The Narcotics Control Bureau (NCB) cloned the mobile phones of Rhea Chakraborty and others, which gave them access to the WhatsApp chats of film stars.

The cloning of Rhea's mobile phone was done by the NCB during an investigation into a Prevention of Money Laundering Act (PMLA) case.

The NCB's investigation in the drugs case linked to Sushant Singh Rajput's death case has caught up with several Bollywood A listers after their WhatsApp chats over banned drugs surfaced.

Some WhatsApp chats have surfaced in the media, reportedly between Rhea and others, and the probe agency is now focused on a group chat from 2017, allegedly between Bollywood actor Deepika Padukone and her manager Karishma Prakash.

The WhatsApp chats seem to have been retrieved from Jaya Saha, who was interrogated by the NCB. Jaya was also Sushant Singh Rajput's talent manager. Jaya, who is part of the Kwan Talent Management Agency, was also on this WhatsApp group with Deepika and Karishma.

So how are WhatsApp chats, which were considered private, coming out now?

WhatsApp says on its security settings that there is end-to-end encryption for all their messages, but the media and message back-up on Google Drive or any such Cloud services aren't protected by WhatsApp's end-to-end encryption.

End-to-end encryption means that the messages are visible only to the sender and the recipient, and not even to WhatsApp.

To access encrypted WhatsApp data, security and investigating agencies can take a user's phone and create a 'clone' of it on another device. This gives them access even to deleted messages with a 'mirror image' of a phone after which all data can be transferred to the separate device.

Thereafter, it is only a matter of retrieving data which agencies do by involving forensic experts. They retrieve all kinds of data like phone call records, messages, images, WhatsApp chats, as well as the data on the phone's Cloud service, like Google Drive or iCloud, including anything that has been deleted.

The NCB had said that Jaya was questioned about her chats with several other celebrities. The NCB is now probing whether Jaya procured narcotics and banned drugs for these celebrities.

Jaya's name emerged after a chat about drugs between her and Rhea, who is in jail in connection with the drugs case, was accessed by the Enforcement Directorate in the PMLA case mentioned earlier.

The defence can say that the phone was not used by them during the chat. Or as Rhea said that it was Sushant who asked her to send those messages from her phone.

Analysis of WhatsApp chats of Rhea with other entities reflected the angle of conspiracy, the NCB said.

Actors Deepika Padukone, Sara Ali Khan and Shraddha Kapoor are set to appear before the NCB at its Mumbai office on Saturday in connection with the drugs case. Actor Rakul Preet Singh has also been summoned to appear before the NCB on Friday.