What activities increases the entropy significantly. Please describe your observation in your repo
Task 3: Measure the Entropy of Kernel In the virtual world, it is difficult to create randomness, i.e., software alone is hard to create random numbers. Most systems resort to the physical world to gain the randomness. Linux gains the randomness from the following physical resources: void add_keyboard_randomness(unsigned char scancode); void add_mouse_randomness(__u32 mouse_data); void add_interrupt_randomness(int irq); void add_blkdev_randomness(int major); The first two are quite straightforward to understand: the first one uses the timing between key presses; the second one uses mouse movement and interrupt timing; the third one gathers random numbers using the interrupt timing. Of course, not all interrupts are good sources of randomness. For example, the timer interrupt is not a good choice, because it is predictable. However, disk interrupts are a better measure. The last one measures the finishing time of block device requests. The randomness is measured using entropy, which is different from the meaning of entropy in the information theory.
Here, it simply means how many bits of random numbers the system currently has. You can find out how much entropy the kernel has at the current moment using the following command. $ cat /proc/sys/kernel/random/entropy_avail Let us monitor the change of the entropy by running the above command via watch, which executes a program periodically, showing the output in fullscreen. The following command runs the cat program every 0.1 second. $ watch -n .1 cat /proc/sys/kernel/random/entropy_avail Please run the above command. While it is running, move your mouse, click your mouse, type somethings, read a large file, visit a website. What activities increases the entropy significantly. Please describe your observation in your report
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