Deepfake CAPTCHA: A Method for Preventing Fake Calls

Lior Yasur, Guy Frankovits, Fred M. Grabovski, Yisroel Mirsky

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Deep learning technology has made it possible to generate realistic content of specific individuals. These 'deepfakes' can now be generated in real-time which enables attackers to impersonate people over audio and video calls. Moreover, some methods only need a few images or seconds of audio to steal an identity. Existing defenses perform passive analysis to detect fake content. However, with the rapid progress of deepfake quality, this may be a losing game. In this paper, we propose D-CAPTCHA: an active defense against real-time deepfakes. The approach is to force the adversary into the spotlight by challenging the deepfake model to generate content which exceeds its capabilities. By doing so, passive detection becomes easier since the content will be distorted. In contrast to existing CAPTCHAs, we challenge the AI's ability to create content as opposed to its ability to classify content. In this work we focus on real-time audio deepfakes and present preliminary results on video. In our evaluation we found that D-CAPTCHA outperforms state-of-the-art audio deepfake detectors with an accuracy of 91-100% depending on the challenge (compared to 71% without challenges). We also performed a study on 41 volunteers to understand how threatening current real-time deepfake attacks are. We found that the majority of the volunteers could not tell the difference between real and fake audio.

Original languageAmerican English
Title of host publicationASIA CCS 2023 - Proceedings of the 2023 ACM Asia Conference on Computer and Communications Security
Number of pages15
ISBN (Electronic)9798400700989
StatePublished - 10 Jul 2023
Event18th ACM ASIA Conference on Computer and Communications Security, ASIA CCS 2023 - Melbourne, Australia
Duration: 10 Jul 202314 Jul 2023

Publication series

NameProceedings of the ACM Conference on Computer and Communications Security


Conference18th ACM ASIA Conference on Computer and Communications Security, ASIA CCS 2023


  • deep fake
  • deep learning
  • Deepfake
  • fake calls
  • impersonation
  • security
  • social engineering
  • voice cloning

All Science Journal Classification (ASJC) codes

  • Software
  • Computer Networks and Communications


Dive into the research topics of 'Deepfake CAPTCHA: A Method for Preventing Fake Calls'. Together they form a unique fingerprint.

Cite this