xi. Data anonymization and pseudonymization

harmful content, such as extremist, terrorist, or pornographic content, in real-time at a high scale. While AI allows the identification of unknown or “first-generation” harmful content, hashing technology permits the detection of already-identified content so that when the same material is shared several times through several platforms it can be processed and removed at a faster rate. In this sense, this technology complements the functionalities of AI in this field and can be combined to allow for more efficient content moderation. PhotoDNA is an example of this technology that was initially developed to identify child sexual abuse material and is now more widely used on other illegal content.57 In December 2016, Facebook, Twitter, Google and Microsoft announced plans to tackle extremist content such as terrorist recruitment videos and violent terrorist imagery using PhotoDNA.58

Given that the AI applications presented in this report entail the processing of personal data, techniques such as anonymization and pseudonymization are key for the protection of the right to privacy. Although sharing some similarities, anonymization and pseudonymization are distinct concepts. Data anonymization consists of the transformation of personal data into anonymous data so that the individuals or groups of individuals to which the data belongs are no longer identifiable in the data. Anonymization can be achieved through different methods, including through pseudonymization. Pseudonymization consists of the removal or substitution of all direct identifiers with other unique identifiers in such a way that unique individuals are still distinguishable in a data set, but their identity cannot be traced back without access to additional information. It should be noted that anonymized data is still personal data as long as the anonymization is not irreversible, as with appropriate skills or technology the data could be linked back to individuals or groups.59

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57 See https://www.microsoft.com/en-us/photodna 58 Facebook. (Dec. 5, 2016) Partnering to Help Curb Spread of Online Terrorist Content. Accessible at https://about.fb.com/news/2016/12/ partnering-to-help-curb-spread-of-online-terrorist-content/ 59 United Nations Development Group. (2017). Data Privacy, Ethics and Protection: Guidance Note on Big Data for Achievement of the 2030 Agenda. Accessible at https://unsdg.un.org/resources/data-privacy-ethics-and-protection-guidance-note-big-data-achievement-2030agenda.