A while ago a posted a dmesg for a TRNG USB device (the MoonBase Otago OneRNG) per <http://openbsd-archive.7691.n7.nabble.com/dmesg-OneRNG-hardware-RNG-plugged-into-Soekris-5501-td276480.html>.
I'm looking at adding support for this device but haven't splunked too much into the OpenBSD kernel before, and I'm looking for advice. The OneRNG was manufactured to present itself as a modem and in the Linux sample source code the (user space) process to first initialize the device by echoing some commands to the device and then cat its output to rngd. For the OpenBSD side, I found /usr/src/sys/dev/usb/ualea.c which is another USB-based TRNG. The model there would be to usbd_transfer(9) from the device and then forward it via add_true_randomness(9). However, because the OneRNG was manufactured to look like a modem, the other possibility is to have it recognised in /usr/src/sys/dev/usb/umodem.c. If that's the case, though, it's unclear to me what the mechanism should be to pull the data from the OneRNG and give it to the kernel; presumably we don't want any userspace code here. Am I correct in assuming that the ualea mechanism is probabably the right way to go? Devin
