NATICK, Mass. — A little-known war museum outside Boston is drawing back the curtain on a key secret of “The Imitation Game,” giving visitors a rare chance to use the complex Nazi Enigma coding machines at the center of the Oscar-nominated film.

The Museum of World War II’s new exhibit “The Most Secret Top Secret: The German Enigma Code Machines” is billed as the largest public display of the encryption machines, which the Nazis used to encrypt most of their military communications.

Among the nine machines in the exhibit are two that visitors can use to encrypt and decrypt their own messages.

Museum founder and historian Kenneth Rendell says only the National Security Agency has more Enigma coding machines. The NSA owns more than 50 and loans them out to museums around the country.

“But this is the only collection where you actually can touch the machines and you can operate them,” he said Thursday from his museum in Natick, 20 miles outside Boston. It’s regarded as one of the more comprehensive collections of World War II artifacts in the U.S.

FILM GETS MOST OF IT RIGHT

Rendell says “The Imitation Game,” which stars Benedict Cumberbatch and Keira Knightley, may fudge some facts and amp up the drama, but it still gets a lot right about the Allied effort to crack the Germans’ sophisticated communications code during World War II.

He says the movie’s biggest achievements are introducing the critical wartime contributions of pioneering British mathematician and computer scientist Alan Turing to new audiences and showcasing the legendary complexity of the Nazi code machines.

“It’s too bad that many of the folks depicted in the movie did not live long enough to see their story told,” Rendell said.

He says the movie shows the importance of the “intellectual side” of warfare: how technologies like computers, radar, jet engines and plastics were developed during the war years.

Turing, who died in 1954 of cyanide poisoning, is widely considered a founding father of computer science. His work led to the development of concepts like artificial intelligence.

But Rendell acknowledges the movie makes some missteps.

“All of this drama about him being blackmailed during the war because he was gay, it wasn’t true. In those circles, I just don’t think anyone cared,” Rendell said. “And there were a lot of women breaking codes at Bletchley Park, not just one.”

Critics have noted other liberties in the movie, which is up for best picture and seven other Academy Awards Sunday night.

For example, the name of Turing’s code-breaking machine in the film is Christopher, apparently after a childhood crush. It was actually called Victory.

Rendell suggests Turing’s mathematical genius was also helped by human error.

The Nazis were either too confident no one would crack their code, he says, or they simply became careless over time. “Human nature was really a big element,” he says. “Because it was supposed to be unbreakable, people relaxed.”