Abstract: In an example embodiment, a protocol for private set intersection is introduced that provides for two-party computation. Each party has a private data set and both parties want to securely compute the intersection of their sets, such that only the result is revealed and nothing else. Construction rules are provided that rely on the evaluation of a branching program (BP) using a fully homomorphic encryption (FHE) scheme. Using the properties of an FHR scheme, a non-interactive protocol is built with extendable functionalities. Thus, not only can the intersection be securely computed but the result can be used for further secure computations. Furthermore, the communication overhead for practical applications is independent of the server's set size, allowing for easy scalability.

Abstract: A non-interactive protocol is provided for evaluating machine learning models such as decision trees. A client can delegate the evaluation of a machine learning model such as a decision tree to a server by sending an encrypted input and receiving only the encryption of the result. The inputs can be encoded as vector of integers using their binary representation. The server can then evaluate the machine learning model using a homomorphic arithmetic circuit. The homomorphic arithmetic circuit provides an implementation that requires fewer multiplication than a Boolean comparison circuit. Efficient data representations are then combined with different algorithmic optimizations to keep the computational overhead and the communication cost low. Related apparatus, systems, techniques and articles are also described.

Abstract: Systems, methods, and computer-readable media are disclosed for secure integer comparison using binary trees. A server may receive a first encrypted input and a public encryption key from a client. The server may create a binary tree representing a second encrypted input. The server may evaluate the first encrypted input on the binary tree. The evaluation may comprise computing decision bits along a plurality of paths of the binary tree. The decision bits may then be aggregated along each path of the binary tree and the aggregation stored at a leaf node of each path. The leaf node of each path may be evaluated to obtain a comparison result. The comparison result may be encrypted with the public encryption key. The server may send the comparison result to the client for decryption. The comparison result may indicate whether the first input was larger than the second input.