0.27.5 (step 2, Phase 1): expose AACS inputs (uk_ro, mkb) on AacsState

scan now stashes the raw Unit_Key_RO.inf + MKB bytes on AacsState (via
resolve_vid_only, the disable_keydb path), so an external key-resolver can
derive unit keys from a resolved VUK without re-reading the disc — the
foundation for moving lookup/derivation out of libfreemkv. Additive: the keydb
path is untouched, all existing constructors default the new fields empty.
584 lib tests green. Builds on the KeyOrigin rename + the Key/decrypt_with API.

src/disc/encrypt.rs

@@ -465,6 +465,8 @@ impl Disc {
             unit_keys: resolved.unit_keys,
             read_data_key,
             volume_id,
+            uk_ro: Vec::new(),
+            mkb: Vec::new(),
         })
     }
 
@@ -527,6 +529,8 @@ impl Disc {
             unit_keys: vec![(1, unit_key)],
             read_data_key: handshake.and_then(|h| h.read_data_key),
             volume_id: handshake.map(|h| h.volume_id).unwrap_or([0u8; 16]),
+            uk_ro: Vec::new(),
+            mkb: Vec::new(),
         })
     }
 
@@ -563,12 +567,12 @@ impl Disc {
             None => 1,
         };
         // MKB_RO is the correctly-sized copy; avoid reading the padded RW region.
-        let mkb_ver = udf_fs
+        let mkb_bytes = udf_fs
             .read_file(reader, "/AACS/MKB_RO.inf")
             .or_else(|_| udf_fs.read_file(reader, "/AACS/MKB_RW.inf"))
             .ok()
-            .as_deref()
-            .and_then(aacs::mkb_version);
+            .unwrap_or_default();
+        let mkb_ver = aacs::mkb_version(&mkb_bytes);
 
         tracing::warn!(
             target: "freemkv::disc",
@@ -590,6 +594,8 @@ impl Disc {
             unit_keys: vec![],
             read_data_key: handshake.and_then(|h| h.read_data_key),
             volume_id: handshake.map(|h| h.volume_id).unwrap_or([0u8; 16]),
+            uk_ro: uk_ro_data,
+            mkb: mkb_bytes,
         })
     }
 }

src/disc/mod.rs

@@ -893,6 +893,13 @@ pub struct AacsState {
     pub read_data_key: Option<[u8; 16]>,
     /// Volume ID (16 bytes) -- from SCSI handshake
     pub volume_id: [u8; 16],
+    /// Raw `Unit_Key_RO.inf` bytes (encrypted unit keys + CPS map). Stashed at
+    /// scan so an external resolver (key-resolver) can derive the unit keys
+    /// from a VUK without re-reading the disc. Empty when not captured.
+    pub uk_ro: Vec<u8>,
+    /// Raw MKB bytes (`MKB_RO.inf`). Stashed at scan so an external resolver can
+    /// walk it (device/processing key → media key). Empty when not captured.
+    pub mkb: Vec<u8>,
 }
 
 /// How AACS keys were resolved. Variants are ordered root-of-trust →
@@ -1555,7 +1562,9 @@ impl Disc {
                 unit_keys: keys,
                 read_data_key: None,
                 volume_id: [0u8; 16],
-            });
+            uk_ro: Vec::new(),
+            mkb: Vec::new(),
+        });
             // The prior resolution error (e.g. KeydbLoad) is now moot — we have
             // the decryption key. Clear it so callers don't treat the disc as
             // keyless on the stale error.
@@ -2833,6 +2842,8 @@ mod tests {
             unit_keys,
             read_data_key: None,
             volume_id: [0u8; 16],
+            uk_ro: Vec::new(),
+            mkb: Vec::new(),
         }
     }