Finnbarr P. Murphy has a new UEFI tool that checks your firmware for RNGs, and it sounds like he’s found some Lenovo Thinkpad errors with it:
[…] Here is a small UEFI shell utility that checks your firmware for available RNGs: […] I built the utility on a 64-bit Fedora 24 platform using GCC and UDK2015. I have not tried building a 32-bit utility nor have I build it using Visual Studio or other development frameworks – so do not be surprised if you have modify either the code or the build recipe in these cases. I tested the utility on a Lenovo T450 using firmware version JBET60WW (1.24) and was surprised to find that the firmware did not appear to support any RNGs as evidenced by the zero RNG algorithm count returned. However, by explicitly, testing for the default RNG if the count was zero, it was possible to determine that the T450 did in fact at least support the default RNG. Perhaps, I am not parsing the UEFI specification correctly but I would expect the RNG count returned by GetInfo to include the default RNG. Interestingly, when I build and load the UDK2015 test RNG DXE driver which contains a reference counter mode DRBG (Deterministic Random Bit Generator) conforming to NIST SP 800-90a, the algorithm count returned by GetInfo jumps to 2. This leads me to suspect that their is a bug in the firmware w.r.t. to the RNG protocol implementation. Please let me know if I am incorrect in my assumptions or observations.