JP2008048050A - Encrypted data communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reproduce the received video image/sound without deteriorating them when video image/sound streams encrypted by different keys are changed and received. <P>SOLUTION: Data streams are encrypted by network cameras 1 and 2 by the use of different encryption keys; and furthermore the MAC address or IP address of the network cameras 1 and 2 is added to the user data region of each decryption unit of the data stream, and is transmitted as the encrypted streams to a terminal device 8 through a network NW. The terminal device 8 receives the encrypted streams arriving through the network NW, a decryptor 16 acquires a decryption key corresponding to the MAC address or IP address acquired from the user data region of the received encrypted streams, from a decryption key table 7. The decryptor 16 decrypts the encrypted streams by the decryption unit using the acquired decryption key, and supplies the decrypted streams to a decoding part 17. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an encrypted data communication system in which, for example, a data stream captured by a network camera or the like is encrypted and transmitted to a terminal device.

  In recent years, video is digitally encoded (compressed) to generate a video stream, which is actively distributed from a server device to a receiving device.

  In addition, when distributing a video stream, a method of encrypting a non-header portion of the video stream is conceivable as a method of distributing video only to a limited number of receiving devices. In this method, a correct video can be reproduced by a receiving device having an encryption key, but only a video having a deteriorated image quality can be obtained by a terminal device having no encryption key.

Note that a technique has been proposed in which image information is secured by transmitting encrypted data obtained by changing the reading order of image data in a transmission device (see, for example, Patent Document 1).
JP 2003-125326 A

  By the way, when the transmission device encrypts the video and distributes the encrypted video to the communication network, and the reception device decrypts and reproduces the encrypted video, the transmission device needs to have an encryption key and the reception device has a decryption key. There is.

  However, when a plurality of transmission devices encrypt and transmit a video / audio stream using mutually different encryption keys, when the connection destination transmission device is switched in the reception device, the buffer of the reception device is not Data encrypted by the transmission apparatus and data encrypted by the transmission apparatus after switching are mixed. For this reason, for example, if the decryption key is changed according to the IP address at the time of switching the connection destination, the data encrypted by the transmission device before switching stored in the buffer cannot be correctly decrypted, and thus the reproduced video and audio deteriorate. There is a problem.

  The present invention has been made paying attention to the above circumstances, and its purpose is to deteriorate received video / audio even when video / audio streams encrypted with different keys are switched and received. It is an object of the present invention to provide an encrypted data communication system that can be reproduced without any problems.

  To achieve the above object, the present invention relates to a plurality of transmission devices that encrypt and transmit data streams using mutually different encryption keys, the plurality of transmission devices connected via a communication network, and the plurality of transmissions. An encrypted data communication system comprising: a receiving device that receives an encrypted data stream transmitted from a device, wherein the transmitting device encrypts the data stream using the encryption key; Means for adding unique information assigned to the transmission device for each decryption unit of the encrypted data stream, and the encrypted data stream with the unique information added to the receiving device via the communication network Means for transmitting to the receiving device, wherein the receiving device uses a decryption key paired with an encryption key used by the plurality of transmitting devices. Means for storing the information in association with the assigned unique information; means for switching and receiving the encrypted data streams transmitted from the plurality of transmitting devices; and reading the unique information from the received encrypted data streams And a means for obtaining a decryption key corresponding to the read unique information from the storage means, and decrypting the encrypted data stream in a decryption unit using the obtained decryption key. To do.

  In the above configuration, the transmission apparatus adds the unique information of the transmission apparatus to a user data area or the like provided for each decryption unit of the encrypted data stream and transmits the data. The receiving device stores the decryption key paired with the encryption key in advance in association with the unique information of the transmitting device, and uses the decryption key corresponding to the unique information included in the received encrypted data stream to encrypt the encrypted data stream Are decoded in units of decoding. With this configuration, even when a network camera that outputs a video / audio data stream or the like encrypted with different encryption keys is switched, the video or audio encrypted using the decryption key corresponding to the unique information is switched. Since the stream is decoded in units of decoding, it is possible to reproduce the video / audio without degrading.

