The text above the horizontal line is representing 1024 random bytes of physical origin by means of characters from the alphabet introduced on the first page.
The text below the horizontal line is derived from the text above it by cyclically left-shifting the character of each letter by the number of steps given by the difference between the number of characters in the alphabet and the index of the character.
It should be pointed out that left-shifting is not meant with respect to letter positions in a text, but with respect to character positions in the alphabet.