Abstract: A handheld electronic device enables securely transferring control of a valuable asset associated with a code. The device includes a processor, non-transitory data storage, and a communication component configured to transmit data external to the device. A case houses the components, and is mechanically tamper evident. Software stores within the data storage at least one code, prevents transmission of any code through the communication component without authorization by the user, invalidates the association of a particular code with respect to a particular asset when the software carries out at least one of (i) authorizing transmission of the particular code, and (ii) authenticating a valid transaction using the particular code and authorizing transmission of the digital signature through the communication component.