Add release notes for Bellatrix

Co-authored-by: Michael Cardell Widerkrantz <mc@tillitis.se>

Signed-off-by: Joachim Strömbergson <joachim@assured.se>, Michael Cardell Widerkrantz <mc@tillitis.se>

doc/release_notes.md

@@ -3,11 +3,90 @@
 Descriptions of the tagged TKey releases.
 
 
-## Tag XYZ
+## TK1-23.03
+This is the official release of the "Bellatrix" version of
+the Tillitis TKey device. This version is ready for general
+use.
+
+Given the Docker config, and the generic UDS.hex and UDI.hex,
+a clean build should generate the following digest:
+```
+shasum -a256 application_fpga.bin
+f11d6b0f57c5405598206dcfea284008413391a2c51f124a2e2ae8600cb78f0b  application_fpga.bin
+```
+
+
+### New and improved functionality
+
+- (ALL) The TKey HW design, FW, protocol and first applications has
+  been audited by a third party. No major issues was found, but the
+  audit have lead to several updates, changes and fixes to improve
+  the security and robustness. The third party report will be
+  published when completed.
+
+- (APPS) Applications can now use the whole 128 kByte RAM.
+
+- (FW) The firmware now use the `FW_RAM` for the stack. It keeps no
+  .bss or .data segments and only uses RAM for loading the
+  application.
+
+- (FW) The firmware has been hardened and the state machine simplified
+  to reduce the number of commands that can be used and in which
+  order.
+
+- (FW) Steady white LED while waiting for initial commands. LED off
+  while loading app.
+
+- (HW) The memory system now has an execution monitor. The monitor
+  detects attempts at reading instructions from the firmware ram.
+  The execution monitor can alwo, when enabled by an application,
+  detect attempts at reading instructions from the application
+  stack. If any such attempt is detected, the memory system will
+  force the CPU to read an illegal instruction, triggering the
+  trap state in the CPU.
+
+  Note that the execution monitor can only be enabled, not
+  disabled. The address range registers defining the region
+  protected by the monitor can only be set when the monitor
+  has not yet been enabled.
+
+- (HW) The CPU trap signal is now connected to an illegal instruction
+  trap indicator. When an illegal instruction is detected, the RGB LED
+  will start flashing red. Note that the CPU will stay in the trap
+  state until the TKey device is disconnected.
+
+- (HW) The RAM memory now includes an initial adress and scrambling
+  mechanism to make it harder to find assets generated by and
+  stored in the RAM by applications. The address space layout
+  randomizarion (ASLR) and data value scrambling is set up by the
+  firmware before the application is loaded, and does not affect
+  how applications executes.
+
+- (HW) The UART Rx FIFO now allows applications to read out the
+  number of bytes received and not yet consumed by the application.
+
+- (HW) The FPGA bitstream can now be stored in the non volatile
+  configuration memory (NVCM). This is done using of a new icestorm
+  tool developed partly in the projecy and sponsored by Tillitis
+  and Mullvad. The tool supports locking down NVCM access after
+  writing the FPGA bitstream to the memory.
+
+- (TOOLS) There is now a Docker config setting up all tools as needed
+
+- (TOOLS) There is now a version of iceprog able to write to the FPGA
+  bitstream to the NVCM and lock the NVCM from external access
+
+
+### Bugs fixed
+- No known bugs have been fixed. Numerous issues has been closed.
+
+
+### Limitations
+
+- The RAM address and data scrambling in this release is not
+  cryptographically secure. It his however randomized every time
+  a TKey device is powered up.
 
-XYZ is a general release of the development kit first presented
-as a limited engineering-release. The main changes are polishing,
-completion and bug fixing since the engineering-releases.
 
 ## engineering-release-2