Cryptography – Equipment test or malfunction indication
Patent
1992-11-03
1994-04-12
Cain, David C.
Cryptography
Equipment test or malfunction indication
380 49, H04K 100
Patent
active
053032934
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a cryptographic device with a display means for identification of a defective function in the cryptographic device.
BACKGROUND
Cryptographic devices for use with a data terminal in a data network are very sensitive devices with respect to operational reliability. Function errors occurring in the cryptographic device directly affect data transmission in the network. This can lead to a transmission of data with corrupted information, which in some circumstances cannot be immediately detected by the network subscribers. It is therefore necessary to display a malfunction in the cryptographic device immediately.
By the very nature of their function, the design of cryptographic devices is very complex and they cannot be exchanged arbitrarily for reasons of security and cost. It is therefore necessary to detect and to identify immediately any function errors occurring, and to rectify these errors.
It is therefore the object of the invention to design a cryptographic device of the type mentioned at the beginning in such a way that function errors occurring in the cryptographic device can be reliably detected and identified.
SUMMARY OF THE INVENTION
The above object is achieved in a cryptographic device of the mentioned above, in which there is provided an internal monitor device for monitoring the functions of the cryptographic device, and a display device operatively connected to the monitoring device.
By virtue of the fact that the control device for the cryptographic device is assigned an internal monitoring device for independent function monitoring of the cryptographic device, to which monitoring device a display means for identification of a defective function in the cryptographic device by alphanumeric representation is linked, function errors occurring can be reliably detected and identified.
The function checking of the cryptographic device is carried out continuously during operation by the monitoring functions assigned to the monitoring device, the monitoring functions being advantageously hierarchically structured with respect to one another. The structure depends on the significance and on the effect of the function errors that can occur. In general, when an error occurs the control device of the cryptographic device and consequently the cryptographic device itself assumes an error status, and as a result the data transmission is immediately and recognizably interrupted. The malfunction occurring is indicated alphanumerically on an optical display means so that it can be identified immediately by reference to said display means. The display contains here information about the type of fault and the location of its occurrence within the control device or within a control program operating in the control device.
The functioning of the cryptographic device can be checked before data operation commences by means of a self-test routine, which can be triggered by input of "reset" for example. This produces a very high level of reliability for the operation of such a cryptographic device.
BRIEF SUMMARY OF THE DRAWINGS
An embodiment of the invention is illustrated in the drawing and is described in greater detail below by way of example.
The figure shows a diagrammatic block circuit diagram of a cryptographic device with integrated monitoring device and an optical display means.
DESCRIPTION OF THE PREFERRED EMBODIMENT
An error-protected telegraph network illustrated in the figure contains a multiplicity of data terminals DEE in the form of teleprinters or personal computers; for the sake of simplicity, however, only one data terminal DEE is illustrated in the drawing. Each data terminal DEE is assigned a cryptographic device SG, with a transmission cryptogenerator KG-S in a transmission channel S and a reception cryptogenerator KG-E in a reception channel E. The cryptographic devices SG of the various data terminals have the same design as one another. In the case illustrated, the telegraph network is operated in the "half-duplex" traffic mod
REFERENCES:
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patent: 4645871 (1987-02-01), Bremer et al.
patent: 4926475 (1990-05-01), Spiotta et al.
patent: 5161186 (1992-11-01), Dolev et al.
"Data and Voice Encryption", Fujitsu Sci. Tech. J., 22, 4, Sep. 1986, pp. 331-342.
"Die Praktischi Fehlersuche An Geraten Mit Mikrocomputern", Rundfunktech Mitteilungen, vol. 26 (1982) May/Jun., No. 3, Norderstedt, Deutschland, pp. 121-132.
Cain David C.
Siemens Aktiengesellschaft
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