Showing papers on "On-the-fly encryption published in 1983"

File access security method and means

Abstract: An improved file access security technique and associated apparatus accesses data which is stored in encrypted form under one encryption key and re-stores the data re-encrypted under another encryption key, and produces a record of each access and data re-encryption both as the control source of encryption keys for access and re-entry of encrypted data and as a secured audit record of users that had access to each file.

User authentication system employing encryption functions

Abstract: A system which employs a pair of encryption functions f and g in the "log on" protocol of a computer dial-up arrangement. The functions are inverses of each other and, hence, a random sequence when encrypted with f and then with g results in the original sequence. When a user wishes to "log on", the computer selects a random sequence and forms a challenge sequence. The user encrypts the challenge sequence with the function g and thus forms a response sequence. Encryption with the function f by the computer permits verification of the response sequence. The secrecy of the user's function is maintained by providing the user with an authenticating device having only two ports: a power port and an I/O port. The I/O port is connected to a microprocessor which accesses a memory that contains the secret encryption function g.

Recursive key schedule cryptographic system

Abstract: An encryption system in which a code word is processed, byte by byte, by a Vernan type process followed by non-linear encryption techniques, all of which are repeated several times, to generate a working key schedule. This key schedule is then used in the same process to encrypt the text.

Encryption and decryption (scrambling and unscrambling) of video signals

Abstract: A video signal is encrypted by pseudo-random variation of portions of lines thereof to be horizontally scanned that are devoid of video information. Thus, the durations of line blanking intervals may be varied. The variation is done in accordance with an encryption keys which is employed at the receiver to decrypt the encrypted video signal.

Modified Architecture for the Sub-Keys Model

Abstract: A secure implementation for subkey database encryption is presented. Both Vertical and Horizontal access to the control encrypted date are defined and described. Communication protocols between user and system are also provided.

Improvements in and relating to autoteller systems

Abstract: An autoteller system 10 comprises an encryption module 30 for encrypting and decrypting data on user cards and for encrypting and decrypting data communicated between it 10 and a remote host 22. The system is characterised by a key loader 58 containing algorithm performance instructions on a ROM 88 removably connectable to the encryption module 30 for the generation of a master key for an encryption circuit 152 to use the master key to encrypt a sub-key for the encrypted sub-key to be used as a session key when encrypting or decrypting data from a user card. The system is further characterised by the keys being stored in a battery-maintained RAM 108 which is volatile if the encryption module 30 is removed. The system is further characterised by the host 22 being operable to provide the autoteller 10 with a plurality of communication keys where any selected named communication key can be used for encrypting and decrypting data communicated between the system 10 and the host 22. The system 10 is yet further characterised by the communications keys supplied to the system 10 being the result of encryption of decryption by the encryption module 30 of sub-keys from the host 22.

Method of synchronising encryption and decryption during the transmission of digital encrypted data, and apparatus for carrying out said method

Abstract: Bei einem Verfahren und einer Vorrichtung zum Synchronisieren der Verschlusselung und Entschlusselung beim Ubertragen verschlusselter Daten werden nach einer Startsynchronisation in mehreren Zeitschlitzen des empfangenen Datenstroms Korrelationen mit mehreren gleichartigen, empfangsseitig erzeugten und zeitlich gegeneinander versetzten Synchronisiersignalfolgen durchgefuhrt. Durch Korrelation einer dieser Folgen mit der identischen, sendeseitig periodisch in den Datenstrom eingeblendeten Synchronisierfolge wird der Zustand der Synchronisation uberwacht und gegebenenfalls korrigiert. Das erfindungsgemasse Verfahren kombiniert die Vorteile einer Dauersynchronisation mit der schnellen Wiederherstellung der Synchronisation nach Ubertragungsstorungen.