Many algorithms can be devised to generate random numbers from an internet radio digital stream. But these will be "pseudo-random" numbers. You can improve their quality if you use the "splitting" of digital streams. Splitting can be linear (periodic) and non-linear. Periodic splitting - when you divide the original stream of numbers, for example, into 10 streams, sending every tenth number to your own stream. Nonlinear splitting - when numbers are selected from the source stream according to some given algorithm. Something like: first, fifth, seventh, nineteenth, etc. And already in the new streams, the given sequence of bytes is taken and a random number is selected and the cipherbook page is formed.