The low prices on cloud data storage and sharing services incentive users to outsource their data to the cloud. Because data stored in the cloud may be lost or corrupted, users are suggested to verify data integrity before the utilization of cloud data. A series of schemes have been proposed to enable a public verifier to efficiently check the correctness of cloud data without downloading the whole data from the cloud server. Unfortunately, few of them have considered about public verification on multi-owner cloud data while still preserving identity privacy of owners from public verifiers, where each block in these cloud data should be signed by multiple owners. In this paper, we design a novel public verification scheme to audit the integrity of multi-owner data stored in the cloud. With our scheme, a public verifier is able to efficiently check the integrity of multi-owner data with a very small communication cost compared with the size of the entire data. Meanwhile, the private identities of these owners are protected and not revealed to any public verifier. In addition, our scheme can also efficiently support group dynamics for multiple owners and enable batch verification. Security analyses and experimental results indicate our scheme is correct, secure and efficient. Copyright © 2013 John Wiley & Sons, Ltd.