The Internet of Things refers to networks of physical, technological devices connected via the Internet, allowing them to communicate and exchange data. Such environments face security issues like verifying users using Internet of Things devices, for example, in a company or hospital or properly securing user communication. Communication security largely relies on the security of symmetric keys, which we use to encrypt messages. This paper introduces a novel approach to verifying the identity of users of Internet of Things environments and generating symmetric keys between two users to communicate between them. The verification system identifies users using images captured from the camera. Thus, the proposed symmetric keys generation method uses biometric parameters representing the coordinates of a triangle from the two users' faces biometry and the time factors. The triangle coordinates are located between the corners of the left and right eyes and the chin. Then, these coordinates and time factors undergo mathematical processing to obtain an alphanumeric symmetric session key. We tested the entire system, obtaining a high precision score regarding user identity verification, and additionally examined the possibility of breaking the generated symmetric keys. All keys were characterised by high entropy and resistance to brute-force attacks.