The present invention is characterized by having the following various configurations.
In the first configuration, the means for adding the unique information detects an area to which the unique information is added for each decryption unit of the encrypted data stream, and when the area to which the unique information is added is detected, The unique information assigned to the transmission device is inserted into the detected area, and if the area to which the unique information is added is not detected, an area to which the unique information is added is generated for each decoding unit, and the generation Means for inserting the unique information into the generated area and reading the unique information, wherein the means for reading the unique information further deletes the area after reading the unique information from the generated area. To do. With this configuration, for example, the present invention can be applied to a data stream in which no user data area exists.

  The second configuration is characterized in that either one of an IP address and a MAC (Media Access Control) address assigned to each transmission device is used as the unique information. The configuration can be facilitated by using a value assigned in advance such as an IP address or a MAC address.

  Therefore, according to the present invention, there is provided an encrypted data communication system capable of reproducing a received video / audio without degrading it even when video / audio streams encrypted with different keys are switched and received. be able to.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing an embodiment of an encrypted data communication system according to the present invention. This encrypted data communication system includes network cameras 1 and 2, a network NW, and a terminal device. The network cameras 1 and 2 and the terminal device are respectively connected to the network NW and can communicate with each other via the network NW.

  The network cameras 1 and 2 serving as transmission devices encrypt the video streams with mutually different encryption keys, add unique information for each decryption unit, and output to the network NW. Details will be described later. The terminal device is composed of, for example, a personal computer (hereinafter referred to as client personal computer 3) that functions as a client. The client PC 3 stores a decryption key corresponding to the encryption key used in the network cameras 1 and 2, and the network camera 1 uses the decryption key corresponding to the network cameras 1 and 2 that distribute the video stream. , 2, the video and audio can be viewed by decrypting the encrypted stream received from.

  The terminal device may be the browsing terminal 4 that functions as a client, for example. The browsing terminal 4 stores a decryption key corresponding to the encryption key used in the network camera 1, and uses this decryption key to decrypt the encrypted stream received from the network camera 1 and monitor the video 5 Thus, the audio can be viewed through the speaker 6.

FIG. 2 is a block diagram showing a configuration of a terminal device used in the encrypted data communication system of the present invention.
The terminal device 8 includes a decryption key table 7, a communication unit 11, a buffer 12, a determination unit 13, switches 14 and 15, a decryption unit 16, and a decode unit 17. The network camera 1 includes a key 1 and the network camera 2 includes a key 2. The video camera / audio stream is encrypted using different encryption keys and transmitted to the terminal device 8 via the network NW. The decryption key table 7 stores decryption keys in association with the MAC address or IP address assigned to the network board mounted on each network camera.

  The communication unit 11 stores the encrypted video / audio stream distributed from the network camera 1 or 2 in the buffer 12. Here, it is assumed that the terminal device 8 switches the connection destination from the network camera 1 to the network camera 2. At this time, the buffer 12 stores both the video / audio stream 18 encrypted by the network camera 1 using the key 1 and the video / audio stream 19 encrypted by the network camera 2 using the key 2. It will be in a state to be.

  The determination unit 13 reads the video / audio stream stored in the buffer 12 and switches the switch 14 and the switch 15 according to the read video / audio stream. If the read data is an encrypted part, the determination unit 13 switches the switch 14 so that the data is output to the decryption unit 16. The decryption unit 16 obtains a decryption key corresponding to the input data with reference to the decryption key table 7, and decrypts the encrypted data in decryption units using the obtained decryption key. The decoding unit here refers to, for example, a VOH unit for an MPEG-4 stream, a frame unit for a JPEG stream, and a packet unit for an audio stream. In addition, when there is no decryption key corresponding to the decryption key table 7, the determination unit 13 continues to discard the stream until the next VOH header is found in the case of an MPEG-4 stream, and examines the next VOH header. If it is a stream, the next frame is examined. If it is an audio stream, the next packet is examined.

  On the other hand, when the read data is an unencrypted part, the determination unit 13 switches the switch 14 and the switch 15 and outputs the input data to the decoding unit 17 as it is. The decoding unit 17 decompresses the decoded video / audio stream output from the switch 15.

