In the cloud environment the digital content accessed by the user is mostly stored in the server. Thus it needs to prevent malicious persons from modifying information and faking the users identity to obtain the digital content. In addition in the cloud computing environment it is required to consider the storage space and computing performance problems for the mobile device. In this paper a secure and efficient NFC identity authentication and digital content protection scheme is proposed. We use an NFC tag to store the security token and other related parameters and put the tags in a protected environment in order to prevent it from being damaged or tampered by malicious persons. Through the NFC side-channel a user needs to near the NFC tag to access the security token. In addition we use the challenge-response protocol and the message authentication code to achieve mutual authentication and generate the session key to protect the transmitted digital content.