Support multiple host certs, expose handshake_error on AacsState

- host_cert: Option → host_certs: Vec (try all until one succeeds)
- handshake_error field shows why auth failed (e.g. cert rejected/revoked)

src/aacs/handshake.rs

@@ -1190,7 +1190,7 @@ mod tests {
         if !keydb_path.exists() { return; }
 
         let db = crate::aacs::KeyDb::load(&keydb_path).unwrap();
-        if let Some(hc) = &db.host_cert {
+        if let Some(hc) = db.host_certs.first() {
             let valid = verify_cert(&hc.certificate);
             eprintln!("Host cert verification: {}", if valid { "PASS" } else { "FAIL" });
             // Note: our cert is revoked but should still have valid LA signature

src/aacs/mod.rs

@@ -27,7 +27,7 @@ pub struct KeyDb {
     /// Processing keys (pre-computed media keys for specific MKB versions)
     pub processing_keys: Vec<[u8; 16]>,
     /// Host certificate + private key for SCSI authentication
-    pub host_cert: Option<HostCert>,
+    pub host_certs: Vec<HostCert>,
     /// Per-disc VUK entries indexed by disc hash (hex lowercase)
     pub disc_entries: HashMap<String, DiscEntry>,
 }
@@ -105,7 +105,7 @@ impl KeyDb {
         let mut db = KeyDb {
             device_keys: Vec::new(),
             processing_keys: Vec::new(),
-            host_cert: None,
+            host_certs: Vec::new(),
             disc_entries: HashMap::new(),
         };
 
@@ -135,7 +135,7 @@ impl KeyDb {
 
             // Host Certificate (AACS 2.0)
             if line.starts_with("| HC2") {
-                if let Some(ref mut hc) = db.host_cert {
+                if let Some(hc) = db.host_certs.last_mut() {
                     if let Some((pk, cert)) = Self::parse_host_cert_v2(line) {
                         hc.private_key_v2 = Some(pk);
                         hc.certificate_v2 = Some(cert);
@@ -146,7 +146,9 @@ impl KeyDb {
 
             // Host Certificate (AACS 1.0)
             if line.starts_with("| HC") {
-                db.host_cert = Self::parse_host_cert(line);
+                if let Some(hc) = Self::parse_host_cert(line) {
+                    db.host_certs.push(hc);
+                }
                 continue;
             }
 
@@ -1342,7 +1344,7 @@ mod tests {
 
         assert_eq!(db.device_keys.len(), 4);
         assert_eq!(db.processing_keys.len(), 3);
-        assert!(db.host_cert.is_some());
+        assert!(!db.host_certs.is_empty());
         assert!(db.disc_entries.len() > 170000);
 
         // Look up Dune: Part Two

src/disc.rs

@@ -322,6 +322,8 @@ pub struct AacsState {
     pub read_data_key: Option<[u8; 16]>,
     /// Volume ID (16 bytes) -- from SCSI handshake
     pub volume_id: [u8; 16],
+    /// Handshake error code if authentication failed (None = no HC, or success)
+    pub handshake_error: Option<crate::error::Error>,
 }
 
 /// How AACS keys were resolved.
@@ -567,11 +569,13 @@ impl Disc {
         // AACS SCSI handshake — get Volume ID (and read data key for AACS 2.0)
         let mut volume_id = [0u8; 16];
         let mut read_data_key = None;
+        let mut handshake_error = None;
 
-        if let Some(ref hc) = keydb.host_cert {
-            if let Ok(mut auth) = aacs::handshake::aacs_authenticate(
+        for hc in &keydb.host_certs {
+            match aacs::handshake::aacs_authenticate(
                 session, &hc.private_key, &hc.certificate,
             ) {
+                Ok(mut auth) => {
                     // Read Volume ID (needed for MK → VUK derivation)
                     if let Ok(vid) = aacs::handshake::read_volume_id(session, &mut auth) {
                         volume_id = vid;
@@ -581,6 +585,13 @@ impl Disc {
                     if let Ok((rdk, _wdk)) = aacs::handshake::read_data_keys(session, &mut auth) {
                         read_data_key = Some(rdk);
                     }
+
+                    handshake_error = None;
+                    break;
+                }
+                Err(e) => {
+                    handshake_error = Some(e);
+                }
             }
         }
 
@@ -609,6 +620,7 @@ impl Disc {
             unit_keys: resolved.unit_keys,
             read_data_key,
             volume_id,
+            handshake_error,
         })
     }