Some examples include determining a plurality of motion pattern readings detected by an electronic device in conjunction with entry of a passcode on the electronic device, such as for authentication of a transaction. The passcode may be entered as a sequence of tactile presses on the electronic device, and the detected motion pattern readings may be indicative of movements of the electronic device when the tactile presses occur. Based at least in part on the motion pattern readings, a plurality of locations corresponding to the tactile presses may be determined. Further, based at least in part on the determined plurality of locations, symbols for the passcode may be determined. In some cases, a process for authenticating the transaction may be initiated using the determined passcode.