Method of providing digital signatures

In a method of providing a digital signature of the type which generates a secret number X.sub.i, computes Y.sub.i =F(X.sub.i) where F( ) is a one way function, authenticates Y.sub.i and F( ) at the receiver and transmits X.sub.i to the receiver as the digital signature, the improvement characterized by:

• the step of
• selecting an authentication tree with an authentication tree function comprising a one way function of the Y.sub.i ;
• authenticating at the receiver the root of the authentication tree and the authentication tree function;
• transmitting from the transmitter to the receiver the Y.sub.i and the corresponding authentication path values of the authentication tree;
• and
• authenticating the Y.sub.i at the receiver by computing the authentication path of the authentication tree between the Y.sub.i and the root of the authentication tree.