Document status of MPS upstreaming
Signed-off-by: Hanno Becker <hanno.becker@arm.com>
diff --git a/docs/architecture/tls13-experimental.md b/docs/architecture/tls13-experimental.md
index 3db16e0..10cbfa1 100644
--- a/docs/architecture/tls13-experimental.md
+++ b/docs/architecture/tls13-experimental.md
@@ -47,3 +47,22 @@
Those functions are implemented in `library/ssl_tls13_keys.c` and
tested in `test_suite_ssl` using test vectors from RFC 8448 and
https://tls13.ulfheim.net/.
+
+- New TLS Message Processing Stack (MPS)
+
+ The TLS 1.3 prototype is developed alongside a rewrite of the TLS messaging layer,
+ encompassing low-level details such as record parsing, handshake reassembly, and
+ DTLS retransmission state machine.
+
+ MPS has the following components:
+ - Layer 1 (Datagram handling)
+ - Layer 2 (Record handling)
+ - Layer 3 (Message handling)
+ - Layer 4 (Retransmission State Machine)
+ - Reader (Abstracted pointer arithmetic and reassembly logic for incoming data)
+ - Writer (Abstracted pointer arithmetic and fragmentation logic for outgoing data)
+
+ Of those components, the following have been upstreamed
+ as part of `MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL`:
+
+ - Reader ([`library/mps_reader.h`](../../library/mps_reader.h))