Puzzle solved!
The composite cofactor of the RSA public key factored into 91-digit and 97-digit prime numbers. With these factors, we are able to decrypt the RSA-encrypted literary quote. What quote did Donald Knuth hide so well? His remarks (as reported) were as follows:-- "O Rowty-owty tiddly-owty Tiddly-owty tiddly-owty Highty-ighty tiddly-ighty Tiddly-ighty ow." --G. K. Chesterton (1905) This is from The Tremendous Adventures of Major Brown, the first in the collection of short stories The Club of Queer Trades.

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