")]
+    UnsupportedKeySlot(u32),
+
+    #[error("Unsupported cipher version: {0}")]
+    UnsupportedCipherVersion(u32),
+}
+
+pub trait Decipher {
+    fn decrypt(&self, buffer: &mut [u8], offset: usize);
+}