XML is increasingly becoming the format of choice for information exchange on the Internet. As this trend grows, one can expect that documents (or collections thereof) may get quite large, and clients may wish to query for specific segments of these documents. In critical areas such as healthcare, law and finance, integrity is essential. In such applications, clients must be assured that they are getting complete and correct answers to their queries. Existing methods for signing XML documents cannot be used to establish that an answer to a query is complete. A simple approach has a server processing queries and certifying answers by digitally signing them with an on-line private key; however, the server, and its on-line private key, would be vulnerable to external hacking and insider attacks. We propose a new approach to signing XML documents which allows untrusted servers to answer certain types of path queries and selection queries over XML documents without the need for trusted on-line signing keys. This approach enhances both the security and scalability of publishing information in XML format over the Internet. In addition, it provides greater flexibility in authenticating parts of XML documents, in response to commercial or security policy considerations.

XML is increasingly becoming the format of choice for information exchange, in critical areas such as government, finance, healthcare and law, where integrity is of the essence. As this trend grows, one can expect that documents (or collections thereof) may get quite large, and clients may wish to query for specific segments of these documents. In critical applications, clients must be assured that they are getting complete and correct answers to their queries. Existing methods for signing XML documents cannot be used to establish that an answer to a query is complete. A simple approach has a server processing queries and certifying answers by digitally signing them with an on-line private key; however, the server, and its on-line private key, would be vulnerable to external hacking and insider attacks. We propose a new approach to signing XML documents which allows untrusted servers to answer certain types of path queries and selection queries over XML documents without the need for trusted on-line signing keys. This approach enhances both the security and scalability of publishing information in XML format over the internet. In addition, it provides greater flexibility in authenticating parts of XML documents, in response to commercial or security policy considerations.

With XML becoming a major standard for the exchange and sharing of data, many applications now rely on XML to publish and utilize Web data. Data sources (data owners), however often do not have the means to provide high performance query mechanisms, serving hundreds of thousands of client queries per day. Furthermore, it is too costly for them to maintain a secure Web information system infrastructure preventing intruders from tampering with the integrity of the data. As a solution to this problem, data owners can distribute XML document data to data publishers who then handle queries from clients on behalf of the data owners. In this paper, we present a novel authentic publication scheme for XML document data that allows clients to efficiently verify query results from data publishers for correctness and completeness. For this, data owners simply provide summary signatures of their data to clients who then use the signatures in addition to verification objects provided by a publisher to authenticate query results. Our approach supports two of the most common forms of XML queries, path and selection queries. The approach is reliable where no trust from publishers is required, and is practical with a reasonably small overhead, both in terms of time and size of the storage.