JPS6182546A - secret communication method - Google Patents

Abstract

PURPOSE:To attain the security of information without complicating an enciphering algorithm by transmitting an optional key to some information processor from a key managing center, holding its key by the information processor which has received it, also transmitting it to the other device through a speaking circuit, and securing a protocol for enciphering the information, between both the processors. CONSTITUTION:A key table is stored in a key table store part 51 of a key managing center 50, and an optional key in said table is determined by a key determining part 52, and transmitted to an information processor 10 by a key transmitting part 53. The key transmitting part 53 transmits a key at every one unit or plural units of a communication sentence, for instance, to the information processor 10. In the information processor 10, the key transmitted from the key managing center 50 is held in a cipher decoding part 11, and the key concerned is transmitted to a terminal equipment 30 holds the transmitted key concerned in a cipher decoding part 31. In this way, a protocol of enciphering is secured between the information processor and the terminal equipment 30.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a secret communication system, and more particularly, to a method for managing cryptographic keys used in this type of secret communication system.

[Background of the invention]

With the development of computer network systems that connect computer systems via communication networks, the need to protect the confidentiality of information on networks has increased. Encryption methods are effective as a means of protecting the confidentiality of information, and various cryptographic algorithms have been proposed to complicate the encryption of one message (for example, Japanese Patent Publication No. 54-35
No. 441.

(See Special Publication No. 5/1-30602). However, if the encryption is #L coarse, the overhead required for encryption will increase, and as a practical matter, the hardware and software devices will also become larger, and the cost will also increase.

Therefore, the encryption algorithm should be kept to a moderate level of complexity.
And 8 pieces of information! It is desired to realize a secret communication method that guarantees confidentiality.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a highly practical secret communication method that can achieve information security without making the encryption algorithm too complicated.

[Summary of the invention]

The effectiveness of encryption lies in the fact that a legitimate user can achieve the intended purpose before the encrypted information can be decoded by a third party. There are two ways to achieve this: the first is to make the encryption algorithm more complex, and the second is to frequently change the encryption key. The present invention focuses on the second method, and comprehensively manages encryption keys at a key management center.
This makes it easy to realize variations in the frequency of sending encryption keys to the host system, key changes, etc.

[Embodiments of the invention]

An embodiment of the present invention will be described in detail below with reference to one drawing. FIG. 1 shows the overall configuration of an embodiment of the present invention.

In FIG. 1, an information processing device 10 is connected to a terminal device or another information processing bag @30 (hereinafter referred to as a terminal) through a communication line 20. The information processing device 10 includes an encryption/decryption unit 11, and the terminal device 30 also includes an encryption/decryption unit 31. The information processing device 10 is further connected to an @management center 50 via a communication line 40. here,
The key management center 50 is the center of the present invention, and includes @table storage section 51, key determination section 52. It consists of a key delivery unit 53.

A key table is stored in the health table storage unit 51 of the simple management center 50, and any key among them is stored in the key determination unit 5.
2, and the key delivery unit 53 sends the information processing device lO
delivered to. The key delivery unit 53 is 1, for example, information processing device 1
Deliver the key to 0 for each message 1A 1st place or multiple units. In the information processing device 10, the key delivered from the key management center 50 is held in the encryption/decryption unit 11, and the key is transferred to the terminal device 30 via the communication line 20 in order to synchronize the encryption with the terminal device 30. Deliver. The terminal device 30 is
By retaining the delivered key in the encryption/decryption unit 31, an encryption protocol is established between the information processing device IO and the terminal device 30. In FIG. 1, the delivery route of this key is shown. Indicated by a broken line.

Here, in the key management center 50, the key table storage section 51
The key variations are displayed in the key selection section 52, and the key selection bar 11 is displayed in the key determination section 52.
The key management center 50 is able to issue comprehensive and comprehensive key delivery instructions for the entire computer network system. The operation will be explained using a specific example, and FIG. 2 shows communications sent and received between the information processing device 10 and the terminal device 3o. Correspondence M.

consists of any number of character strings. In Figure 2, A to F (
It consists of 1' + 5 characters. The first character is I
In Figure 3, the key number and its corresponding sister content are t.
′If), the key table K. It shows and is. In FIG. 3, for example, key number 1 (K,) indicates that the character at address b is to be placed at the beginning of the message.

The table l (1, is the key table of the key management center 5o (
It is stored in each handle part 51, and the key number and its counterpart, j
,: You can arbitrarily select and change the content to be used (1
Issei Table K who is Hi. is given to the key determination unit 52 as 1ηI゛・
The key number for fl is determined by a method using random numbers or by a method specified by the user. Key determination unit 52
The key number determined in is sent to the key delivery unit 53 together with the key contents. The key delivery unit 53 sends the '@ number and the key content to the encryption/decryption unit 11 of the information processing device 10 and the encryption/decryption unit 11.
, is delivered to the encryption/decryption unit 21 of the terminal device 1!730 via the communication line 2o.

, 2, in order to achieve cryptographic synchronization between the encryption/decryption units 1 and 31, a synchronization code is added to the key number and delivered. For example, the serial number or time of the message is used as the synchronization code.

When a message M is sent from the information processing device 10 to the terminal device 3o, the encryption/decryption section 11 sends the key contents from the key sending section 53 to the B number. The processed message j in Figure 2, ] message M, is converted to M in Figure 4.
, and sends it to the terminal device 30. On the other hand, terminal device 3
The decryption unit 31 of o converts the sent M to the original M.
The haiku table shown in FIG. 3 is only one example, and it goes without saying that various variations can be considered. Furthermore, if the key table is given in advance to the encryption/decryption unit 11゜3I of the information processing device 10 or the terminal device 30, the 5-key management center 50 only needs to send the key number and the synchronization code, and the key contents can be Delivery can be omitted.

〔Effect of the invention〕

According to the present invention, since encryption keys are centrally managed in a key management center, arbitrary changes such as key delivery frequency and key changes can be easily made, and information can be kept confidential without complicating the encryption algorithm. Protection is achieved.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention, FIG. 2 is a diagram showing an example of a message, FIG. 3 is a diagram showing an example of a key table, and FIG. 4 is a diagram of an encrypted message. It is a figure showing an example. IO...information processing device, 20...communication line. 30...Terminal device or information processing device. 50...Key management center. Figure 1 Figure 2 Figure 3 Figure 4 ・

Claims (1)

[Claims] (1) In a computer network system that connects information processing devices through communication lines and transmits data between the information processing devices, a key management center that manages keys that instruct the encryption of information (hereinafter referred to as encryption keys) It is installed separately from the information processing device, and the key management center delivers an arbitrary key to a certain information processing device, and the information processing device that receives the delivery holds the key and sends it to the other device through a communication line. A secret communication method characterized by establishing an information encryption protocol between both processing devices.