coy

coy    [koi] 

adjective.  1)  reluctant to give details  2)  pretending to be shy

"In an interview with ABC News on Tuesday night, Mrs. Clinton continued to be coy about her shortlist for the vice presidency."

"Apple's Siri gets coy about the upcoming WWDC event, when asked for hints about the Sunday event. Here is Siri's answer:  'There will be some cool stuff...'"

"Vice President Biden was coy with his plans for months, but Biden announced in October he would not run for President."