Silhouettes of mobile users are seen next to logos of social media apps Signal, Whatsapp and Telegram projected on a screen in this photo illustration created March 28, 2018. Reuters-Yonhap

After Telegram began actively cooperating with Korean police in investigating deepfake sex crimes, concerns are growing over the limitations of regulations as offenders migrate to other secure messaging apps to evade detection.

Since September, police have established a hotline with Telegram — a platform previously considered an impenetrable challenge for investigators — in response to the sharp rise in deepfake sex crimes involving the distribution of explicit content through encrypted messaging apps.

According to the police, the hotline has facilitated an average of three inquiries and responses a day, allowing for expedited cooperation in investigations.

Telegram has been responding within 24 hours to requests from Korean authorities and is reportedly complying with over 90 percent of the inquiries. Police are actively utilizing the data and documents obtained from Telegram to tackle online deepfake crimes.

As a result of the collaboration, Korean authorities recently arrested a key operator of a group chat involved in online sex crimes, including the production and distribution of abusive content targeting 234 victims. This marks the first case in which police apprehended a perpetrator based on information provided by Telegram.

In addition to this case, the Daejeon Metropolitan Police Agency's cyber investigation team arrested two teenagers late last year for creating and distributing deepfake pornography using women's face images in a Telegram group chat. Since January, authorities have been working to identify around 200 members of the group chat.

This shift toward cooperation followed the arrest of its founder, Pavel Durov, in France in August for refusing to comply with authorities' requests for information. Since then, the platform has been assisting law enforcement in criminal investigations.

However, as Telegram strengthens cooperation with law enforcement, offenders are shifting to other secure messaging apps to evade detection.

The most prominent alternative is Signal, known for its end-to-end encryption that makes it nearly impossible to access conversations through forensic analysis. Due to its high level of security, Signal is widely used by political and business figures worldwide.

Former Defense Minister Kim Yong-hyun was also known to have used the app to communicate with individuals involved in the Dec. 3 martial law declaration.

Other encrypted messaging apps, such as SimpleX Chat and Viber, are also emerging as alternatives. Police and law enforcement agencies continue to face challenges in obtaining assistance from the operators of these platforms.

Need for global treaty

Experts stress the need for stronger regulations, but acknowledge the challenges in enforcement.

Lee Yoon-ho, a professor of police administration at Korea Cyber University, emphasized that prevention remains the most effective approach.

"The government should actively require private companies to implement systems that prevent their platforms from being exploited for criminal activities," he said.

Meanwhile, Choung Wan, a law professor at Kyung Hee University, pointed out the limitations in regulating foreign apps.

"For overseas platforms, domestic law enforcement has no direct jurisdiction. The only option currently available is requesting cooperation," Choung said.

He noted that if Korea joins the United Nations' cybercrime convention, which has yet to take effect, the country could secure better cooperation mechanisms for cybercrime investigations.

"There has been ongoing discussions about international agreements on cybercrime, but so far there is only a treaty among European nations," he said.

"If the global cybercrime convention takes effect this year, it could provide a powerful legal framework, allowing authorities to request and enforce investigative measures without having to negotiate separate agreements with individual apps."