JP2013048485A - Transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitter, a receiving method, and a receiver capable of transferring data so that the cause of a failure in authentication can be identified, and capable of properly coping with the failure in accordance with the cause of the failure in authentication without giving a user an uneasy feeling on a receiving side.SOLUTION: A stream 1 having a plurality of particular packets 20 inserted into a series of stream packets 10 with an authenticator attached thereto is transmitted and received. Each particular packet 20 includes information indicating the number of stream packets contained between the particular packet 20 and a particular packet 20 adjacent in a prescribed stream direction of the series of stream packets 10. The receiver 100 compares, when authentication is unsuccessful, the number of stream packets contained in the particular packets 20 and the number of actually received stream packets and, from the result of the comparison, identifies whether the failure in authentication is due to alteration or packet loss.

Description

  The present invention relates to a transmitting device that transfers data authentically by a streaming transfer method, a receiving method that receives data transferred from the transmitting device and performs stream authentication, and a receiving device.

  Conventionally, there are two methods for transferring data such as moving images and voices: a method for reproducing data after receiving all the data, and a streaming transfer method for reproducing data each time data is received. In general, when the amount of data to be transferred is large compared to the transmission speed, the latter streaming transfer method is used in consideration of real-time characteristics in data reproduction.

  In the streaming transfer method, it is necessary to authenticate transfer data (message) to ensure safety. As an example of the authentication method, for example, the method shown in FIG. 7 is known. In this authentication method, a message is packetized on the transmission side, a hash value by a hash function H is calculated from the original message as a message authenticator for each packet, and the calculated hash value is added to the original message and transmitted. To do. On the receiving side, a hash value is calculated from the received message, the calculated hash value is compared with the received hash value, and if the two hash values do not match, the message has fraud such as falsification. Since there is a possibility, the fact that the authentication has failed is displayed and the data reproduction is prohibited.

  The authentication method shown in FIG. 7 performs authentication for each packet, so that even if there is a packet loss, authentication can be performed from the next packet. However, in this authentication method, if a malicious attacker decodes the message authenticator generation method and sends a packet with a message authenticator attached to an illegal packet, the receiver side is authenticated successfully. Therefore, there is a problem that an illegal packet cannot be detected and the security of the message cannot be guaranteed.

  As an authentication method for solving this problem, for example, as shown in FIG. 8, on the transmission side, a message authentication code of each packet is calculated using the original message of the packet and the hash value of the previous packet. By doing so, it is conceivable that the hash value of the previous packet is associated with the hash value of the next packet to authenticate the entire packet stream.

  According to the authentication method shown in FIG. 8, since message authenticators are continuously generated from the top packet, it is possible to improve the security of the message. However, in this authentication method, when even one packet loss occurs, the chainability of the packet stream is canceled at that time, so it is impossible to ensure the security of the subsequent packets.

  In this case, as described above, simply displaying that authentication has failed and prohibiting data reproduction, the user can determine whether the cause of authentication failure is packet loss or message tampering. Can not be identified. For this reason, there is a concern about giving the user anxiety that the falsified data has been received, and the user may or may not perform the receiving process again. There is concern that it will be difficult to determine the next action to be taken.

  As an authentication method for solving the authentication failure due to packet loss in the case of FIG. 8, the method shown in FIG. 9 is also known (see, for example, Patent Document 1). In this authentication method, on the transmission side, each packet Pi is newly input with a message hi and a chain hi2 of the hash value two packets before, a chain hi1 of the hash value one packet previous, and hi2 and hi1. It is composed of a hash value Hi and transmitted.

  According to the authentication method shown in FIG. 9, since the message authenticator is chained by the hash value one packet before and the hash value two packets before, the security of the message can be further improved, Even if one packet is lost on the receiving side, message authentication data can be chained, so that it is possible to guarantee the security by authentication for subsequent packets.

  However, since the authentication method shown in FIG. 9 supports only one packet loss, if two or more packet losses occur successively, the authentication fails similarly. Such two or more consecutive packet losses are likely to occur frequently depending on the radio wave condition, particularly when the receiving device is a portable terminal. For this reason, similar to the case of FIG. 7, simply displaying that the authentication has failed and prohibiting data reproduction causes the same problem.

