An invention for digital authentication is provided. A first timing signal is received from a remote source using a receiver. Next, a delay number is stored. The delay number is based on a first delay time period between when the first timing signal was transmitted and when the first timing signal was received. A digital transaction is then authenticated using the delay number. In one aspect, a digital certificate is created using the delay number. The remote source can be any source capable of generating timing signals, such as a global positioning satellite (GPS) system or a cell tower system. The delay in the timing signal can be caused by free electrons in a line of sight between the remote source and the receiver, such as by variations in atmospheric conditions or by an object within the line of sight such as bird or tree branch. Optionally, the delay number can be stored on a User Card and a System Card. In this aspect, a transaction between the User Card on a client computer and the System Card on a server computer can be authenticating by comparing the delay number stored on the User Card to the delay number stored on the System Card.