Facsimile apparatus

Abstract

A facsimile apparatus is provided with changeover means that makes it possible to pass signals through or to bypass a coder, which encrypts transmission information, and a decoder, which decodes encrypted information that has been received. Whether or not a facsimile apparatus belonging to another party has an encrypting / decoding processing function is verified by a pre-procedure signal. If the other party's apparatus possesses an encrypting / decoding processing function, control is performed in such a manner that encrypting / decoding processing is applied solely to an image signal and a training-check signal transmitted before transmission / reception of the image signal, and encrypting / decoding processing is not applied to a procedure signal which accompanies transmission receptiontransmission / reception of the image signal. If the other party's apparatus does not possess an encrypting / decoding processing function, it is possible to select between terminating communication and performing facsimile communication without executing encrypting / decoding processing.

Description

[0001]This application is a reissue of U.S. Pat. No. 5,509,072, which issued from application Ser. No. 08 / 419,259, which is a division of application Ser. No. 08 / 137,227 filed Oct. 18, 1993, now U.S. Pat. No. 5,430,800, which is a continuation of application Ser. No. 07 / 652,060 filed Feb. 7, 1991, now abandoned.BACKGROUND OF THE INVENTION[0002]This invention relates to a facsimile apparatus capable of subjecting facsimile communication information to cryptographic processing.[0003]Conventional facsimile communication is carried out by a transmission control procedure in accordance with CCITT advisory T.30, and a major characteristic thereof is that a facsimile apparatus is capable of communicating with an unspecified large number of other facsimile apparatus via a public telephone transmission network.[0004]For specific users, such as governmental offices and banks, it is required that the contents or facsimile communications be kept confidential because orof the nature of the work ...

AI Technical Summary

Benefits of technology

[0018]Accordingly, an object of the present invention is to provide a facsimile apparatus in which transmission of an encrypted signal to a receiving facsimile apparatus not equipped with an encryption function is prevented, thereby preventing erroneous operation of the receiving facsimile apparatus and transmission of an encrypted signal to an individual on a telephone by incorrect dialing.

[0019]Another object of the present invention is to provide a facsimile apparatus in which it is possible to determine why a communication ended in an error, even with regard to a telephone call made by incorrect dialing.

[0020]A further object of the present invention is to provide a facsimile apparatus in which additional time required by encrypting of procedure signals can be eliminated, thereby making it possible to rapidly determine whether communication is possible.

[0024]In the arrangement described above, encryption processing is not applied to procedure signals, and only a training-check signal and image signal are encrypted. As a result, additional time required by encrypting of procedure signals can be eliminated, thereby making it possible to determine more rapidly whether communication is possible. In addition, by preventing transmission of an encrypted signal to a facsimile apparatus not possessing an encryption function, erroneous operation of the receiving facsimile apparatus can be avoided and transmission of an encrypted signal to a speaker on a telephone by incorrect dialing can be prevented.

Problems solved by technology

(1) In a case where a call is established between the facsimile apparatus and one to which an encrypting device is not connected, one of the apparatus is entirely incapable of understanding the contents of a communication, the communication cannot be performed normally and operation ends in an error, regardless of whether the operation is transmission or reception. Moreover, when such a situation arises, the operator cannot tell why the operation ended in an error.

(2) In order to perform communication with a facsimile apparatus to which an encrypting device is not connected, the operator must search for another facsimile apparatus not having an encrypting device connected thereto or must open the cover of the original facsimile apparatus, detach the cable of the encrypting device and connect a bypass cable in its place. This is a very troublesome operation, especially when it must be repeated often.

(3) Since all control signals are also encrypted, encrypting of procedure signals takes extrasextra time, and therefore an exorbitant amount of time is needed to determine whether communication is possible with another party's facsimile apparatus.

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