Secure computer interface

• US 5,272,754 A
• Filed: 03/28/1991
• Issued: 12/21/1993
• Est. Priority Date: 03/28/1991
• Status: Expired due to Term

• Current Assignee: Secure Computing Corporation (McAfee, LLC)
• Original Assignee: Secure Computing Corporation (McAfee, LLC)
• Inventors: Boerbert, William E.
• Primary Examiner(s): Swann, Tod R.
• Application Number:
  US07/676,885
• Time in Patent Office: 999 Days
• Field of Search: 380/23, 380/24, 380/25, 380/49, 380/4, 380/47
• US Class Current: 713/159
• CPC Class Codes: G06F 21/34 involving the use of external additional devices, e.g. dongles or smart cards
• CPC Class Codes: G06F 2211/009 Trust
• CPC Class Codes: H04L 2209/26 Testing cryptographic entity, e.g. testing integrity of encryption key or encryption algorithm
• CPC Class Codes: H04L 9/0656 Pseudorandom key sequence combined element-for-element with data sequence, e.g. one-time-pad [OTP] or Vernam's cipher
• CPC Class Codes: H04L 9/3234 involving additional secure or trusted devices, e.g. TPM, smartcard, USB or software token network architectures or network communication protocols for supporting authentication of entities using an additional device in a packet data network H04L63/0853

Abstract

Communication elements for secure data communication between remote nodes of a computer system on a standard communications medium. Terminals, workstations and personal computers are connected through a user-side terminator to a standard unsecured communications medium. Processors are connected through a computer-side terminator to the same medium. The combination of a user-side terminator, a computer-side terminator and a standard communications medium constitutes a secure computer interface.

Claims

1. A method of continual mutual authentication in communication over an unsecured communications medium between a data entry node, including a token reader, and a multi-level secure computer having a Secure Kernel, the method comprising the steps of:

providing a user token which can be used to gain access to the multi-level secure computer, wherein the user token comprises data including identifier data characteristic of an individual and a countersign stored from a previous access by the individual;

inserting the user token into the token reader;

transferring, form the data entry node to the multi-level secure computer, a user authorization request including the stored countersign and the identifier data read from the inserted user token;

verifying that the individual associated with the inserted user token has permission to access the multi-level secure computer;

calculating, in the Secure Kernel of the multi-level secure computer, a new countersign;

if the individual has permission to access the multi-level secure computer, transferring, from the multi-level secure computer to the data entry node, a user authorization acknowledgement including the new countersign;

tagging each message from the multi-level secure computer to the data entry node with the new countersign; and

storing the new countersign in the user token.

2. The method according to claim 1 wherein the step of verifying that the individual has permission to access the multilevel secure computer comprises:

comparing, at the computer, the stored countersign to a countersign saved from the individual'"'"'s previous access; and

if the old countersign and the stored countersign are different, sending a countersign failure message to the data entry node and denying permission for the individual to access the computer.

3. The method according to claim 1 wherein the data entry node comprises:

a data entry unit; and

a user-side terminator connected between the data entry unit and the unsecured communications medium, the user-side terminator comprising;

first communications interface means for controlling the transfer of data between the user-side terminator and the data entry unit;

second communications interface means for controlling the transfer of data between the user-side terminator and the unsecured communications medium; and

encryption/decryption means for selectively encrypting data to be transferred onto the unsecured communications medium and for decrypting data received from the unsecured medium; and

wherein the step of transferring a user authorization request comprises the steps of;

providing, between the multi-level secure computer and the unsecured communications medium, a computer-side terminator comprising;

first communications interface means for controlling the transfer of data between the computerside terminator and the multi-level secure computer;

second communications interface means for controlling the transfer of data between the computerside terminator and the unsecured communications medium; and

encryption/decryption means for selectively encrypting data to be transferred onto the unsecured communications medium and for decrypting data received from the unsecured medium;

encrypting the user authorization request at the user-side terminator;

transferring the encrypted user authorization request over the unsecured communications medium to the computer-side terminator;

decrypting the encrypted user authorization request; and

transferring the decrypted user authorization request to the multi-level secure computer.

4. A method of secure data transfers in communication between data entry units nd computers in a computing system having a plurality of nodes, wherein each node includes a data entry unit or a computer and wherein the nodes are connected via an unsecured communications medium, the method comprising the steps of:

providing a user token which can be used to gain access to a node of the computer system, wherein the user token comprises identifying characteristics of a particular user and a countersign stored from a previous access;

providing a plurality of communications elements which can be installed at a node to increase security in data transfers between nodes equipped with communications elements, wherein a communication element can be installed at a node by inserting the communications element between a data entry unit or computer and the unsecured communications medium and wherein each communications element comprises;

first communications interface means for controlling the transfer of data between the communications element and its associated data entry unit or computer;

second communications interface means for controlling the transfer of data between the communications element and the unsecured communications medium; and

encryption/decryption means for selectively encrypting data to be transferred onto the unsecured communications medium and for decrypting data received from the unsecured medium;

installing a first and a second communications element at a first and a second node, respectively;

reading, at the first node, the user token;

transferring, form the first node to the second node, a user authorization request including the stored countersign and one or more of the identifying characteristics read from the user token;

verifying that the user at the first node has permission to access the data entry unit or computer at the second node;

if the user has permission to access the second node data entry unit or computer, transferring, from the second node to the first node, a user authorization acknowledgement including a new countersign; and

storing the new countersign in the user token.

5. The method according to claim 4 wherein the step of verifying that the user has permission to access the second node data entry unit or computer comprises:

comparing, at the data entry unit or computer at the second node, the stored countersign to a countersign saved from the user'"'"'s previous transaction; and

if the stored countersign and the saved countersign are different, sending a countersign failure message to the first node and denying the user permission to access the second node data entry unit or computer.