In Named Data Networking (NDN), security is imposed on contents instead of end-to-end connections; therefore, every content contains a signature to prove its authenticity and integrity. While this property has many significant advantages, it causes big message overhead in some cases, especially if the content size is small. This overhead further increases if the content is generated by multiple authorities, e.g., in a moderator-controlled information sharing service, and needs to contain multiple signatures. We propose the use of Identity-Based Aggregate Signatures (IBAS) to decrease this overhead. Also, we provide a proof-of-concept IBAS implementation in NDN and compare its performance with existing Public Key Infrastructure RSA signatures.