PhotoDNA is a technology developed by Microsoft and improved by Hany Farid of Dartmouth College that computes hash values of images, video and audio files to identify similar images.PhotoDNA is primarily used in the prevention of child pornography, and works by computing a unique hash that represents the image. This hash is computed such that it is resistant to alterations in the image, including resizing and minor color alterations. It works by converting the image to black and white, resizing it, breaking it into a grid, and looking at intensity gradients or edges.
The Central Bureau of Investigation in India is now publishing regulations requiring all social networking sites and users to use PhotoDNA technology to compare images to combat child abuse.
Simply put, the PhotoDNA system scans the user’s picture each time, then finds out what may be child abuse and locks the suspect. The use of PhotoDNA to combat local child sexual abuse is also child protection.
However, this decision has caused many Indian Internet users to resent. These users think that PhotoDNA scanning images have obviously violated the privacy of users. The Internet Freedom Foundation said that if PhotoDNA is used to investigate common crimes, it has seriously violated the original purpose of the engineers to develop the technology.
PhotoDNA should only be used to check cases related to child sexual abuse, and any use other than this will infringe the user’s privacy. Companies such as Twitter, Microsoft, YouTube and Facebook do not allow the use of this software, even exclusively for blocking extremist content or terrorist messaging.