Nowadays, IOT (Internet Of Things) devices are everywhere and are used in many domains including e-health, smart-cities, vehicular networks,.. etc. Users use IOT devices like smartphones to access and share data anytime and from anywhere. However, the usage of such devices also introduces many security issues, including in data sharing. For this reason, security mechanisms such as ABE (Attribute-Based Encryption) have been introduced in IOT environments to secure data sharing. Nevertheless, Ciphertext-Policy ABE (CP-ABE) is rather resource intensive both in the encryption and the decryption processes. This makes it unadapted for IOT environments where the devices have limited computing resources and low energy. In addition, in CP-ABE, the privacy of the access policy is not assured because it is sent in clear text along with the cipher-text. To overcome these issues, we propose a new approach based on CP-ABE which uses fog devices. The letters collaborate to reduce the bandwidth, and partially delegates data decryption to these fog devices. It also ensures the privacy of the access policy by adding false attributes to the access policy. We also discuss the security properties and the complexity of our approach. We show that our approach ensures the confidentiality of the data and the privacy of the access policy. The complexity is also improved when compared with existing approaches.