As Infrastructure as a Service (IaaS) cloud becomes increasingly important to all stakeholders; the evaluation on the degree of trust of the IaaS cloud remains a challenge. This study aims to discover and identify the Common Trust Criteria (CTC) from context-based trust and context-based cloud and later organized, discussed, compared, and aggregated a conceptual model of CTC in an impartial manner. The main purposes of CTC model are: (a) to provide Cloud Service Requesters (CSRs) with a CTC model with which to evaluate the degree of trust that can be placed in IaaS cloud (b) to provide guidance to Cloud Service Providers (CSPs) as to what to build into their new, widely-available trusted IaaS cloud in order to satisfy trust requirements. To do so, a systematic review on context based trust and context-based cloud is provided. The results indicated that there was an important set of trust criteria such as Integrity, Benevolence, and Reputation that were neglected from the current research related to cloud. © 2014 IEEE.