JPH01122227A - Transmission equipment - Google Patents

Abstract

PURPOSE:To perform ciphering processing corresponding to the security of a document by providing plural ciphering means different in degree of ciphering in the transmission side. CONSTITUTION:A ciphering processing part 3 is provided with plural ciphering means 3A-3C different in degree of ciphering, and respective means are selected by a pair of select switches 4 and 5. The ciphering means to be selected is determined based on a selection signal supplied to a terminal 6. A cipher key is connected to the terminal and this cipher key K1 is a key code freely selected by an operator. Since the degree of ciphering is changed by a ciphering circuit, contents of the ciphering circuit are different by ciphering means 3A-3C.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transmission device such as a facsimile machine that uses a line to send and receive information signals, and particularly to a transmission device having a secret function.

[Background of the Invention] In a transmission device such as a facsimile machine that uses a line to transmit information signals, when the information signal to be transmitted is highly confidential, It is necessary to transmit data while maintaining confidentiality only to certain locations.

In order to meet these demands, devices have been developed that encrypt and transmit information signals.

An example of a facsimile machine having such an encryption function will be described with reference to FIG.

An information signal (such as a document) is supplied to terminal 1, and this
After being converted into a predetermined digital signal by the /D converter 2, the encoder 3 performs a predetermined encryption process.

The encrypted information signal is converted into a signal suitable for the transmission format by a modulator 7, and then sent to a line (not shown) through a terminal 8.

As shown in the figure, the encryption device 3 includes a single encryption means 3A.
and a pair of selection switches 4 and 5 provided at the front stage and the rear stage thereof.

Information (=
Whether or not to encrypt the code is selected, and if encryption is to be performed, the pair of selection switches 4.5 are switched as shown. As a result, the information signal is subjected to predetermined encryption processing.

On the receiving side, a predetermined information signal is reproduced by decoding this encrypted information signal based on a predetermined procedure.

[Problems to be Solved by the Invention] By the way, in the case where the encryption device 3 is configured to perform predetermined encryption processing on the information signal and transmit it on the transmitting side, conventionally That's because only a single encryption means 3A is provided! ! This method has the disadvantage that it is not possible to perform appropriate encryption processing depending on the degree of confidentiality of the signal.

In other words, if the encryption strength is controlled according to the confidentiality of the document, the encryption processing will be performed with higher precision.

Normally, confidentiality is ranked as Top Secret, Company Secret, Internal Confidential, etc., so if it is possible to change the encryption strength according to the degree of confidentiality, it would be possible to change the encryption strength. It is clear that the confidentiality of information signals transmitted by

However, since the conventional method has only a single encryption means 3A, there has been a drawback that encryption corresponding to the confidentiality of the document cannot be performed.

Therefore, the present invention proposes a transmission device having an encryption function that can correspond to the degree of confidentiality of documents.

[Technical means for solving the problem] In order to solve the above-mentioned problem, the present invention uses multiple encryption systems with different encryption strengths to ensure the confidentiality of information signals to be transmitted. and a selection means for selecting one of the plurality of encryption methods, and is characterized in that the encryption method is selected in accordance with the confidentiality of the information signal.

[Work] The content of the encryption strength is selected by the user.

Based on this, a plurality of encryption means having different encryption strengths are selected.

Therefore, by selecting an encryption method according to the confidentiality of the document, the confidentiality can be ensured accordingly, and problems such as information leakage can be eliminated.

For example, when transmitting documents with relatively low confidentiality such as company secrets, it is sufficient to select an encryption method with weak encryption strength, and when it is necessary to maintain the highest level of confidentiality, The encryption method with the strongest encryption strength can be selected.

By doing so, transmission is performed that meets the required confidentiality, and the problem of information leakage can be solved at once.

[Embodiment] Next, a case in which an example of the transmission device according to the present invention is applied to the above-mentioned facsimile machine will be described in detail with reference to FIG. 1 and subsequent figures.

In FIG. 1, an information signal (signal of a document, etc.) supplied to a terminal 1 is converted into a predetermined digital signal by an A/D converter 2, and then subjected to predetermined encryption processing in an encryption device 3. be done.

The encrypted information signal is converted into a signal in a predetermined format by the modulator 7, and then sent to the line side through the terminal 8.

As shown in the figure, the encryption device 3 has a plurality of encryption devices with different encryption strengths,
In this example, three encryption means 3A to 3C are provided, each of which is selected by a pair of selection switches 4 and 5. Which encryption means is selected is selected based on the selection number 18 supplied to the terminal 6.

FIG. 2 shows an example of the encryption means 3A, and a terminal 21 is supplied with an encryption key of 1.

The encryption key 1 is a key code freely selected by the operator.

This encryption key 1 is replaced, ie, encrypted, in the encryption circuit 22. The encrypted encryption key Ke is roughly supplied to the encryption circuit 23, so that the image signal supplied to the terminal 24 is converted into a predetermined cipher corresponding to this encryption key Ke based on this encryption key Ke. processing will be performed.

In order to ensure its confidentiality, the information signal encrypted by the encryption circuit 23 is supplied to the subsequent encryption circuit 25, where it is roughly encrypted using the second encryption key added here. Processing is performed.

In the embodiment, an adder 26 is provided, in which 3 is added to the third encryption key. The encryption process ends by adding 3 to the third encryption key.

Here, the second and third encryption keys are 2. 3 is fixed.

Therefore, since not only the information (8) but also the encryption key 1 itself is encrypted and multiple stages of encryption processing are performed, the confidentiality of the - layer can be maintained.

The encryption strength differs depending on how the information signal is encrypted.

