Focus on Kryptos and discuss the Encrypted messages.
The ciphertext on the left-hand side of the sculpture (as seen from the courtyard) of the main sculpture contains 869 characters in total: 865 letters and 4 question marks (spacing is important).
In April 2006, however, Sanborn released information stating that a letter was omitted from this side of Kryptos "for aesthetic reasons, to keep the sculpture visually balanced".There are also three misspelled words in the plaintext of the deciphered first three passages, which Sanborn has said was intentional, and three letters (YAR) near the beginning of the bottom half of the left side are the only characters on the sculpture in superscript.
The right-hand side of the sculpture comprises a keyed Vigenère encryption tableau, consisting of 867 letters.
One of the lines of the Vigenère tableau has an extra character (L). Bauer, Link, and Molle suggest that this may be a reference to the Hill cipher as an encryption method for the fourth passage of the sculpture.  However, Sanborn omitted the extra letter from small Kryptos models that he sold.Sanborn worked with a retiring CIA employee named Ed Scheidt, Chairman of the CIA Office of Communications, to come up with the cryptographic systems used on the sculpture.Sanborn has revealed that the sculpture contains a riddle within a riddle, which will be solvable only after the four encrypted passages have been deciphered.He has given conflicting information about the sculpture's answer, saying at one time that he gave the complete solution to the then-CIA director William Webster during the dedication ceremony; but later, he also said that he had not given Webster the entire solution. He did, however, confirm that a passage of the plaintext of the second message reads "Who knows the exact location? Only WW."
Sanborn also confirmed that should he die before the entire sculpture becomes deciphered, there will be someone able to confirm the solution. In 2020, Sanborn stated that he planned to put the secret to the solution up for auction once he dies.
encrypted Vigenère Ed Scheidt William Webster superscript sculpture Hill cipher