Using the Jitter RNG core, the rngd provides an entropy source that feeds into the Linux /dev/random device if its entropy runs low. It updates the /dev/random entropy estimator such that the newly provided entropy unblocks /dev/random.
The seeding of /dev/random also ensures that /dev/urandom benefits from entropy. Especially during boot time, when the entropy of Linux is low, the Jitter RNGd provides a source of sufficient entropy.
By using the SP800-90B-compliant Jitter RNG core library, the RNGd itself is now fully SP800-90B compliant.
To generate the shared library make followed by make install.
See jitterentropy --help or see the man page jitterentropy-rngd.1.
A systemd unit file is provided with jitterentropy.service which can be
copied to /etc/systemd/system and enabled with the command
systemctl enable jitterentropy.
The unit file ensures that the Jitter RNGd is started as one of the first daemons during the user space start process. This shall guarantee that any cryptographic daemons, like sshd or a web server, benefits from a seeded /dev/random and /dev/urandom device at the time they start up.
The version numbers for this library have the following schema: MAJOR.MINOR.PATCHLEVEL
Changes in the major number implies API and ABI incompatible changes, or functional changes that require consumer to be updated (as long as this number is zero, the API is not considered stable and can change without a bump of the major version).
Changes in the minor version are API compatible, but the ABI may change. Functional enhancements only are added. Thus, a consumer can be left unchanged if enhancements are not considered. The consumer only needs to be recompiled.
Patchlevel changes are API / ABI compatible. No functional changes, no enhancements are made. This release is a bug fixe release only. The consumer can be left unchanged and does not need to be recompiled.
Stephan Mueller smueller@chronox.de