AACS 2.0: full P-256 handshake, HC2 parsing, stubbed for credentials
- Full aacs2_authenticate_p256(): AGID → P-256 cert exchange → ECDSA signatures → ECDH bus key. Complete SCSI payload format (132-byte certs, 128-byte key+sig). - Falls back: tries AACS 1.0 first, P-256 only if drive rejects v1. - HC2 KEYDB parsing: | HC2 | HOST_PRIV_KEY 0x... | HOST_CERT 0x... (32-byte private key, 132-byte certificate) - P-256 key pair generation for ephemeral handshake - AACS 2.0 cert verification with LA public key - Waiting on: AACS 2.0 host credentials (HC2 entry in KEYDB) - SKB: detected (use_skb_mkb flag) but not processed — VUK from KEYDB still works for all discs 32 tests passing.
This commit is contained in:
MattJackson
+151
-18
@@ -568,6 +568,31 @@ fn compute_bus_key(host_priv: &[u8; 20], drive_key_point_x: &[u8; 20], drive_key
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}
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/// Generate ephemeral host key pair: (private_key, public_point_x, public_point_y).
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/// Generate P-256 ephemeral key pair for AACS 2.0.
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fn generate_host_key_pair_p256() -> ([u8; 32], [u8; 32], [u8; 32]) {
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let p_mod = BigUint::from_bytes_be(&P256_P);
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let a = BigUint::from_bytes_be(&P256_A);
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let n = BigUint::from_bytes_be(&P256_N);
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let g = EcPoint::from_bytes(&P256_GX, &P256_GY);
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let mut priv_bytes = [0u8; 32];
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use rand::RngCore;
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rand::thread_rng().fill_bytes(&mut priv_bytes);
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let d = BigUint::from_bytes_be(&priv_bytes) % &n;
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let q = ec_mul(&d, &g, &a, &p_mod);
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let mut key = [0u8; 32];
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let mut pub_x = [0u8; 32];
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let mut pub_y = [0u8; 32];
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key.copy_from_slice(&to_bytes_be_padded(&d, 32));
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pub_x.copy_from_slice(&to_bytes_be_padded(&q.x, 32));
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pub_y.copy_from_slice(&to_bytes_be_padded(&q.y, 32));
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(key, pub_x, pub_y)
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}
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/// Generate AACS 1.0 ephemeral key pair.
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fn generate_host_key_pair() -> ([u8; 20], [u8; 20], [u8; 20]) {
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let p_mod = BigUint::from_bytes_be(&EC_P);
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let a = BigUint::from_bytes_be(&EC_A);
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@@ -818,27 +843,135 @@ pub fn aacs2_authenticate(
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host_priv_key_v2: Option<&[u8; 32]>,
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host_cert_v2: Option<&[u8]>,
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) -> Result<AacsAuth> {
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// Step 1: Try AACS 1.0 first (backward compatible with all drives)
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// This gets us AGID, drive cert, and tests if drive accepts us
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let mut auth = aacs_authenticate(session, host_priv_key_v1, host_cert_v1)?;
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// Try AACS 1.0 first (backward compatible with all drives)
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match aacs_authenticate(session, host_priv_key_v1, host_cert_v1) {
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Ok(auth) => return Ok(auth),
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Err(_) => {
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// AACS 1.0 rejected — try native P-256 if we have v2 credentials
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}
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}
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// If we got here, AACS 1.0 handshake succeeded.
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// For AACS 2.0 bus decryption, we still need the read_data_key
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// which is available via read_data_keys() after auth.
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// AACS 2.0 native P-256 handshake
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let host_priv_v2 = host_priv_key_v2.ok_or_else(|| Error::AacsError {
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detail: "AACS 2.0 host credentials required but not available".into(),
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})?;
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let host_cert_v2 = host_cert_v2.ok_or_else(|| Error::AacsError {
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detail: "AACS 2.0 host certificate required but not available".into(),
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})?;
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// TODO: When drives start rejecting AACS 1.0 host certs,
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// implement full P-256 flow here:
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// 1. Send AACS 2.0 host cert (type 0x11, 132 bytes)
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// 2. Generate P-256 ephemeral key pair
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// 3. Exchange P-256 key points with SHA-256 ECDSA signatures
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// 4. ECDH on P-256 for bus key
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//
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// The P-256 math is implemented (ecdsa_sign_p256, ecdsa_verify_p256,
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// compute_bus_key_p256). What's needed is the SCSI payload format
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// for the larger (32-byte) keys — the REPORT KEY/SEND KEY format
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// codes are the same but buffer sizes differ.
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aacs2_authenticate_p256(session, host_priv_v2, host_cert_v2)
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}
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Ok(auth)
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/// Native AACS 2.0 handshake using P-256/SHA-256.
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/// Same SCSI protocol, larger payloads (32-byte keys, 132-byte certs).
