Having a secret language is the kind of thing that you do with your friends did when you're eight-years-old.
It's not the sort of thing you'd expect heads of state to be doing, but with the number of leaks and secrets that are revealed these days, it might be a smart security measure for some to adopt.
One major figure who thought of this unique form of communication centuries before anyone else was the former Spanish monarch, King Ferdinand II of Aragon.
During the Naples war in the early 1500s, Ferdinand engaged in a series of cryptic letters with one of his army commanders Gonzalo Fernández de Cordoba.
The letters were written in a code that contained more than 200 symbols, which looked more like an alien language than anything else previously seen by experts.
After all that time, the Spanish intelligence agency El Centro Nacional de Inteligencia has finally been able to unravel the code.
The letters, which were 20 pages long, took six months to understand and contained military instructions and tactics for the commander to carry out.
A spokesperson from the Museum of the Army of Toledo, where the letters are on loan, is quoted as saying in a press conference, via RTVE:
In the historical situation of that time, in the Naples war, which affected mainly France and Spain, but also the Germanic Empire, the Papal States, the Ottoman Empire and the Italian State Cities, it was essential to keep the secrecy in the negotiations in military strategies and even in betrayals, and any neglect at one point could disrupt strategies.
These two letters, now analysed, allow experts to fully understand the military instructions and tactics discussed by the King Ferdinand II and his commander.
We also understand better the kind of threats they were fearing.
In their research, they discovered that the letters actually contained 88 different symbols, while 237 letters were combined to form hybrid letters.
They noticed repeated symbols in the two letters, but sometimes those symbols were changed, and even red herrings were found in some areas.
The letters also lacked any punctuation or spaces, making them even more difficult to comprehend.
According to ABC, experts have now managed to determine that this method was something called "Vigenere" where the alphabetical text is interwoven.
The letters didn't just contain military instructions, they also detailed the Catholic king's insecurities, his disagreements with the commander and even the topic of Spanish officers marrying Italian widows.
The spokesperson added:
In these letters, we understood the king was feeling threatened for the future of his kingdom.
The King of Aragon was a perpetual conqueror and was also sponsoring Christopher Columbus and his path of the New World.
Now that the letters have been cracked by the intelligence agency and the method disclosed, experts hope that they can begin to understand other letters sent by the king to his commander from the same period.