One must first accept the WORD of the "unknown author" on the existence of the iron box, ciphers, and the "letters" which form the foundation of the Beal adventure/treasure story.
This "unknown author" injected himself into the Beale story with his interview with Morriss during the 2nd year of the Confederate War, and then with his attempts of solving the ciphers, DOI C2 being presented as "solved", the other two balked all his efforts. So in an altruistic moment, he contacts Ward to act as copyright agent and publisher, so others can give the unsolved ciphers a go, and lead them to fabulous treasure.
The ONLY existence of these letters and ciphers is based on the words of this "unknown author", nowhere else, and the same can be said concerning the Beale adventure that is only documented in these letters.
Codebreakers from WWI, WWII, and the NSA with their supercomputers that go through millions of information daily as America's first line of defense, all conclude that C1 & C3 do not contain an actual valid message., just random numbers posing as a real cipher.
These conclusions were made by professionals in the field of cryptology intelligence, who deal with codes and ciphers on a daily basis, that have served our country in war, cold war, and peace, and yes, to dismiss these conclusions is just an omission of hubris on those who do question there conclusions.