In this paper, we present C-ABSC, a cooperative privacy preserving attribute based signcryption mechanism. It consists on performing the combined signing and encrypting processes of a set of data devices' inputs in a secure collaborative manner. The main idea behind C-ABSC relies on the distribution of the signcrypting operation among different devices, with respect to selected sub-sets of a general access predicate, such as an untrusted aggregating entity is capable of decrypting the received aggregated data only if a sufficient number of IoT devices cooperates. The C-ABSC scheme is multifold. First, it provides a selective access to authenticated aggregated data contents. Second, it provides a privacy preserving signcrypting process, such that a curious aggregator can neither infer the used IoT device's attributes for signing nor deciphering single data chunks. Third, C-ABSC relies on low computation and communication processes, mainly for resource-constrained devices.