05. Deepfakes

Deepfakes:

• AI to transplant faces onto other person’s face
• Also can fake:
  • Voice
  • Gait
    • Humans very sensitive to gait; character animation is difficult which is why motion capture is usually used
• 2017: r/deepfakes, mostly for porn
  • Existed previously in research institutions since the 90s

Theory:

• Deep learning used to train generative neural networks such as:
  • Autoencoders
  • Generative adversarial networks (GANs)

Autoencoders:

• Reduce image to lower-dimensional latent space
  • Contains key features about facial features and body pose
• Decoder: reconstructs image from latent representation
• Train model for a specific target
  • Match keypoints to superimpose the target’s facial features

Generative adversal networks (GANs):

• GAN trains generator (decoder) and discriminator
• Generate creates new images; discriminator attempts to determine if the image is generated or not
• Makes them realistic and difficult to spot deepfakes
  • Researchers have made algorithms to detect this
    • Shadow/lighting inconsistencies
    • Light reflections in eyes
    • Wael AbdAlmageed:
      • 1st gen: Spatio-temporal inconsistencies (using RNNs)
      • 2nd gen: end-to-end deep networks to detect frequency information
        • One branch amplifies low frequency information with the Laplacian of Gaussian
        • The second branch propagates color information
    • DARPA competitions
  • But these can then be used to update the discriminator

Use-cases:

• Movies: dead actors/de-aging
• Identity fraud
  • Online/app video-based identification (liveness tests)
• Porn
• Blackmail
  • Revenge porn
  • Related: if there is real comprimising footage of a victim, they can just claim that it is a deepfake
• Fake news
  • Declaring war as political leaders
• Sockpuppets
  • Users active online and in traditional media that don’t exist
  • Video footage of people considered to be trustworthy
  • Example: ‘Oliver Taylor’ persona

Exploitation, intimidation, personal sabotage

Prevention:

• Digital signing of images/videos from cameras and smartphones
  • But can also be used to track down dissidents