Database outsourcing is a popular industry trend which involves organizations delegating their data management needs to an external service provider. In this model, a service provider hosts its clients’ databases and offers mechanisms for clients to create, store, update and access (query) their databases. Since a service provider is almost never fully trusted, security and privacy of outsourced data are important concerns. This paper focuses on integrity and authenticity issues in outsourced databases. Whenever someone queries a hosted database, the returned results must be demonstrably authentic: the querier needs to establish – in an efficient manner – that both integrity and authenticity (with respect to the actual data owner) are assured. To this end, some recent work [19] examined two relevant signature schemes: one based on a condensed variant of batch RSA [3] and the other – on aggregated signature scheme by Boneh, et al. [4] In this paper, we introduce the notion of ...