A method, system, and computer program product for dynamic password-less user verification in a mobile device are provided in the illustrative embodiments. Using a processor and a memory in the mobile device, a first portion of a call log stored in the mobile device is selected. Using a transformation function, a first transformed value corresponding to the first portion is obtained. A second portion of a call log stored in a repository of a service provider is obtained from the service provider, the service provider facilitating voice communications from the mobile device, and the second portion corresponding to the first portion. Using the transformation function, a second transformed value corresponding to the second portion is obtained. Responsive to the first transformed value matching the second transformed value within a tolerance limit, a conclusion is generated that the user verification is successful.