By investigating Apple’s use of the model, called local differential privacy (LDP), the researchers found that individuals’ preferred emoji skin tone and political leanings could be inferred from the company’s data.
Companies collect behavioural data generated by users’ devices at scale to improve apps and services. These data, however, contain fine-grained records and can reveal sensitive information about individual users.
Companies such as Apple and Microsoft use LDP to collect user data without learning private information that could be traced back to individuals. However, the new paper, presented at the peer-reviewed USENIX Security Symposium, reveals how individuals’ emoji and website usage patterns collected using LDP can be used to collect information about an individual’s use of emoji skin tones and political affiliations.