JPH0196686A - Code key managing apparatus - Google Patents

Abstract

PURPOSE: To prevent a cipher key from being altered by a third person with ease by inputting switch information on a physical key switch and the comparison output of a specific information comparing means and allowing the cipher key to be written only when the switch information is on and the comparison output indicates a coincidence. CONSTITUTION: The specific information is held by a specific information holding means 21 and the specific information comparing means 22 compares this specific information with externally inputted information. This physical key switch information and the comparison output of the specific information comparing means 22 are inputted to a cipher key writing control means 23 and when the physical key switch 25 is on and the comparison output shows a coincidence, the cipher key held by the cipher key holding means 11 is allowed to be written. Therefore, the physical key switch 25 is turned on with the physical key 24 and only when the coincidence is obtained by the specific information comparing means 22, the writing to the cipher key holding means 21 is allowed. Consequently, it becomes difficult for a person other than a ciphering device administrator to write the cipher key.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a cryptographic key management device for managing cryptographic keys used for encrypting or decoding signals with cryptographic processing means.

``Prior Art'' In the encryption device Kanji, as shown in FIG. 3, the encryption key is held in the encryption key holding means 11, and the
The signal input from the human-powered boat is encrypted or decrypted using the encryption key held by the encryption key holding means 11, and ciphertext or plaintext is output as an output signal.

In this case, the encryption device administrator rewrites the encryption key stored in the encryption*i storage means 11 as necessary. Conventionally, as a measure to distinguish between the cryptographic device administrator and others, the second manual boat for inputting the cryptographic key was configured so that only a special cryptographic key writing device could be connected, and the cryptographic key writing device was only used by the cryptographic device administrator. took great pains to preserve it. The cryptographic key writing device is expensive because it has a special shape. In addition, if the encryption key writing device is not used manually (two people can change the encryption key even if they are not the encryption device administrator), therefore, even if the encryption key is rewritten (encryption key destroyed) by someone who is not the encryption device administrator, recovery is possible. The cryptographic device administrator was required to memorize the cryptographic key in order to be able to do so.

The encryption key is generally stored by the administrator of the encryption device by writing it in a memo or the like. However, in this state, there is a risk that the encryption key will be stolen by someone else, and that the encryption device administrator himself may forget the encryption key. ■ The contents of the file encrypted with the stolen encryption key will be stolen. ■ Encryption key storage means. If the encryption keys stored in the computer are destroyed, there is a risk that the encrypted file assets will become unusable.

"Means for Solving Problems" According to the present invention, specific information is held in the specific information holding means, and this specific information and information input from the outside are compared by the specific information comparing means. On the other hand, a physical key switch controlled by a physical key is provided, and this physical key switch information and the comparison output of the specific information comparison means are input to the encryption key writing control means, and when the physical key switch is on and the comparison output is If they match, writing of the encryption key held in the encryption key holding means is permitted.

As described above, according to the present invention, writing to the encryption key holding means is possible only when the physical key is turned on by the physical key and a match is obtained by the specific information comparison means, so that it is possible for anyone other than the encryption device administrator to write to the encryption key holding means. It becomes difficult to write the encryption key using

Embodiment FIG. 1 shows an embodiment of an encryption key management device according to the present invention, and parts corresponding to those in FIG. 3 are given the same reference numerals.

According to this invention, specific information is held in the specific information holding means 21. The specific information is compared with the information input from the third human-powered boat by the specific information comparing means 22, and a comparison output indicating whether the information matches or does not match is supplied to the encryption key writing control means 23. - A physical key switch 25 controlled by a physical key 24 is provided, and switch information of the physical key switch 25 is also supplied to the encryption key write control means 23.

The encryption key writing control means is the input physical key switch 25.
Only when the switch information is on and the comparison output input from the specific information comparing means 22 is a match, writing to the encryption key holding means 11 is enabled. Note that an encryption key holding battery 26 is provided so that the encryption key in the encryption key holding means 11 is held even if the main power is turned off.

As shown in FIG. 2, inside the box 27, the encryption key holding means 11
The cryptographic processing means 12, the specific information holding means 21, the specific information comparing means 22, the encryption key writing control means 23, and the physical key switch 25 are put in and sealed, and the power switch 28 is inserted from the box 27.
, the keyhole 301 of the physical key 24, the power cord 29, and the data input/output port 31 are removed from the outside. In addition to sealing with the box 27, for example, the encryption key and specific information may be stored in an LSI, and the LSI may be housed in a package.

In this way, if both the physical key and specific information are stolen, the value of the encryption key in the encryption key holding means 11 may be changed, but since the encryption device is sealed inside the box 27, The value of the encryption key cannot be read out, so encrypted files and other information remain confidential.

``Effects of the Invention'' As stated above (according to the 22nd invention, encryption key rewriting control is performed, so easy tampering of the encryption key by another person is prohibited.For example, in the case of a physical key, a person who attempts to tamper with it) Since it is necessary to make a copy of the encryption key 24, this requires a great deal of effort.

In addition, if a person who does not have the right to know the specific information of the encryption device tries to find the specific information by brute force, for example, 64
In the case of bit length, it is necessary to try about half of the 264 ways in terms of probability, so assuming that one trial time is 17420 seconds, (264X 10') / (2X365X24
X3600) ~300,000 years. This makes it almost impossible for someone who does not know the specific information to analyze and search for the cryptographic device.

Moreover, since the encryption key cannot be tampered with unless both the encryption key 24 and the specific information fall into the hands of a person tampering with the key, it is extremely difficult to tamper with the encryption key.

Since what the cryptographic device manager manages is the specific information and the physical key, it can be easily implemented without requiring any special equipment.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing the appearance of a cryptographic device sealed in a box, and FIG. 3 is a block diagram showing a conventional cryptographic device. Patent applicant: Nippon Telegraph and Telephone Corporation Agent: Taku Kusano 871
Hard o 2 decoy

Claims (1)

[Claims] (1) In a cryptographic device that encrypts or decrypts an input signal with a cryptographic processing means using a cryptographic key held in a cryptographic key holding means, a specific information holding means that holds specific information; A specific information comparing means for comparing the held specific information and information inputted from the outside; a physical key switch controlled by a physical key; and a comparison output of the switch information of the physical key switch and the specific information comparing means; an encryption key management device, comprising an encryption key write control means for permitting writing of the encryption key held in the encryption key holding means when the switch information is on and the comparison output is a match.