Classification of personal text messages has many useful applications in surveillance, e-commerce, and mental health care, to name a few. Giving applications access to personal texts can easily lead to (un)intentional privacy violations. We propose the first privacy-preserving solution for text classification that is provably secure. Our method, which is based on Secure Multiparty Computation (SMC), encompasses both feature extraction from texts, and subsequent classification with logistic regression and tree ensembles. We prove that when using our secure text classification method, the application does not learn anything about the text, and the author of the text does not learn anything about the text classification model used by the application beyond what is given by the classification result itself. We perform end-to-end experiments with an application for detecting hate speech against women and immigrants, demonstrating excellent runtime results without loss of accuracy.

The authors present a privacy-preserving protocol for learning text classifiers on short texts using secure multiparty communication (SMC). Unlike differential privacy under the central model, a more popular framework at the moment for making it difficult to distinguish the presence or absence of individuals in training data for a model, this protocol aims to ensure that a pretrained classifier may be used on new text data without leaking that data to the classifier's owner. Though the underlying classifier is not a SOTA solution to the test classification problem, hate speech detection, it is a nontrivial classifier of text and can classify a single example in a matter of seconds, substantially improving over the performance of approaches using homomorphic encryption. The authors test their approach on a collection of 10,000 tweets with binary labels describing whether they are hate speech, demonstrating the effectiveness of this tool in aiding automatic moderation of sensitive content. I want to be open that I am not an expert on SMC, and my primary knowledge of privacy-preserving ML is through differential privacy and natural language processing.

Classification of personal text messages has many useful applications in surveillance, e-commerce, and mental health care, to name a few. Giving applications access to personal texts can easily lead to (un)intentional privacy violations. We propose the first privacy-preserving solution for text classification that is provably secure. Our method, which is based on Secure Multiparty Computation (SMC), encompasses both feature extraction from texts, and subsequent classification with logistic regression and tree ensembles. We prove that when using our secure text classification method, the application does not learn anything about the text, and the author of the text does not learn anything about the text classification model used by the application beyond what is given by the classification result itself.

Classification of personal text messages has many useful applications in surveillance, e-commerce, and mental health care, to name a few. Giving applications access to personal texts can easily lead to (un)intentional privacy violations. We propose the first privacy-preserving solution for text classification that is provably secure. Our method, which is based on Secure Multiparty Computation (SMC), encompasses both feature extraction from texts, and subsequent classification with logistic regression and tree ensembles. We prove that when using our secure text classification method, the application does not learn anything about the text, and the author of the text does not learn anything about the text classification model used by the application beyond what is given by the classification result itself.