text: This paper proposes a client-server decision tree learning method for outsourced private data. The privacy model is anatomization fragmentation: the server sees data values, but the link between sensitive and identifying information is encrypted with a key known only to clients. Clients have limited processing and storage capability. Both sensitive and identifying information thus are stored on the server. The approach presented also retains most processing at the server, and client-side processing is amortized over predictions made by the clients. Experiments on various datasets show that the method produces decision trees approaching the accuracy of a non-private decision tree, while substantially reducing the client's computing resource requirements.
  @cite_1: We present an algorithm designed to efficiently construct a decision tree over heterogeneously distributed data without centralizing. We compare our algorithm against a standard centralized decision tree implementation in terms of accuracy as well as the communication complexity. Our experimental results show that by using only 20 of the communication cost necessary to centralize the data we can achieve trees with accuracy at least 80 of the trees produced by the centralized version.
  @cite_12: Privacy and security concerns can prevent sharing of data, derailing data-mining projects. Distributed knowledge discovery, if done correctly, can alleviate this problem. We introduce a generalized privacy-preserving variant of the ID3 algorithm for vertically partitioned data distributed over two or more parties. Along with a proof of security, we discuss what would be necessary to make the protocols completely secure. We also provide experimental results, giving a first demonstration of the practical complexity of secure multiparty computation-based data mining.
summary: Another approach related to mining anatomized data in the client-server database model is vertically partitioned data mining (e.g., @cite_1 @cite_12 ). Vertically partitioned data mining makes strong assumptions about data partitions and what data can be shared, and typically assume that each party holding data has significant computational power. For example, some decision tree techniques assume that two tuples of two partitions can be linked directly to each other, that the tuples are ordered in the same way; and that the class labels are known for both partitions. In one sense, our problem is easier, as one party (client) can see all the data. However, we assume this party (again client) does not have the resources to even store all the data, much less to build the tree.