random(4): Fortuna: allow increased concurrency Add experimental feature to increase concurrency in Fortuna. As this diverges slightly from canonical F

random(4): Fortuna: allow increased concurrency Add experimental feature to increase concurrency in Fortuna. As this diverges slightly from canonical Fortuna, and due to the security sensitivity of random(4), it is off by default. To enable it, set the tunable kern.random.fortuna.concurrent_read="1". The rest of this commit message describes the behavior when enabled. […] * https://github.com/freebsd/freebsd-src/commit/179f62805cf05c3ae334c03dd94cb4c2da46c716 https://github.com/freebsd/freebsd-src/commit/179f62805cf05c... random(4): Flip default Fortuna generator over to Chacha20 The implementation was landed in r344913 and has had some bake time (at least on my personal systems). There is some discussion of the motivation for defaulting to this cipher as a PRF in the commit log for r344913. As documented in that commit, administrators can retain the prior (AES-ICM) mode of operation by setting the 'kern.random.use_chacha20_cipher' tunable to 0 in loader.conf(5). Approved by: csprng(delphij, markm) Differential Revision: https://reviews.freebsd.org/D22878 * https://github.com/freebsd/freebsd-src/commit/68b97d40fbe826585813f05042209db5490dbe08 https://github.com/freebsd/freebsd-src/commit/68b97d40fbe826...