Abstract:
The invention relates to a device for protecting data transmitted by a facsimile machine and provides for encrypting and decrypting of data converted to a binary code. The device is detachably connectable to a facsimile machine for receiving the data and for encrypting/decrypting the data in accordance with a pre-selected key. The encrypted data is stored by the device for subsequent retrieval upon demand. A keypad and an associated visual display allow programming of the electronic function of the device.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to communications equipment, and more particularly to a device for use with facsimile machines and/or computers to allow protected transmission and receipt of confidential messages. 
     The problem of ensuring confidentiality of facsimile transmissions has long been recognized in the communications industry. It is well known that facsimile transmissions can be received by non-designated addressee, and that confidentiality of the transmission can be easily compromised. To overcome this problem, various devices have been proposed for encoding an outgoing message, so that only a designated facsimile machine equipped with the key for decoding the message can decrypt the message into a readable form. Some of these devices can be found in, for example, U.S. Patent Nos.: 
     
       
         
               
               
             
           
               
                   
               
               
                 U.S. PATENT NO. 
                 ISSUE DATE 
               
               
                   
               
             
             
               
                 3,715,478 
                 February 6, 1973 
               
               
                 4,091,423 
                 May 23, 1978 
               
               
                 4,989,244 
                 January 29, 1991 
               
               
                 5,241,595 
                 August 31, 1993 
               
               
                 5,321,749 
                 June 14, 1994 
               
               
                 5,351,136 
                 September 27, 1994 
               
               
                   
               
             
          
         
       
     
     Additionally, a number of devices have been patented for encoding textual data with the use of a computer. Some of these devices are disclosed in U.S. Patent Nos. 
     
       
         
               
               
             
           
               
                   
               
               
                 U.S. PATENT NO. 
                 ISSUE DATE 
               
               
                   
               
             
             
               
                 5,159,635 
                 October 27, 1992 
               
               
                 5,245,655 
                 September 14, 1993 
               
               
                   
               
             
          
         
       
     
