Only half of social networking users trust their online friends to keep their data secure, according to a survey released Tuesday by ID Analytics, a consumer risk management provider. The survey of more than 1,000 adults in the United States, of whom 387 have joined social networking sites, also found that some users are willing to accept the friend request of a complete stranger. Five percent of respondents said they would accept all friend requests regardless of who sent them, and men are twice more likely than women to accept invites from anyone of the opposite sex.