  In order to cope with two or more consecutive packet losses, it may be possible to chain up to three or more previous packet hash values, but in this case, the amount of data in the message authenticator in each packet is large. As a result, the amount of data of the original message to be transmitted is reduced, so there is a concern that the authentication process may take a long time, and the total number of packets for transferring the required data increases and the transfer takes time. Is concerned. In addition, when a packet loss exceeding the allowable number of packets occurs, the same problem as described above occurs.

JP 2001-251296 A

  Therefore, an object of the present invention made in view of such a point is that data can be transferred so that the cause of the authentication failure can be identified, and the receiving side can appropriately respond to the cause of the authentication failure without giving the user anxiety. It is an object of the present invention to provide a transmission device, a reception method, and a reception device that can cope with the problem.

The invention of the transmitter according to claim 1 that achieves the above object is as follows:
A plurality of specific packets are inserted into a series of stream packets to which an authenticator is added, and each specific packet is a stream packet to be used for authentication included between adjacent packets in the predetermined stream direction of the series of stream packets. Stream generation means for generating a stream including information indicating a number;
Transmitting means for transmitting the stream generated by the stream generating means;
It is characterized by providing.

The invention according to claim 2 is the transmission apparatus according to claim 1,
The stream generation means inserts the plurality of specific packets at an arbitrary stream packet interval.

Furthermore, the invention of the receiving method according to claim 3 that achieves the above object is as follows:
It has a plurality of specific packets inserted in a series of stream packets to which an authenticator is added, and is used for authentication included between each specific packet and a specific packet adjacent in the predetermined stream direction of the series of stream packets. A receiving method for receiving a stream generated by including information indicating the number of stream packets to be processed,
Authenticate the received stream packet;
When authentication fails, the number of stream packets to be used for authentication included in the received specific packet and the authentication received between the specific packet and a specific packet adjacent in the predetermined stream direction of the specific packet are used. When the number of stream packets to be used for the received authentication matches the number of stream packets to be used for the authentication included in the specific packet based on the comparison with the number of stream packets to be determined, the stream is regarded as an invalid stream. If the number of stream packets to be used for the received authentication is less than the number of stream packets to be used for the authentication included in the specific packet, it is determined that the packet is lost.
It is characterized by this.

Furthermore, the invention of the receiving device according to claim 4 that achieves the above object is as follows:
It has a plurality of specific packets inserted in a series of stream packets to which an authenticator is added, and is used for authentication included between each specific packet and a specific packet adjacent in the predetermined stream direction of the series of stream packets. Receiving means for receiving a stream generated including information indicating the number of stream packets to be transmitted;
Authentication means for performing stream authentication using the stream packet received by the receiving means;
A counter that counts the number of stream packets to be used for the authentication received by the receiving means between sequential specific packets received by the receiving means;
A comparison means for comparing the number of stream packets to be used for authentication contained in the specific packet received by the receiving means and the value of the counter when the authentication by the authentication means fails;
If the value of the counter matches the number of stream packets to be used for authentication included in the specific packet based on the comparison result by the comparison means, the stream is determined to be an invalid stream, and the value of the counter Is smaller than the number of stream packets to be used for authentication included in the specific packet, a determination unit that determines packet loss;
It is characterized by providing.

The invention according to claim 5 is the receiving apparatus according to claim 4,
The information processing apparatus further includes notification means for notifying a user of a determination result by the determination means.

  According to the present invention, a plurality of specific packets are inserted into a series of stream packets to which an authenticator is added, and authentication is included between each specific packet and a specific packet adjacent in the predetermined stream direction of the series of stream packets. Since the stream including the information indicating the number of stream packets to be used for transmission / reception is transmitted / received, when authentication fails, the reception side and the number of stream packets to be used for authentication included in the received specific packet and the stream Number of stream packets actually received among the stream packets related to the number of packets (stream packets to be used for authentication between the specific packet and the specific packet adjacent to the specific packet in the predetermined stream direction) Or the comparison result , Failure cause of authentication, seemingly due to tampering, it is possible to identify seemingly due packet loss. Therefore, it is possible to appropriately cope with the cause of the authentication failure without giving the user anxiety.

