Brazilian digital forensics lab fights faked evidence

The question whether a photo showing you pulling off a mask after robbing a bank is real or fake may decide if you go to jail or not. For his research on digital video and image forensics, Anderson de Rezende Rocha from the Brazilian University of Campinas has been elected as one of this year's Microsoft Research Faculty Fellows.

The 30-year-old is an assistant professor at the university's Institute of Computing. His research focuses on digital evidence that law enforcement authorities in Brazil use to convict criminals.

Rocha's work takes two approaches to digital material. First, his research aims at detecting spoofing, attempts to cheat systems such as fingerprint or facial recognition. The second core area of his work is to develop tools to reveal forgery, the act of faking digital images or videos. "In Brazil we have had many cases where someone, for example, tried to damage the public image of a politician," he said.

Recently he was asked to inspect eight different digital images showing a Brazilian politician involved in child pornography. Rocha determined that these images were fake. Algorithms he and his team have developed helped him to reveal the Photoshop fraud. "When somebody puts two images together you very often find inconsistencies," he said. For instance, the shadows on a person's face do not match to the illumination of the surroundings. What sometimes is hard for the human eye to see, the lab's tools are able to detect.

Rocha is also capable of declaring footage to be real. Recently a surveillance camera at a gas station filmed a man getting out of his car and beating the clerk with a baseball bat. After being caught the suspect declared the video to be manipulated. "We were able to prove that it was not," said Rocha.

Very often he works as a consultant to the police. However, this work also raises new questions for him as a researcher. "They submit very difficult problems to us, for most of which we do not have solutions yet," Rocha said. Also, the evolving capabilities of image processing software consistently raise new challenges. "It's a cat and mouse game," the researcher said.

So far, Rocha collaborates with security authorities in Brazil only. However, he said police abroad could make use of his research results, too. An international conference in December will bring international forensics researchers to Brazil. Rocha is one of the organizers of the "IEEE International Workshop on Information Forensics and Security" that will take place in Foz do Iguaçu. He said people working with the international police organization Interpol were among those invited to the conference.

Rocha said winning the fellowship was a big motivator to him and his students. "It means my research is being recognized as having potential to help people and change the world somehow," he said.

Even though he said the recognition of his work was more important to him than the amount of money coming with the fellowship, Rocha already has some plans on how to spend the grant. He said he is now able to partially fund a newly opened research laboratory at the university dealing with digital document forensics. Four Ph.D. students, six master's students and one undergraduate student work there, Rocha said. The Digital Forensics Laboratory is associated with a major lab dealing with pattern analysis and machine learning.

Rocha said he will also use the money to provide students with the resources to go to conferences to discuss their research.

Rocha received his bachelor's degree in computer science from Federal University of Lavras in 2003. He received a master's degree (2006) and Ph.D. (2009) in computer science from the Institute of Computing, University of Campinas, Brazil.

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