Here, the data structure of the video / audio stream used in the encrypted data communication system configured as described above will be described.
(For MPEG-4 stream)
FIG. 3 is a diagram showing a data structure of an MPEG-4 stream transmitted in the encrypted data communication system. FIG. 3A shows the original MPEG-4 stream before encryption. As shown in FIG. 3B, the network cameras 1 and 2 which are transmission side devices encrypt the MPEG-4 stream in units of VOPs. Further, as shown in FIG. 3C, the network cameras 1 and 2 add the MAC address or IP address assigned to the network interface to the user data area of the MPEG-4 stream and output it to the network NW.

  FIG. 4 is a diagram showing the data structure of an MPEG-4 stream received by this system. FIG. 4A shows an MPEG-4 stream received by the terminal device 8. The terminal device 8 first acquires the MAC address or IP address stored in the user data area of the MPEG-4 stream. Then, the decryption key corresponding to the MAC address or IP address is read with reference to the decryption key table 7. The terminal device 8 uses the read decryption key to decrypt the encrypted VOP data as shown in FIG. As described above, when the decryption key corresponding to the MAC address or the IP address does not exist in the decryption key table 7, the decryption unit 16 does not perform the decryption process, and the determination unit 13 discards the stream until the VOH header is detected. Subsequently, the decoding unit 16 checks the next VOH header (not shown). If there is a decryption key corresponding to the MAC address or IP address, the encrypted VOP data is decrypted one after another using the read decryption key as shown in FIG.

(JPEG stream)
FIG. 5 is a diagram showing a data structure of a JPEG stream transmitted by the encrypted data communication system. FIG. 5A shows an original JPEG stream before encryption. As shown in FIG. 5B, the network cameras 1 and 2 insert an APP marker partial sequence into the original JPEG stream. Next, as shown in FIG. 5C, the JPEG encoded data is encrypted. Further, as shown in FIG. 5 (d), the MAC address or IP address assigned to the network interface is added to the APP marker subsequence of the JPEG stream, and the result is output to the network to the NW.

  FIG. 6 is a diagram showing the data structure of a JPEG stream received by this system. FIG. 6A shows a JPEG stream received by the terminal device 8. First, the terminal device 8 acquires the MAC address or IP address stored in the APP marker subsequence of the JPEG stream. Then, the decryption key corresponding to the acquired MAC address or IP address is read from the decryption key table 7. The terminal device 8 uses the read decryption key to decrypt the encrypted JPEG encoded data as shown in FIG. 6B. As described above, when the decryption key corresponding to the MAC address or the IP address does not exist in the decryption key table 7, the decryption unit 16 does not perform the decryption process, and the decryption unit 16 stores the APP marker partial sequence of the next frame. Check (not shown).

(For audio stream)
FIG. 7 is a diagram showing a data structure of an audio stream transmitted in this encrypted data communication system. FIG. 7A shows an original audio stream before encryption. As shown in FIG. 7B, the network cameras 1 and 2 encrypt the original audio stream. Next, as shown in FIG. 7C, a synchronization marker and a user data area are added before the encrypted audio stream. Then, as shown in FIG. 7 (d), the MAC address or IP address assigned to the network interface is added to the user data area of the audio stream and output to the network NW. The terminal device 8 can correctly extract the audio stream by detecting the synchronization marker from the plurality of audio streams stored in the buffer 12.

  FIG. 8 is a diagram showing a data structure of an audio stream received by this system. FIG. 8A shows an audio stream received by the terminal device 8. First, the terminal device 8 acquires the MAC address or IP address stored in the user data area of the audio stream. Then, the decryption key corresponding to the acquired MAC address or IP address is read from the decryption key table 7. The terminal device 8 uses the read decryption key to decrypt the encrypted speech encoded data as shown in FIG. 8B, and further, the synchronization marker and the user as shown in FIG. 8C. Delete data area and extract audio data. As described above, when the decryption key corresponding to the MAC address or the IP address does not exist in the decryption key table 7, the decryption unit 16 does not perform the decryption process, and the decryption unit 16 examines the next received audio stream (see FIG. Not shown).

Next, the operation of the encrypted data communication system configured as described above will be described for each data stream format.
(MPEG-4 transmission processing)
FIG. 9 is a flowchart showing the procedure and contents of MPEG-4 stream transmission processing in the network cameras 1 and 2. The variable a is a state variable, and the operation is switched according to this value.

