The panel would have been a first for Apple, but the company pulled out of the discussion at the last minute, Black Hat Director Jeff Moss said in an interview Friday.
"Marketing got wind of it, and nobody at Apple is ever allowed to speak publicly about anything without marketing approval," he said.
The panel would have been a highlight of the show, giving attendees an insider look at Apple's security response team. Apple is notoriously secretive about its security policies, a stance that has made it a constant target of criticism in the security community.
"It was them talking about security engineering and how they take security seriously," Moss said. "It would have put Apple in a positive light."
The talk was accepted by Black Hat organizers on July 3 and abruptly cancelled on July 21, he said.
"Due to circumstances beyond my control, I regret that I will not be able to participate in Black Hat this year," the panel's organizer said in an e-mail to conference officials, read over the telephone by Moss Friday.
Moss declined to say who from Apple was scheduled to speak on the panel, saying that by naming them, he could put their jobs in jeopardy.
Engineers thought that the panel would be approved by marketing because they were not set to answer any questions from the audience, he said.
This was not the first Apple talk to be pulled from Black Hat in recent weeks. Another talk, proposed by consultant Charles Edge on Apple's FileVault encryption software, was also pulled recently, Moss said.
That talk had not actually been accepted by conference organizers, but it was the proposal to do the talk that was withdrawn, Moss said.
Edge, a consultant with 318 Inc. in Santa Monica, California, declined to comment, but according to a source familiar with the matter, the talk was pulled because Edge has signed confidentiality agreements with Apple.
An Apple spokesman was unable to comment immediately for this story.
Moss said that Apple was welcome back at the show, should the company change its mind.