Nowadays, lots of location and time critical data has been collected by Internet of things (IoTs), such as intelligent fire control, intelligent transportation, environmental monitoring and so on. It is well known that the location and time information of these data will play an important role on some applications in IoTs. For example, the time and location information is generated in the fire alarm system, vehicle system and UAV data acquisition system. However, how to guarantee the security of these spatio-temporal data has become a challenge. One hand, the property of the data integrity should be provided; the other hand, the location and time information of the data origin should be unforgeable. This study investigates position based signatures as one of the solutions to the security of the spatio-temporal data in IoTs. Firstly, the static position based digital signature without considering time and the dynamic position based digital signature with time constraint is proposed respectively. Then, a position based digital signature protocol based on the bounded retrieval model in 3-dimension is proposed which satisfies the security requirements of dynamic conditions. Furthermore, by analyzing the security of our protocol, we conclude that the proposed protocol can resist collusion attack of the adversaries and satisfy the provable security.