  In step S9a in FIG. 9, the state variable a is initialized to 0 at the start of transmission processing, and start code detection processing is performed on the MPEG-4 stream (step S9b). In step S9c, when a VOH header is detected from the MPEG-4 stream as shown in FIG. 3A, the process proceeds to step S9d, and the value of the state variable a is checked. Here, since a = 0, the process proceeds to step S9e to set the value of a to 1, and then in step S9b, the start code detection process is performed again on the MPEG-4 stream.

  Next, in step S9h, when the VOP header is detected from the MPEG-4 stream (the first VOP header is detected), the value of the state variable a is checked (step S9i). Here, since a = 1, the process proceeds to step S91 and the value of a is set to 2. Then, in step S9b, the start code detection process is performed again on the MPEG-4 stream. In this embodiment, since it is assumed that VOP data between VOP headers is encrypted, encryption is not performed when the first VOP header is detected.

  In step S9h, when the VOP header is detected from the MPEG-4 stream (second and subsequent VOP headers are detected), the value of the state variable a is checked in step S9i. Here, since a = 2, the VOP data is encrypted as shown in FIG. 3B (step S9j). Then, an MPEG-4 stream including “VOH header to encrypted VOP data” including the encrypted data is output to the network (step S9k). Thereafter, the process returns to step S9b again to perform start code detection processing for the MPEG-4 stream.

  Subsequently, when a VOP header is detected from the MPEG-4 stream in step S9h, the value of the state variable a is checked in step S9i. Since a = 2 in this case, the VOP data is encrypted (step S9j). Then, “VOP header + encrypted VOP data” including this encrypted data is output to the network (step S9k). Thereafter, the above process is repeated until the next VOH header is detected.

  In step S9c, when the VOH header is detected from the MPEG-4 stream, the value of the state variable a is checked (step S9d). Here, since a = 2, the VOP data is encrypted in step S9f, and “VOP header + encrypted VOP data” including this encrypted data is output to the network (step S9g). Thereafter, the state variable a is set to 1 in step S9e, and the process proceeds to step S9b again to perform start code detection processing for the MPEG-4 stream.

(Receiving processing of MPEG-4 stream)
FIG. 10 is a flowchart showing the procedure and contents of the reception process of the encrypted MPEG-4 stream in the terminal device 8. The variable a is a state variable, and the operation is switched according to this value.

  First, in step S10a, the terminal device 8 initializes the state variable a to 0, and performs start code detection processing on the encrypted MPEG-4 stream (step S10b).

  In step S10c, when the VOH header is detected from the encrypted MPEG-4 stream as shown in FIG. 4A, the value of the state variable a is checked (step S10d). Here, since a = 0, the process proceeds to step S10e, where the MAC address or IP address stored in the user data area of the MPEG-4 stream is obtained, and the decryption key corresponding to the MAC address or IP address is decrypted. Search from the key table 7. If there is a decryption key corresponding to the MAC address or IP address in step S10f, the state variable a is set to 1 in step S10g, and then the process proceeds to step S10b again for the start code of the encrypted MPEG-4 stream. Perform detection processing.

  Next, in step S10j, when a VOP header is detected from the encrypted MPEG-4 stream (the first VOP header is detected), the value of the state variable a is checked in step S10k. Here, since a = 1, this value is set to 2 in step S101, and then the process proceeds to step S10b again to perform start code detection processing for the encrypted MPEG-4 stream.

  Next, when a VOP header is detected from the encrypted MPEG-4 stream in step S10j (second and subsequent VOP headers are detected), the value of state variable a is checked in step S10k. Here, since a = 2, the process proceeds to step S10m, and as shown in FIG. 4B, the decryption unit 16 uses the decryption key corresponding to the MAC address or the IP address to encrypt the VOP. Decrypt the data. Then, the MPEG-4 stream from the VOH header to the VOP data is sent to the decoding unit 17, and the process proceeds to step S10b again to perform start code detection processing for the encrypted MPEG-4 stream.

  Subsequently, in step S10j, when a VOP header is detected from the encrypted MPEG-4 stream, the value of the state variable a is checked in step S10k. Here, since a = 2, the process proceeds to step S10m, and the decryption unit 16 decrypts the VOP data encrypted using the key corresponding to the MAC address or IP address. Then, (VOP header + VOP data) is supplied to the decoding unit 17. Thereafter, the above process is repeated until the next VOH header is detected.