It is a figure which shows the example of a stream transmitted by the transmitter which concerns on one embodiment of this invention. It is a functional block diagram which shows the structure of the principal part of the transmitter which concerns on one embodiment of this invention. It is a functional block diagram which shows the structure of the principal part of the receiver which concerns on one embodiment of this invention which receives the stream shown in FIG. FIG. 4 is a flowchart for explaining an operation of the receiving apparatus illustrated in FIG. 3. FIG. FIG. 4 is a diagram illustrating a display example when authentication fails due to tampering in the receiving apparatus illustrated in FIG. 3. FIG. 4 is a diagram illustrating a display example when authentication fails due to packet loss in the receiving apparatus illustrated in FIG. 3. It is a figure for demonstrating an example of the message authentication method by a streaming transfer system. It is a figure for demonstrating the other example of the message authentication method by a streaming transfer system. It is a figure for demonstrating the further another example of the message authentication method by a streaming transfer system.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating an example of a stream transmitted by a transmission apparatus according to an embodiment of the present invention. The stream 1 shown in FIG. 1 includes a signed message packet 10 that is a series of stream packets generated by packetizing a transmission message, and a specific identification that is inserted into the series of signed message packets 10 at arbitrary intervals, that is, at random. The counter packet 20 is a packet.

  The signed message packet 10 is calculated using the original message 11, the original message 11 and the hash value of the immediately preceding packet in the same manner as in FIG. 8 in order to guarantee the security of the message and authenticate the entire stream. And a message authenticator 12 composed of the hash value.

  The counter packet 20 has an ID 21 indicating that it is a counter packet, and the number of transmissions of the signed message packet 10 from the counter packet 20 to the counter packet 20 in the predetermined stream direction, here the previous (past) counter packet (the number of authentication target packets). ) 22.

  In FIG. 1, the right side represents the latest time t. Accordingly, when the middle counter packet 20 is transmitted, the number of transmissions of the signed message packet 10 from the left (immediately preceding) counter packet 20 transmitted before that time is “3”. “3” is inserted into the number of authentication target packets 22 and transmitted. When the right counter packet 20 is transmitted, the number of transmissions of the signed message packet 10 from the middle (immediately preceding) counter packet 20 transmitted before that is “4”. “4” is inserted into the number of authentication target packets 22 and transmitted.

  FIG. 2 is a functional block diagram showing a configuration of a main part of a transmission apparatus according to an embodiment of the present invention that transmits the stream 1 shown in FIG. The transmission apparatus 100 according to the present embodiment includes a hash value calculation unit 101, a counter 102, a memory 103, a packet generation unit 104, and a transmission unit 105.

  The transmission apparatus 100 calculates, for example, a hash value calculation unit 101 using only the original message and stores it in the memory 103 for the packetized original message to be added with a signature. For the second and subsequent original messages to be added with the signature, the hash value calculation unit 101 uses the original message and the hash value in the immediately preceding signed message packet stored in the memory 103 to generate the original message. A hash value for the message is calculated and stored in the memory 103.

  Each time the hash value calculation unit 101 calculates a hash value, the hash value calculation unit 101 notifies the counter 102 that the calculation has been performed. As a result, the counter 102 increments the number of authentication target packets having an initial value of 0 and stores the count value in the memory 103. In addition, every time the hash value calculation unit 101 calculates a hash value, the hash value calculation unit 101 notifies the packet generation unit 104 to that effect.

  As a result, the packet generation unit 104 adds the corresponding hash value stored in the memory 103 to the original message as a message authenticator, and generates a signed message packet 10 (see FIG. 1). The signed message packet 10 is transmitted to the transmission unit 105 and transmitted from the transmission unit 105 to a network (not shown).

  Further, the packet generation unit 104 generates a counter packet 20 (see FIG. 1) including the number of transmitted authentication target packets stored in the memory 103 at an arbitrary timing. The counter packet 20 is transmitted to the transmission unit 105 and is transmitted from the transmission unit 105 to the network in the same manner as the signed message packet 10. The count value of the counter 102 is reset to the initial value 0 every time the counter packet 20 is transmitted.

  Therefore, in the present embodiment, the hash value calculation unit 101, the counter 102, the memory 103, and the packet generation unit 104 constitute a stream generation unit, and the transmission unit 105 constitutes a transmission unit.

