초록 ▼

In order to improve the security of message transmission from a terminal apparatus in an electronic banking or other data communications system a check-sum or MAC is computed from the data within the message in dependence upon a cryptographic key. This MAC is issued as a “challenge”to the user who i

In order to improve the security of message transmission from a terminal apparatus in an electronic banking or other data communications system a check-sum or MAC is computed from the data within the message in dependence upon a cryptographic key. This MAC is issued as a “challenge”to the user who is also equipped with a separate portable token for computing a “response”in dependence upon a second cryptographic key which is unique to his token. This “response”is then entered into the terminal and appended to the message as its authentication code before transmission. A recipient of the message and authentication code equipped with the same cryptographic keys can therefore check both the contents of the message and the correct identity of the sender by computing an expected authentication code from the received message and comparing it with the code received.

대표청구항 ▼

A method of secure message transmission from a terminal apparatus to a remote receiving station in a communications system, which involves appending to a message to be transmitted an authentication code comprising substantially fewer data bits than in the message and the value of which depends upon

A method of secure message transmission from a terminal apparatus to a remote receiving station in a communications system, which involves appending to a message to be transmitted an authentication code comprising substantially fewer data bits than in the message and the value of which depends upon both the information in the message and information representing the identity of the sender, and wherein the authentication code is produced by a method comprising the steps of: computing within the terminal apparatus by first processing means a first code the value of which depends upon the information within the message and comprising substantially fewer data bits than in said message; issuing that code to the sender; computing a second code from said first code and from information representing the identity of the sender, said second code comprising substantially fewer data bits than in said message, by second processing means within a token assigned to the sender and which means can be actuated to perform the computation of said second code only upon recognition of a correct input indicative of the authority of the sender; and entering said code into the terminal apparatus, that code or a derivative thereof constituting the authentication code; and which comprises at the receiving station repeating the computation of an authentication code from the received message by means replicating the computations of said first and said second processing means, and comparing the authentication code thus computed with the authentication code received, thereby to permit authentication of the received message and of the identity of the sender.