  When a VOH header is detected from the encrypted MPEG-4 stream in step S10d, the value of the state variable a is checked (step S10e). Here, since a = 2, the process proceeds to step S <b> 10 h, and the decryption unit 16 decrypts the encrypted VOP data and supplies this (VOP header + VOP data) to the decode unit 17. Thereafter, the process proceeds to step S10g, the state variable a is set to 1, and the process proceeds to step S10b again to perform start code detection processing for the encrypted MPEG-4 stream. Thereafter, this process is repeated.

(JPEG stream transmission processing)
FIG. 11 is a flowchart showing the JPEG stream transmission processing procedure and contents in the network cameras 1 and 2.
First, in step S11a, a start code detection process is performed on the JPEG stream.

  When an SOI (Start of Image) marker is detected from the JPEG stream as shown in FIG. 5A in step S11b, the process proceeds to step S11c, and the APP marker portion is added to the JPEG stream as shown in FIG. 5B. Insert a column. Then, in step S11d, the JPEG encoded data is encrypted as shown in FIG. 5C, and in step S11e, the MAC address or IP address is added to the APP marker partial sequence, so that FIG. An encrypted JPEG stream as shown in FIG. Thereafter, the above process is repeated.

(JPEG stream reception processing)
FIG. 12 is a flowchart showing the procedure of the reception process of the encrypted JPEG stream in the terminal device 8 and its contents.
First, start code detection processing is performed on the encrypted JPEG stream (step S12a). In step S12b, when an SOI marker is detected from the encrypted JPEG stream as shown in FIG. 6A, the process proceeds to step S12c, where the MAC address or IP address stored in the APP marker subsequence is acquired, With reference to the decryption key table 7, a decryption key corresponding to the acquired MAC address or IP address is searched. In step S12d, when there is a decryption key corresponding to the MAC address or IP address, the decryption unit 16 proceeds to step S12e, decrypts the encrypted JPEG encoded data, and supplies the decrypted JPEG encoded data to the decode unit 17. The decoding unit 17 decompresses the decoded JPEG encoded data supplied from the switch 15 (step S12f).

  On the other hand, in the determination in step S12b, the determination unit 13 switches the switches 14 and 15 and discards the data until an SOI marker is detected. Also, in the determination in step S12d, even when there is no decryption key corresponding to the MAC address or the IP address, the determination unit 13 switches the switches 14 and 15 to discard the data. Thereafter, the above process is repeated.

(Audio stream transmission processing)
FIG. 13 is a flowchart showing the procedure of audio stream transmission processing in the network cameras 1 and 2 and the contents thereof.
In step 13a, the audio data is encrypted as shown in FIG. 5B, and then in step S13b, a synchronization marker and a user data area are added before the encrypted audio data. In step S13c, the MAC addresses or IP addresses of the network cameras 1 and 2 are added to the added user data area, and the encrypted audio stream is output to the network NW.

(Audio stream reception processing)
FIG. 14 is a flowchart showing the procedure and contents of the reception process of the encrypted audio stream in the terminal device 8.
First, in step S14a, the terminal device 8 performs a start code detection process on the encrypted audio stream. In step S14b, when the determination unit 13 detects a synchronization marker from the encrypted audio stream as illustrated in FIG. 8A, in step S14c, the determination unit 13 acquires a MAC address or an IP address stored in the user data area. Then, the decryption unit 16 searches the decryption key table 7 for a decryption key corresponding to this MAC address or IP address. If there is a decryption key corresponding to the MAC address or IP address in step S14d, the decryption unit 16 uses the decryption key in step S14e to encrypt the encrypted voice data as shown in FIG. Is decrypted. Further, the determination unit 13 discards the synchronization marker and the user data area by switching the switch 15 and supplies only the decoded audio stream to the decoding unit 17 as shown in FIG. In step S14g, the decoding unit 17 expands the supplied audio stream.

