Vera D Barnes

US Patent:

41601203, Jul 3, 1979

Filed:

Nov 17, 1977

Appl. No.:

5/852443

Inventors:

Vera L. Barnes - Wayne PA
Thomas J. Dodds - Drexel Hill PA
Harold F. Gibson - Downingtown PA
Carl M. Campbell - Newtown Square PA

Assignee:

Burroughs Corporation - Detroit MI

International Classification:

H04L 900

US Classification:

178 22

Abstract:

An apparatus for insertion in a communications line for providing both message integrity and message secrecy within a significant portion of existing communications networks. At the transmitter end, the apparatus receives messages from the communications line, enciphers them on a bit-by-bit basis and retransmits them onto the communications line. At the receiver end, the apparatus receives messages from the communications line, deciphers them on a bit-by-bit basis and retransmits them onto the communications line. The apparatus contains both a transmitter and receiver and is capable of full duplex operation in a bidirectional communications line. According to the invention, data is enciphered by combining the data received with the output of an algorithm, the algorithm output being responsive to data previously received and a unique key entered by the user. As a data bit is received, it is combined with the output of the algorithm, transmitted, and using cipher feedback techniques fed back as an input to the algorithm to be used to encipher subsequently received data bits. Data is deciphered using equivalent elements as used for enciphering, the basic difference in the apparatus operation being the point from which data fed back into the algorithm is taken.

US Patent:

41722132, Oct 23, 1979

Filed:

Nov 17, 1977

Appl. No.:

5/852444

Inventors:

Vera L. Barnes - Wayne PA
Thomas J. Dodds - Drexel Hill PA
Harold F. Gibson - Downingtown PA
Carl M. Campbell - Newtown Square PA

Assignee:

Burroughs Corporation - Detroit MI

International Classification:

H04L 900

US Classification:

178 22

Abstract:

An apparatus for insertion in a communications line for providing message secrecy within a significant portion of existing communications networks. At the transmitter end, the apparatus receives messages from the communications line, enciphers them and retransmits them onto the communications line. At the receiver end, the apparatus receives messages from the communications line, deciphers them and retransmits them onto the communications line. The apparatus contains both a transmitter and receiver and is capable of full duplex operation in a bidirectional communications line. According to the invention, data is enciphered by combining the data received with the output of an algorithm, the algorithm output being dependent on the data previously enciphered and a unique key entered by the user. As data is received it is combined with the output of the algorithm, transmitted and using cipher feedback techniques fed back as an input to the algorithm to be used to encipher subsequently received data. Data is deciphered using equivalent elements as used for enciphering, the basic difference in the apparatus operation being the point from which data fed back into the algorithm is taken.

US Patent:

41594681, Jun 26, 1979

Filed:

Nov 17, 1977

Appl. No.:

5/852446

Inventors:

Vera L. Barnes - Wayne PA
Thomas J. Dodds - Drexel Hill PA
Harold F. Gibson - Downington PA
Carl M. Campbell - Newtown Square PA

Assignee:

Burroughs Corporation - Detroit MI

International Classification:

H04L 110

US Classification:

3401461AL

Abstract:

A device for insertion in a communications line for verifying message integrity within a significant portion of existing communications networks. At the transmitter end, the device receives plain text messages from the communications line, generates an authentication field by encrypting the plain text message received and retransmits the plain test message received, with the authentication field appended thereto, onto the communications line. At the receiver end, the device receives messages from the communications line, generates an authentication field by encrypting the plain text portion of the message received and compares the authentication field generated with the authentication field appended to the plain text portion of the message received. If the two authentication fields are identical, the plain text message has been received exactly as it was transmitted, and the receiving device will transmit the plain text portion of the message received to the receiving terminal, appending thereto a character indicating message integrity. Similarly, if the two authentication fields differ, the receiving device will transmit to the receiving terminal the plain text portion of the message received with an appended status character indicating that an error occurred during transmission of the plain text portion of the message.