For example, in the case of an encryption process in which data is replaced and rearranged as opposed to encryption that only involves replacing data, the latter has stronger encryption strength than the former.

Since the encryption strength varies depending on the encryption circuit 22, the contents of the encryption circuits 22 and 23 differ depending on the encryption means 3A to 3C.

The encrypted information signal having a predetermined cryptographic strength can be decrypted by being successfully received, and an example of the decrypting means 30A is shown in FIG.

The information signal input to the terminal 31, that is, the ciphertext, is added with 3 to the third encryption key in the adder 32, and is supplied to the decryption circuit 33 in this state, thereby receiving the second encryption key added to it. An initial decryption process is performed based on key 2.

Then, the encryption key Ke is fully supplied to the final stage decryption circuit 34, and the information signal is finally decrypted by this encryption key Ke.

Note that this decryption means 30A side is also provided with a decryption circuit 35 that encrypts the first encryption key with 1 as Ke.

FIG. 4 shows a system in which the encryption strength of a single encryption means 3A is varied, thereby achieving the same function as using a plurality of encryption means.

Therefore, in the encryption device 3, a suitable means among the encryption means shown in FIG. 1, for example, the encryption means 3A, is used, and this is selected by the selection switch 4.5.

The encryption means 3A is provided with a changing means 11 for changing the encryption strength. In this example, by changing the number of digits of 1 in the first encryption key, a function similar to that of changing the encryption strength is provided.

That is, as shown in FIG. 5, the encryption key 1 is set to have a plurality of encryption strengths, in this example three levels of encryption strength.

In other words, in the case of level 1, 1 is Kl for the encryption key.
In the case of level 2, the sum of the encryption key Kll and 12 is used.

At level 3, encryption keys Kll and 13 are used in addition to 12, and different encryption processes are performed based on the difference in the number of digits.

The number of digits to select for the encryption key is determined by terminal 12.
varies depending on the selection signal supplied to the

Normally, the greater the number of digits in an encryption key, the stronger the encryption, so they are used when a higher level of confidentiality is required.

For example, level 1 is internally confidential, level 2 is internally confidential, and level 3 is top secret. Different, necessary and sufficient confidentiality can be obtained.

In this way, when it is possible to select one content for the encryption key, it becomes possible to provide confidentiality for each group. That is, grouping of information signals to be transmitted can be achieved.

For example, as shown in Figure 6, the group is divided into three stages.
Assuming that Group A is the most confidential, Group B is internally confidential, Group C is internally confidential, and so on, level 3 is required to transmit top secret documents.
1 should be selected as the encryption key. By doing this, confidential documents can only be exchanged within group A.

On the other hand, if level 2 is selected as the encryption key 1, signals can be transmitted between groups A, and signals can also be transmitted between groups B. It also becomes possible to transmit information through group communication. However, information cannot be communicated with Group C.

However, if 1 is selected as the encryption key for level 1, information can be transmitted between these three groups, and communication can be performed by group according to confidentiality. Further confidentiality can be maintained.

In order to realize such grouping, means for forming and decrypting encryption keys must be provided corresponding to each group.

As a result, as shown in Figure 6, the receiving terminal side automatically recognizes which level of encryption key it can receive for each group, and the receiving terminal side automatically recognizes which level of encryption key it can receive for each group. For the terminal, the transmitted information signal cannot be decoded, thereby preventing leakage of communication contents.

FIG. 7 roughly shows another example of the present invention, and the embodiment of FIG. 7 is a combination of the embodiment of FIG. 1 and the embodiment of FIG. 4. That is, the encryption device 3 is provided with a plurality of encryption means 3A to 3C having different encryption strengths, and is configured so that the level of the encryption key can be selected for each of them.

With such a configuration, the confidentiality of the information signal to be transmitted can be ensured even more reliably.

[Effects of the Invention] As explained above, in the configuration of the present invention, by specifying the confidentiality of a document on the sending side, it is possible to achieve encryption with a cryptographic strength suitable for the document. .

That is, on the transmitting side, a plurality of encryption means with different cryptographic strengths are provided in order to keep the information signal to be transmitted confidential. This allows them to choose freely.

According to this configuration, it is possible to perform encryption processing according to the confidentiality of the document, so that leakage of the transmitted information signal can be almost certainly avoided.

Therefore, as described above, the transmission apparatus according to the present invention is extremely suitable for application to facsimile machines and the like that require confidentiality of information signals to be transmitted.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of essential parts showing an example of a transmission device according to the present invention, FIG. 2 is a system diagram showing an example of an encryption means, FIG. 3 is a system diagram showing an example of a decryption means, and FIG. Fig. 5 is a system diagram of a transmission device showing another example of the present invention, Fig. 5 is an explanatory diagram of an encryption key, Fig. 6 is an explanatory diagram of communication by group, and Fig. 7 is an overview of the transmission device according to the invention. FIG. 8 is a system diagram showing another example of a conventional transmission device. 2... A/D converter 3... Encryption devices 3A to 3C... Encryption means 7... Modulator 11... Selection means 22.23.25... Encryption circuit 33.34 .35...Decoding circuit patent applicant Konica Co., Ltd.! ! ! 1FIA 31t4 (tu Fig. 2 37\, 4 da and +42 Fig. 3 4A:q 1ρ counterfeit M4 Fig.

Claims (1)

[Claims] (1) A plurality of encryption means having different cryptographic strengths provided to ensure the confidentiality of the information signal to be transmitted, and a selection means for selecting the plurality of encryption means; A transmission device characterized in that the encryption means is selected according to confidentiality.