A coded letter written by a 17th-century Italian nun who claimed it had been dictated to her by the Devil has been deciphered by scientists using codebreaking software found on the Dark Web.

According to legend, Sister Maria Crocifissa della Concezione woke up after fainting to find several letters she had penned in an unintelligible mix of ancient scripts.

Sister Maria and the others at the convent of Palma di Montechiaro believed the letters were a scheme by Lucifer to convince her to turn away from God.

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Only one of Sister Maria’s letters composed in 1676 survived, and its text had stumped scholars and codebreakers since then.

Earlier this week, 341 years later, researchers from the Ludum Science Center in Sicily unscrambled the letter using an algorithm found on the Dark Web.

“We heard about the software, which we believe is used by the intelligence services for codebreaking,” Center director Daniele Abete told The Times of London. “We primed the software with Ancient Greek, Arabic, the Runic alphabet and Latin to de-scramble some of the letter and show that it really is devilish.”

The scientists concluded that the letters were a jumble of languages and were composed and written by Sister Maria herself; she had become a skilled linguist during her time at the convent.

The letter describes the relationship between humans, God and Satan in a rambling and inconsistent manner.

“God thinks he can free mortals,” Sister Maria’s letter says, adding that “this system works for no one.” The text also describes God, Jesus and the Holy Spirit as “dead weights.”

Abete said the contents of the letter made him believe she may have been suffering from schizophrenia.

“I personally believe that the nun had a good command of languages, which allowed her to invent the code, and may have suffered from a condition like schizophrenia, which made her imagine dialogues with the Devil,” Abete told The Times. “That has not stopped numerous interested Satanic sects contacting me since I published our findings.”