1. A method for authenticating packets transmitted serially in a network, comprising: selecting a current password P i for a current packet to be transmitted, the current packet including current data M i ; applying a one-way/one-time hash function h to the current password P i to form a current tag Y i of the current packet as Y i+1 =h(P i+1 ); selecting a next password P i+1 for a next packet to be transmitted, the next packet including next data M i+1; applying the one-way/one-time hash function h to the next password P i+1 to form a next tag Y i+1 of the next packet as Y i+1 =h(P i+1 ); applying the one-way/one-time hash function h to the next data M i+1 the next tag Y i+1 , and the current password P i of the current packet to obtain Z i+1 =h(M i+1 , Y i+1 , P i ); and transmitting the current packet, the current packet including Z i+1 , the current data M i , the current tag Y i , and a previous password P i−1 , of a previously transmitted packet to authenticate the current data M i .