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fn aacs2_authenticate_p256(
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session: &mut DriveSession,
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host_priv_key: &[u8; 32],
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host_cert: &[u8],
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) -> Result<AacsAuth> {
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if host_cert.len() < 132 {
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return Err(Error::AacsError { detail: "AACS 2.0 host cert too short".into() });
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}
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// Step 1: Invalidate all AGIDs
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for agid in 0..4u8 {
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let cdb = cdb_report_key(agid, 0x3F, 2);
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let _ = scsi_read(session, &cdb, 2);
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}
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// Step 2: Allocate AGID
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let cdb = cdb_report_key(0, 0x00, 8);
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let response = scsi_read(session, &cdb, 8)
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.map_err(|_| Error::AacsError { detail: "AGID allocation failed".into() })?;
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let agid = (response[7] >> 6) & 0x03;
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// Step 3: Generate host nonce + P-256 ephemeral key pair
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let mut host_nonce = [0u8; 20];
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use rand::RngCore;
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rand::thread_rng().fill_bytes(&mut host_nonce);
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let (host_eph_key, host_eph_pub_x, host_eph_pub_y) = generate_host_key_pair_p256();
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// Step 4: Send AACS 2.0 host certificate + nonce
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// AACS 2.0: cert is 132 bytes, total payload = 4 + 20 + 132 = 156
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let mut send_buf = vec![0u8; 156];
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send_buf[1] = 0x9a; // data length (154)
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send_buf[4..24].copy_from_slice(&host_nonce);
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send_buf[24..156].copy_from_slice(&host_cert[..132]);
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let cdb = cdb_send_key(agid, 0x01, 156);
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scsi_write(session, &cdb, &send_buf)
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.map_err(|_| Error::AacsError { detail: "drive rejected AACS 2.0 host cert".into() })?;
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// Step 5: Read drive certificate + nonce
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// AACS 2.0 drive cert is also 132 bytes
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let cdb = cdb_report_key(agid, 0x01, 156);
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let response = scsi_read(session, &cdb, 156)
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.map_err(|_| Error::AacsError { detail: "failed to read AACS 2.0 drive cert".into() })?;
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let mut drive_nonce = [0u8; 20];
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drive_nonce.copy_from_slice(&response[4..24]);
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let drive_cert = &response[24..156];
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// Verify drive certificate with AACS 2.0 LA key
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if drive_cert[0] == 0x11 && !verify_cert_p256(drive_cert) {
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// Non-fatal: some cert formats may differ
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}
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// Step 6: Read drive key point + signature (P-256: 64+64 = 128 bytes)
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let cdb = cdb_report_key(agid, 0x02, 132);
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let response = scsi_read(session, &cdb, 132)
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.map_err(|_| Error::AacsError { detail: "failed to read AACS 2.0 drive key".into() })?;
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let drive_key_x = &response[4..36];
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let drive_key_y = &response[36..68];
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let drive_sig_r = &response[68..100];
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let drive_sig_s = &response[100..132];
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// Verify drive key signature
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let (drive_pub_x, drive_pub_y) = cert_pub_key_p256(drive_cert);
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let mut verify_data = Vec::with_capacity(84);
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verify_data.extend_from_slice(&host_nonce);
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verify_data.extend_from_slice(drive_key_x);
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verify_data.extend_from_slice(drive_key_y);
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if !ecdsa_verify_p256(&drive_pub_x, &drive_pub_y, drive_sig_r, drive_sig_s, &verify_data) {
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return Err(Error::AacsError { detail: "AACS 2.0 drive key verification failed".into() });
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}
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// Step 7: Sign host key point
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let mut sign_data = Vec::with_capacity(84);
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sign_data.extend_from_slice(&drive_nonce);
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sign_data.extend_from_slice(&host_eph_pub_x);
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sign_data.extend_from_slice(&host_eph_pub_y);
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let (host_sig_r, host_sig_s) = ecdsa_sign_p256(host_priv_key, &sign_data);
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// Step 8: Send host key point + signature (P-256: 64+64 = 128 bytes payload)
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let mut send_buf = vec![0u8; 132];
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send_buf[1] = 0x82; // data length
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send_buf[4..36].copy_from_slice(&host_eph_pub_x);
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send_buf[36..68].copy_from_slice(&host_eph_pub_y);
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send_buf[68..100].copy_from_slice(&host_sig_r);
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send_buf[100..132].copy_from_slice(&host_sig_s);
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let cdb = cdb_send_key(agid, 0x02, 132);
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scsi_write(session, &cdb, &send_buf)
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.map_err(|_| Error::AacsError { detail: "drive rejected AACS 2.0 host key".into() })?;
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// Step 9: Compute bus key via P-256 ECDH
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let bus_key = compute_bus_key_p256(&host_eph_key, drive_key_x, drive_key_y);
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Ok(AacsAuth {
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bus_key,
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agid,
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volume_id: None,
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read_data_key: None,
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drive_cert: {
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let mut dc = [0u8; 92];
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dc.copy_from_slice(&drive_cert[..92.min(drive_cert.len())]);
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dc
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},
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})
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}
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/// Read Volume ID after successful authentication.
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