A system, method and device for detecting keystroke entries in a field entered by keyboard in connection with an online transaction that may be fraudulent or erroneous. A score can be assigned to a keystroke based upon its distance from another keystroke. The scores of keystrokes in a string can be summed to obtain a string score. The string score can be normalized by dividing the string score by the number of keystrokes summed to obtain the normalized string score. A risk of fraud or error can be determined based upon the value of the normalized string score in comparison to a predetermined value.