I believe that this will mix new data into the entropy pool, but not actually increase the entropy estimate.
But isn't that what's happening all the time anyway, with the "environmental noise from device drivers and other sources" mentioned in the random(4) man page? What I was attempting to do is add another, external entropy source. Actually, I don't use this script hardly at all; it was more an attempt to make something useful while honing my shell scripting skills. I did learn xxd(1).
In other words, any process blocking on /dev/random will remain blocked until some other, accounted for, entropy is added.
I don't think the entropy pool has ever been drained completely (i.e., /dev/random blocked for reading) on my workstation. Except for the time I did that myself from a shell console. A few keystrokes, mouse movements, and network traffic bytes later (30 seconds or so), the pool had been refilled, according to /proc/sys/kernel/random/entropy_avail.
I believe you'll need to ioctl(RNDADDENTROPY) in order to fix that.
But this is supposed to be a shell script, not a C program! ;-)
I do appreciate your feedback and comments, thanks! Understand that I learn a lot reading our editors' stuff and others' comments.
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