The first thing The Great Cipher used by Louis XIV did well was not being a monoalphabetic cipher. These ciphers are too susceptible to frequency analysis, making them crackable in a matter of hours at the most. Instead, the Great Cipher is more along the lines of a polyalphabetic cipher. Instead of letters, however, the cipher alphabets are compromised of numbers. But the thing that really makes this cipher a strong one is the fact that these numbers represent single syllables, letters, or even commands instead of just single letters. In doing this, deciphering The Great Cipher would take years.
This cipher took 200 years to decipher due to the odd nature of the cipher. No conventional ciphers substituted numbers for both syllables and letters, as well as having some traps lain within. Due to this, nobody knew how to begin deciphering it. It was only through the efforts of Bazeries that this cipher was eventually cracked. Even so, it took Bazeries 3 whole years to figure out the messages hidden behind the code. He was only able to crack the code as a result of his very out of the box thinking and pure determination. After trying polyalphabetic combinations, which are hard enough to crack on their own due to the pure number of possibilities that exist, and diagraphs, which also took a long time, Bazeries thought to try syllables. It was only after trying many different combinations that he found a single phrase which worked. He then used this word to painstakingly decipher the rest of the text. The pure creativeness of The Great Cipher led to its strength, and the only way it could be decoded was through equal creativity.