An interesting thing to note is that systemd's FSS feature is based on a FSPRG [1] (forward-secure pseudorandom number generator) contributed by Lennart's broth

An interesting thing to note is that systemd's FSS feature is based on a FSPRG [1] (forward-secure pseudorandom number generator) contributed by Lennart's brother Bertram Poettering, based on the latter's research paper entitled Practical Secure Logging: Seekable Sequential Key Generators [2]. [1] http://cgit.freedesktop.org/systemd/systemd/tree/src/journal/fsprg.c http://cgit.freedesktop.org/systemd/systemd/tree/src/journal... [2] https://eprint.iacr.org/2013/397.pdf https://eprint.iacr.org/2013/397.pdf