(I work at Tillitis) Yes, OpenTitan is cool. The philosophical discussion about FPGAs and ASICs in the context of security is interesting. For the TKey FPGA

(I work at Tillitis) Yes, OpenTitan is cool. The philosophical discussion about FPGAs and ASICs in the context of security is interesting. For the TKey FPGA design you can inspect both the design (https://github.com/tillitis/tillitis-key1/tree/main/hw/application_fpga https://github.com/tillitis/tillitis-key1/tree/main/hw/appli...) and the toolchain (Icestorm: https://github.com/tillitis/tillitis-key1/blob/main/doc/toolchain_setup.md#gateware-yosysicestorm-toolchain https://github.com/tillitis/tillitis-key1/blob/main/doc/tool... that contains synthesis, place&route, NVCM programming tools). However, the internal FPGA fabric—consisting of the logic cells, memory, and interconnects—remains proprietary. Most Open Source ASICs I am aware of provide open-source RTL designs, but the tool chains are usually proprietary. Hard macros, memories, security mechanisms, etc are typically also closed source. And then there is the manufacturing process itself that is not transparent. There isn’t a definitive answer as to what constitutes “enough” openness for security inspections. Individuals have different thresholds for what they consider acceptable. So far we chose as much open source as possible.