Will Smith shocked tech fans when he made a surprise appearance at the Defcon hacker conference on Sunday.

The movie star was invited by security consultant Apollo Robbins to attend a talk he gave at the Las Vegas conference, allegedly as part of research for a future film.

Robbins, a sleight-of-hand artist known for picking the pockets of Secret Service agents during a meeting with President Jimmy Carter, gave the talk with Chris Hadnagy, the CEO of social engineering consultancy and training firm Social-Engineer, and Hadnagy’s colleague Michele Fincher.

Smith was impressed by a live demonstration of Robbins’ skill when he invited an attendee up on stage and stole his watch, wallet and mobile phone.

Smith was then shown around the conference halls, signing autographs for fans while inspecting hacking equipment. Hadnagy said the actor was interested in the ‘human side’ of hacking.

The film icon left after about 20 minutes. It is not known what film the superstar was researching nor whether Smith will be acting in it or producing it.