     Standard facsimile machines use optical scanners for reading the message to be transmitted, with the image then being changed into a binary code, and then encoded into a dual tone modulated frequency (DTMF) signal suitable for facsimile transmission. The receiving facsimile machine converts the DTMF signal into a binary code, which is then decoded to receive the textual or graphic image transmitted by the first facsimile machine. 
     Many of the known devices utilize decoding electronic means which are built into the facsimile machine and which can be activated by the user with the use of a keyboard or a computer. 
     Some of these devices also have means for storing the encoded information which can be retrieved by a user who possesses the password or a decoder. 
     However, none of the known devices discloses a portable device which can be easily connected to a standard facsimile machine to receive the intended message and to store the information until the user is ready to read it through a facsimile machine or a computer. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to provide a portable device for storing and transmitting an encoded message. 
     It is another object of the present invention to provide a device for encoding facsimile messages at the time when the textual or graphic image is changed into a binary code. 
     It is a further object of the present invention to provide a device for storing facsimile messages which can be connected to a computer or standard facsimile machine for printing of decoded messages. 
     These and other objects of the present invention are achieved through a provision of a device for protecting data transmitted by a facsimile machine. The device comprises a lightweight detachable portable housing which can be attached to a free standing facsimile machine or directly to a telephone line. Mounted within the housing is a keypad and a visual display associated with the keypad for transmitting command signals to an electronic circuitry mounted within the housing. 
     The electronic circuitry allows to encrypt the data received by the facsimile machine and to store the encrypted data for the subsequent retrieval upon demand of the user. When the retrieval signal is transmitted to the electronic circuitry, the data is either transmitted in an encrypted form to a receiving facsimile machine, where it is decrypted in accordance with the matching code, or is decrypted by a similar device which is attached to a remote facsimile machine. The encrypting and decrypting of the data is accomplished at the level of converting the data to a binary code. 
     An optional encoder/decoder of dual tone modulated frequency signal is provided if the device is to be connected to a telephone line or to a computer equipped with input/output ports. The device is equipped with an independent power source to allow functioning of the device independently of a facsimile machine or a computer. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Reference will now be made to the drawings, wherein like parts are designated by like numerals, and wherein: FIG. 1 is a schematic view of the first embodiment of the device in accordance with the present invention. 
     FIG. 2 is a schematic view illustrating a keypad for use with the device of the present invention. 
     FIG. 3 is a schematic illustration of operation of the device in accordance with the present invention connected between the phone line and a facsimile machine. 
     FIG. 4 is a schematic view of a second embodiment of the device in accordance with the present invention suitable for direct attachment to an existing facsimile machine through an input/output port. 
     FIG. 5 is a schematic view of a third embodiment of the device in accordance with the present invention adapted for direct attachment to an existing facsimile machine through an input/output port and adapted for performing encryption and decryption functions. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning now to the drawings in more detail, numeral  10  designates the electrical circuitry utilized in the device in accordance with the present invention. As can be seen in FIG. 1, the electrical circuitry comprises a power supply  12  and a battery  14  to allow the device to receive and store information independently from a source of AC power. The device comprises at least one memory chip  16  which is adapted to store the received information, a DTMF encoder/decoder  18  for encrypting and decrypting of data transmitted by a facsimile machine. The electronic portion of the device in accordance with the present invention can also include an optional clock chip  19  to allow time identification of received/transmitted messages. Suitable function chip  20  and program chip  22  allow to perform the necessary operations and mathematical functions with the use of keypad  30  shown in FIG.  2 . 
     The device is also provided with suitable means  24  to allow connecting of the device to a computer or facsimile machine, such as an input/output port for connection to a computer or a facsimile machine. “In” and “out” phone lines  26  and  28  respectively, are provided to receive and transmit the data via phone lines. 
     Turning now to FIG. 2, the keypad which allows the user to transmit instructional signals to the electronic circuit  10  is illustrated. The keypad is conveniently provided with a number of functional keys, such as “recall”, “send”, “print”, “delete”, and “enter.” These functional keys are used in cooperation with numerical keys designated by numeral  32  in the drawings. The keypad permits the user to input various instructions for the operation of the device and for inputting the key code used for encrypting and decrypting of messages. 
     A video display window  34  allows the user to visually monitor the functions selected with the use of the keypad  30 . The window  34  can be a standard LED display. 
     FIG. 3 illustrates, in a schematic form, the function of the device in accordance with the present invention. The user inputs his instructions on a keypad  30  and transmits instructions to the program chip  22 . The program means  22  transmits the signal to the means for encrypting and decrypting messages which is made in the form of a function chip  20 . If the message is to be transmitted immediately, the signal is passed (chip to chip) to the DTMF encoder/decoder means  18  and then to a phone line  36 . Alternatively, the message from the encoding/decoding means can be transmitted to a facsimile machine to be read through a line  38 . 
     If the user desires to retain the message in the memory of the device, the signal is forwarded to the data storage means  16  for storing the information in the memory chip instead of being forwarded immediately to the encoder/decoder means  18 . In accordance with the present invention, a mathematical algorithm based on Boulean algebraic x/or function is used to encrypt the binary code by changing the binary code in accordance with a predetermined key code. 
     The new binary code in its encrypted form is then changed into a DTMF signal and transmitted through the phone line  36  or through the fax line  38  to the addressee. At the receiving end, the DTMF signal is decoded to retrieve the encrypted binary code which is then decrypted using the matching key code to allow printing of the message in a readable form. Unless the addressee of the message uses a matching key code, the massage is printed in a scrambled form unsuitable for reading. 
     As part of the encryption process, a marker is inserted into the usual stream of the fax transmission to identify this particular message as encrypted. Once the device identifies the incoming facsimile message as encrypted, it scans for the key code. If this code has been entered by the addressee, the received message is decrypted and printed in the usual manner. 
     However, if the key code has not been entered, the message is stored in memory until the addressee enters the key code and instructs the device to decrypt and print the facsimile message. The device of the present invention can also be used for storing non-encoded facsimile messages until such time as the user is ready to recall and print the message. 
     FIG. 4 illustrates a second embodiment of the device in accordance with the present invention designated by numeral  40  in the drawings. The device  40  is adapted for direct attachment to an existing facsimile machine through a built-in input/output port  42  or through an internal buss in a facsimile machine or computer. The battery and the power supply are illustrated at  71 , FIG. 5 in the embodiment. The device  40 , similarly to the device  10  provides for the use of an instruction input keypad  44 , which is used for directing the programs of the device  40  through a programming means  46 . The instructions can direct an encrypting/decrypting means  48  to immediately encrypt or decrypt the transmitted message or, in the alternative, to store the information in the data storage means  50 . The DTMF chip is omitted here, since it is part of a standard facsimile machine. 
     The device shown in FIG. 4 can be used for retrofitting existing facsimile machines supplied with input/output ports to provide encryption and decryption functions to the existing machine. The incoming facsimile message can be stored in the data storage means  50  until the user is ready to retrieve the message and has introduced the matching key code to allow decryption. 
     The device  40  has direct access to the binary code of a standard facsimile machine and can function without DTMF encoder/decoder chips. The binary code produced by the facsimile machine is immediately encrypted for outgoing messages before being converted to a DTMF signal or decrypted from incoming facsimile messages after being converted from the incoming DTMF signal. 
     Turning now to FIG. 5, a third embodiment of the device in accordance with the present invention is shown in its schematic form. The device  60  is provided with a means for programming the messages  62 , means for encrypting/decrypting messages  64  and means for storing information  66 . A clock  68  can be optionally provided for identifying the time of the transmission or reception. 
     The device  60 , similar to the first embodiment  10  and the second embodiment  40  is provided with an input/output port  70 . The third embodiment can be also used for direct attachment to a computer or an existing facsimile machine. The key board can be the same as that used for the first embodiment of the present invention. 
     All of the embodiments contain means for storing data and encrypting/decrypting messages. The received information can be stored until a device is connected to a suitable printing means, such as a computer or a standard facsimile machine. The incoming facsimile message can be stored encrypted until the recipient inputs the code allowing decryption of the message. It is one of the advantages of the present invention that the device can be connected to a phone line to receive facsimile messages without attachment to a receiving facsimile machine. The incoming fax message can be stored encrypted or decrypted, as the user selects, until such time as the user is ready to print the message. 
     Similarly, an outgoing facsimile message can be stored in the device and be transmitted, or encrypted and transmitted at a later time. The device can be attached to a standard facsimile machine since the data storage means allow to retain the information for an indefinite period of time. The device of the present invention can be detached and transported whenever the user desires and then reattached to a telephone line for transmission of the messages or for reception. 
     It is preferred that the device of the present invention be made lightweight to allow its ready portability. As will be appreciated, by those skilled in the art, the device of the present invention can be made a part of a standard facsimile machine with minor necessary amendments. In that case, the encryption and decryption of messages will be performed by the same facsimile machine that transmits or receives messages. The device may comprise a light weight detachable portable housing or insertable input/output card. 
     Many changes and modifications can be made in the design of the present invention without departing from the spirit thereof. I, therefore, pray that my rights to the present invention be limited only by the scope of the appended claims.