NL8304120A - KEY ENTERING DEVICE FOR ENCRYPTION AND DECRYPTION DEVICES FOR SECRET INFORMATION TRANSFER. - Google Patents

Description

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Key input device for encryption and decryption devices for secret information transfer.

The invention relates to a key input device for encryption and decryption devices for secret information transfer as well as for key resource memories in key distribution centers, the key input device being the size of a packet of cigarettes.

Key input devices mainly serve to distribute and transport a key, in other words to manage the key.

For example, a key input device is known from the company prospectus of AEG-Telefunken Backnang, Datatechnik, 10 "Photoelektrischer Lochstreifenleser", which uses as key-holder a relatively short apertured strip which is pulled manually by the device. case known with the key because the key can be either written down or copied, and it is also possible to read the key without authorization without detecting such abuse. ψ

The object of the invention is now to provide a key input device which considerably increases the security against misuse compared to known key input devices because the operating personnel no longer have access to the key information and the unauthorized reading of the key can subsequently be detected by control measures.

This objective is achieved through the measures outlined in the attached main claim. The subclaims relate to preferred embodiments.

The invention is explained in more detail below with reference to an exemplary embodiment, with reference to the accompanying figure.

The figure shows the functional diagram of a key input device according to the invention.

The key input device according to the invention can be loaded in a key-counting exchange with a large number of different keys. The input device offers the possibility to enter certain keys for each key-powered key device in accordance with a distribution plan. The key input can then take place under the control of a program. It is therefore no longer necessary that in such a case several key carriers (e.g. punch tapes) are read into the key device.

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The key transport is easy. Instead of a large number of key carriers, only the key input device need be transported. In an emergency, the keys can be destroyed at the touch of a button. Mechanical key carriers cannot be so easily destroyed.

An organizational plan lays down how often the individual keys must be read in, and it is therefore easy to test, for example in the key distribution center, via an indication on a display device, how often the individual keys have actually been read from the key input device. The risk of compromise is considerably less with this electronic monitoring.

Four pushbuttons are provided for key selection: a) key selection 15 b) operating mode selection c) start d) emergency erase.

The different operating states and dialing values are displayed on an alphanumeric display panel of, for example, 20 four positions.

The display panel is used to visualize mnemonic expressions such as "BATT" or "TEST" as well as to visualize company types and key numbers. Business types are shown with letters in two positions on the left side of the display screen, and key numbers are also displayed with numbers in two positions on the right side of the display screen.

The key selection takes place with a separate push button, the two-position key number of the selected key being shown on the right of the display. The selected key can be changed depending on the set operating type.

The start button starts processing the procedure, which always belongs to the selected operating mode.

The starting position arises after the supply voltage is switched on in the device if at that moment the buffer voltage for the key memory is present, i.e. charged batteries for buffering the key memory are connected in the device and if the key protection means are not being active.

The automatically-adjusted starting position after switching on the device ensures that the operating mode "key erase-40 sen" is not accidentally set and that key information is not accidentally erased due to operating errors.

The originally set key is selected again after the supply voltage is switched on and its key number is displayed, which means that interruptions of the supply voltage do not lead to a change of the key and that no new key selection is necessary.

The error recognition during the key input can take place in various ways: a) a monitoring device can test, for example, by evaluating a test characteristic derived from the key, whether errors have occurred during the key reading. Depending on the key, the test characteristic can be calculated using the key input device itself and stored together with the key.

B) a further possibility is that a master key is stored in the key input device and the key to be used is encrypted with the master key in the key input device itself. The master key can then be erased again, because the master key is known in the encryption or decryption equipment to be fed. In addition, the security against misuse has been increased again, because the individual keys themselves are only encrypted in the key input device.

The battery test can only be carried out with the supply voltage switched on. The test is performed such that the batteries are loaded for a few milliseconds by a predetermined load. An indication of the condition of the batteries is derived from the voltage change that occurs under load.

However, a battery change requires the rereading of the key information, because a battery change leads to the activation of the key security means and thus to the loss of key information.

A clearing process for the key memory is performed by selecting the appropriate operating mode in combination with the start key. The display for "free memory location" is displayed on the display panel.

Emergency deletion, where the entire key memory content is deleted, is initiated by pressing the appropriate "emergency erase" key. Such an emergency deletion is possible 40 even when the key input device is not connected 83 04 1 2 0 .

4 on the supply voltage.

8304120

Claims (11)

1. Key input device for encryption and decryption devices for secret information transfer as well as for key resource memories in key distribution centers, the key input device being the size of a pack of cigarettes, characterized by the combination of the following sub-features: that a microcomputer is present which controls the functions of the key input device, b) that an electronic key memory is present which can be loaded with a large number of different keys, c) that push buttons are present, by means of which the operating mode or the key can be respectively d) that there is a display panel with which an indication of the operating type, the key number and other messages is visible, e) that a coupling circuit for input and output of keys is present, f) that an independent power supply by batteries for buffering of the key memory is present. Key input device according to claim 1, characterized in that a self-powered battery supply for operating the key input device is provided. Key input device according to claim 1, characterized in that all keys in the key memory can be erased by pressing a button, because a "zero" is written in each memory cell. Key input device according to claim 1, characterized in that a counting device is present which indicates on the display panel how often a key has been read. Key input device according to claim 1, characterized in that, in accordance with the key devices to be fed, certain keys can be entered according to a distribution plan and can be read out accordingly. 6. Key input device according to claim 1, characterized in that a noise generator can be connected via the coupling circuit, so that keys of different sizes can be generated in the key input device itself by selecting the operating type. Key input device according to claim 1, characterized in that the key input device can be used as a multiple memory of the key device when it is permanently connected to a key device. Key input device according to claim 1, characterized in that the contents of the key memory can be erased by means of an emergency switch independent of an external power supply. Key input device according to claim 1, characterized in that a monitoring device, after key input, by evaluating a test characteristic derived from the key, tests the key for absence of errors. 10. Key input device according to claim 1, characterized in that during the key formatting in the key input device a key-dependent test characteristic is calculated and stored with the key. Key input device according to claim 1, characterized in that a master key is stored in the key input device and that the keys in the key input device are encrypted with this master key and only then are stored. ******** 8304120