In one embodiment, a computer-implemented method includes, in response to an attempt by a user to perform a transaction using a computing device, accessing a communication device connected to the computing device. A presence of one or more nearby devices, with respect to the computing device, is detected through use of the communication device connected to the computing device. A mapping of nearby devices to trust levels may be applied to the one or more nearby devices. In the mapping, each group of one or more nearby devices maps to a trust level of two or more trust levels. An assigned trust level for the transaction is determined, by a computer processor, based on applying the mapping of nearby devices to trust levels. The mapping of nearby devices to trust levels is modified based on the one or more nearby devices detected. The modified mapping is used for future transactions.