Privacy-preserving authentication of trees and graphs

Secure data sharing in third-party environments such as the cloud requires that both authenticity and confidentiality of the data be assured, especially when such structures encode sensitive information (such as in XML documents). Existing authentication schemes for trees and directed acyclic graphs (DAGs) are authenticity-preserving, but not confidentiality-preserving, and lead to leakage of sensitive information during authentication. In this paper, we propose a family of three leakage-free authentication schemes for (1) tree data structures, (2) directed acyclic graphs (DAGs), and (3) graphs (with cycles), which are also efficient. This family of schemes referred to as the “structural signatures” is based on the structure of the tree as defined by tree traversals and aggregate signatures. We also show through complexity and performance analysis that our scheme is practical in terms of the cost for authentication of data. We have also discussed two applications of the proposed scheme: (1) automatic correction and recovery from structural errors, and (2) secure publish /subscribe of XML documents.