A 900-year-old rune code used by Vikings may have been solved thanks to a scholar from the University of Oslo.

The message, which was found among 80 Norse inscriptions says, “kiss me.” The tone may be a playful one suggesting that the ancient people sent each other short messages. K. Jonas Nordby, the scholar responsible for deciphering the message, says the ancient jötunvillur code dates back to the 12th or 13th century. It was found on nine inscriptions discovered in different parts of Scandinavia, the Guardian reports.

“It’s like solving a puzzle,” Nordby told the Norwegian website forskning.no. “Gradually I began to see a pattern in what was apparently meaningless combinations of runes.”

The findings, published in the Futhark: International Journal of Runic Studies, describes how Nordby was able to decipher the code while studying a 13th century stick where two men named Sigurd and Lavrans had carved their names in both code and in standard runes.

"The thing that solved it for me was seeing these two old Norse names, Sigurd and Lavrans, and after each of them was this combination of runes which made no sense," Nordby told the Guardian, explaining that in jötunvillur code the original runic character is replaced with the last sound of the rune name.

"I thought 'wow, this is the system, this is the solution, now we can read this text," Nordby said adding the code was complex, especially since many runes end with the same sound. Nordy believes the rune codes were not used to exchange secret information but to teach others how to crack codes and send short messages.

“People challenged one another with codes. It was a kind of competition in the art of rune making. This testifies to a playfulness with writing that we don’t see today,” Nordby told ScienceNordic.

The runes were written on sticks that were considered “everyday objects,” Nordby said. "They were used to communicate, like the SMSes of the Middle Ages – they were for frequent messages which had validity in the here and now," he said. "Maybe a message to a wife, or a transaction."

While nine out of the 80 runic writings Nordby studied were written in jötunvillur code, others could be deciphered using a Caesar cipher, an encryption technique that involves replacing each letter of a secret message with a different letter of the alphabet. Nordby is the first to decipher the mysterious jötunvillur code, which puzzled experts for years.

Henrik Williams, a professor at Uppsala University’s Department of Scandinavian Languages and a Swedish expert on runes, lauds Nordby’s discovery.

“Above all, it helps us understand that there were more codes than we were aware of. Each runic inscription we interpret raises our hopes of soon being able to read more. This is pure detective work and each new method improves our chances,” Williams said.