Jessica Brown Findlay felt a "colossal amount of shame" after private photos were hacked from her phone.
The former 'Downton Abbey' star was one of a number of high-profile women targeted in 2014 and she admits she didn't speak out about the scandal at the time because she didn't know who to turn to.
She said: "I was so quiet about everything, because I felt such a colossal amount of shame and I had no idea if I could even say it out loud.
"I didn't know where I could go or who I could properly talk to.
"Eventually I realised I wanted to look at this properly, find other people who have gone through similar things and talk about it openly."
The 27-year-old beauty can next be seen on TV playing a prostitute in Georgian times in 'Harlots' and has called for more protection and better rights for sex workers.
Asked if there needs to be change to a system that punishes prostitutes but not their clients, she told Marie Claire magazine: "I think it's less about punishing punters and more about protecting and giving rights to the people who are providing a service.
"In the same way, making abortion illegal isn't going to put a stop to it - it's just going to make it unsafe.
"One of the really shocking things I've found with doing the show is discovering we haven't come as far as we think."
But Jessica is astonished it has taken so long to bring the subject to public attention.
She said: "If I did [have any reservations], they were immediately extinguished when I had a meeting with Moira Buffini (producer) and Coky Giedroyc (director).
"The more I explored the world around the subject matter, the more I thought, 'F***ing hell, how has it taken to 2017 to have this frank conversation about the world's oldest profession.'"