feat(tdx): add TDX RTMR extension support with UEFI marker

- Added `UEFI_MARKER_DIGEST_BYTES` constant for TDX RTMR extension.
- Implemented RTMR3 extension in `tee-key-preexec` for TDX attestation flow.
- Updated `rtmr-calc` to use `UEFI_MARKER_DIGEST_BYTES` for RTMR1 extension.

Signed-off-by: Harald Hoyer <harald@matterlabs.dev>

crates/teepot/src/tdx/rtmr.rs

@@ -1,10 +1,22 @@
 // SPDX-License-Identifier: Apache-2.0
-// Copyright (c) 2024 Matter Labs
+// Copyright (c) 2024-2025 Matter Labs
 
 //! rtmr event data
 
 use crate::sgx::QuoteError;
 
+/// The sha384 digest of 0u32, which is used in the UEFI TPM protocol
+/// as a marker. Used to advance the PCR.
+/// ```shell
+/// $ echo -n -e "\000\000\000\000" | sha384sum -b
+/// 394341b7182cd227c5c6b07ef8000cdfd86136c4292b8e576573ad7ed9ae41019f5818b4b971c9effc60e1ad9f1289f0 *-
+/// ```
+pub const UEFI_MARKER_DIGEST_BYTES: [u8; 48] = [
+    0x39, 0x43, 0x41, 0xb7, 0x18, 0x2c, 0xd2, 0x27, 0xc5, 0xc6, 0xb0, 0x7e, 0xf8, 0x00, 0x0c, 0xdf,
+    0xd8, 0x61, 0x36, 0xc4, 0x29, 0x2b, 0x8e, 0x57, 0x65, 0x73, 0xad, 0x7e, 0xd9, 0xae, 0x41, 0x01,
+    0x9f, 0x58, 0x18, 0xb4, 0xb9, 0x71, 0xc9, 0xef, 0xfc, 0x60, 0xe1, 0xad, 0x9f, 0x12, 0x89, 0xf0,
+];
+
 /// The actual rtmr event data handled in DCAP
 #[repr(C, packed)]
 pub struct TdxRtmrEvent {
@@ -88,3 +100,16 @@ impl From<TdxRtmrEvent> for Vec<u8> {
         res
     }
 }
+
+#[cfg(test)]
+mod test {
+    use super::UEFI_MARKER_DIGEST_BYTES;
+
+    #[test]
+    fn test_uefi_marker_digest() {
+        assert_eq!(
+            UEFI_MARKER_DIGEST_BYTES.to_vec(),
+            hex::decode("394341b7182cd227c5c6b07ef8000cdfd86136c4292b8e576573ad7ed9ae41019f5818b4b971c9effc60e1ad9f1289f0").unwrap()
+        );
+    }
+}