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URNG(4) Device Drivers Manual URNG(4)

urngUSB Random Number Generator devices

urng* at uhub?

The urng driver provides support for various true random number generator (TRNG) devices connected via USB. urng reads raw entropy from the device at a (hardware dependent) interval and stirs it into the system entropy pool with add_true_randomness(9).

The following devices are supported by this driver:

Araneus Alea I and II
Capable of delivering 100kbit/sec of hardware-generated entropy.
Altus Metrum ChaosKey 1.0
This device is capable of providing entropy at 10Mbit/s.

intro(4), usb(4), add_true_randomness(9)

The urng driver first appeared in OpenBSD 6.2.

The urng driver was written by Aaron Bieber <>,
Jasper Lievisse Adriaanse <>, and
Sean Levy <>.

September 25, 2017 OpenBSD-6.3