  As described above, in the above embodiment, the network cameras 1 and 2 encrypt the data streams with mutually different encryption keys, and further, the MAC addresses or IP addresses of the network cameras 1 and 2 for each decryption unit of the data stream. After being added to the user data area, it is transmitted as an encrypted stream to the terminal device 8 via the network NW. The terminal device 8 receives the encrypted stream that arrives via the network NW, and the decryption unit 16 decrypts the decryption key corresponding to the MAC address or IP address acquired from the user data area of the received encrypted stream. Obtained from the key table 7. The decryption unit 16 decrypts the encrypted stream in units of decryption using the acquired decryption key, and supplies the decrypted unit 17 with the decryption unit.

  Therefore, according to the above-described embodiment, it is possible to provide an encrypted data communication system capable of reproducing without degrading video and audio even when switched to data encrypted with a different encryption key. .

  The present invention is not limited to the above embodiment. For example, in the above embodiment, three formats of MPEG-4, JPEG, and audio stream have been described as examples of the format of the data stream. However, the present invention can be applied to other formats. Also, the configuration of the encrypted data communication system shown in FIG. 2 and the operation procedure and contents thereof can be variously modified and implemented without departing from the present invention.

  In short, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

1 is a schematic configuration diagram showing an embodiment of an encrypted data communication system according to the present invention. The block diagram which shows the structure of the terminal device used for the encryption data communication system of this invention. The figure which shows the data structure of the MPEG-4 stream transmitted with this system. The figure which shows the data structure of the MPEG-4 stream received with this system. The figure which shows the data structure of the JPEG stream transmitted with this system. The figure which shows the data structure of the JPEG stream received by this system. The figure which shows the data structure of the audio | voice stream transmitted with this system. The figure which shows the data structure of the audio | voice stream received with this system. The flowchart which shows the procedure of the transmission process of MPEG-4 stream, and its content. The flowchart which shows the procedure of the reception process of MPEG-4 stream, and its content. The flowchart which shows the procedure of the transmission process of a JPEG stream, and its content. The flowchart which shows the procedure of the reception process of a JPEG stream, and its content. The flowchart which shows the procedure of the transmission process of an audio | voice stream, and its content. The flowchart which shows the procedure of the reception process of an audio | voice stream, and the content.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 2 ... Network camera, NW ... Network, 3 ... Client computer with key, 4 ... Reading terminal with key, 5 ... Monitor, 6 ... Speaker, 7 ... Decryption key table, 8 ... Terminal device, 11 ... Communication , 12 ... buffer, 13 ... determining unit, 14, 15 ... switch, 16 ... decoding unit, 17 ... decoding unit, 18 ... video / audio stream encrypted with key 1, 19 ... encrypted with key 2 Video / audio stream.

Claims (3)

A plurality of transmitting apparatuses that encrypt and transmit data streams using mutually different encryption keys, and an encrypted data stream that is connected to the plurality of transmitting apparatuses via a communication network and is transmitted from the plurality of transmitting apparatuses. An encrypted data communication system comprising a receiving device for receiving
The transmitter is
Means for encrypting the data stream using the encryption key;
Means for adding unique information assigned to the transmission device for each decryption unit of the encrypted data stream;
Means for transmitting the encrypted data stream, to which the unique information is added, to the receiving device via the communication network;
The receiving device is:
Means for storing a decryption key paired with an encryption key used by the plurality of transmission devices in association with unique information assigned to the transmission device;
Means for switching and receiving encrypted data streams transmitted from the plurality of transmitting devices;
Means for reading the unique information from the received encrypted data stream;
Means for obtaining a decryption key corresponding to the read unique information from the storage means, and means for decrypting the encrypted data stream in decryption units using the obtained decryption key. Data communication system. The means for adding the unique information detects an area to which the unique information is added for each decryption unit of the encrypted data stream, and when an area to which the unique information is added is detected, When the unique information assigned to the transmission apparatus is inserted and the area to which the unique information is added is not detected, an area to which the unique information is added is generated for each decoding unit, and the unique information is generated in the generated area. Insert information,
2. The encrypted data communication system according to claim 1, wherein the means for reading the unique information further deletes the area after reading the unique information from the generated area.   2. The encrypted data communication system according to claim 1, wherein any one of an IP (Internet Protocol) address and a MAC (Media Access Control) address assigned to each of the transmitting devices is used as the unique information.

Images