  As described above, in this embodiment, a plurality of counter packets 20 are inserted into a series of signed stream packets 10, and the number of authentication target packets included between the immediately preceding counter packets 20 is included in each counter packet 20. Since the stream 1 including the indicated information is generated and transmitted, it is possible to identify the cause of the authentication failure by appropriately using the counter packet 20 on the receiving side. Further, by inserting a plurality of counter packets 20 at random, it is possible to prevent the stream 1 from being tampered with and to further improve the safety of the entire stream.

  FIG. 3 is a functional block diagram showing a configuration of a main part of a receiving apparatus according to an embodiment of the present invention that receives the stream 1 shown in FIG. The receiving apparatus 200 according to the present embodiment includes a receiving unit 201, a hash value calculating unit 202, a counter 203, a memory 204, a counter packet processing unit 205, an authentication unit 206, a decoder 207, a display unit 208, and a speaker 209.

  Hereinafter, the operation of the receiving apparatus 200 will be described with reference to the flowchart shown in FIG. 4 taking as an example a case where a stream having audio and images is viewed. The receiving device 200 first receives a packet from the network at the receiving unit 201 (step S1). If the received packet is a signed message packet according to its type, the received packet is sent to the hash value calculating unit 202 as a counter packet. For example, the packet is sent to the counter packet processing unit 205 (step S2).

  The hash value calculation unit 202 extracts the original message from the signed message packet, and when the signed message packet is the first packet, for example, calculates the hash value using only the extracted original message (step S3). The calculated hash value is stored in the memory 204.

  On the other hand, if the signed message packet is the second or subsequent packet, the hash value calculation unit 202 sends the original message extracted from the signed message packet and the immediately preceding signed message stored in the memory 204. Using the hash value in the packet, the hash value in the original message is calculated (step S3), and the calculated hash value is stored in the memory 204.

  Further, every time the hash value calculation unit 202 calculates a hash value, the hash value calculation unit 202 notifies the counter 203 to that effect. As a result, the counter 203 increments the number of hash calculation packets having an initial value of 0, that is, the number of actually received signed message packets (step S4), and stores the count value in the memory 204.

  The authentication unit 206 compares the hash value calculated by the hash value calculation unit 202 and stored in the memory 204 with the hash value added to the received signed message packet for the received signed message packet. Then, it is determined whether or not they match (step S5).

  As a result, if the hash values match, the authentication is successful and the original message of the received signed message packet is decoded by the decoder 207 and supplied to the display unit 208 and the speaker 209 to continue viewing (step S6). ). Thereafter, the authentication unit 206 determines whether or not the stream has ended (step S7). If it has not ended, the process returns to step S1, and if it has ended, the reception operation of the stream ends normally.

  On the other hand, if the hash values do not match in step S5, it is determined that the authentication has failed, the message is discarded without being transmitted to the decoder 207, and viewing by the display unit 208 and the speaker 209 is stopped (step S8). ).

  After it is determined that the authentication has failed, until the reception unit 201 receives a counter packet, the hash value calculation unit 202 notifies the counter 203 that the received packet is a signed message packet. Based on the notification from the hash value calculation unit 202, the received number of signed message packets is incremented and the count value is stored in the memory 204 (steps S9 to S11).

  When the reception unit 201 receives the counter packet (YES in step S10), the counter packet processing unit 205 extracts the number of authentication target packets from the received counter packet and stores it in the memory 204 (step S12). 206 compares the number of authentication target packets stored in the memory 204 with the count value of the counter 203 stored in the memory 204, and determines whether or not the count value matches the number of authentication target packets ( Step S13).

  As a result, if the count value of the counter 203 matches the number of packets to be authenticated, it is determined that the message has been tampered with and an invalid stream is displayed on the display unit 208, for example, as shown in FIG. Then, as shown in FIG. 5 (b), after displaying “Unable to authenticate due to falsification, forcibly terminate” (step S14), the reception processing is stopped so as not to view the falsified data ( Step S15), the reception operation is forcibly terminated.

  On the other hand, in step S13, when the count value of the counter 203 is less than the number of authentication target packets, or when the count value of the counter 203 exceeds the number of authentication target packets, the display unit 208 displays, for example, FIG. As shown in FIG. 6 (b), “No authentication due to packet loss” is displayed (step S16), the reception process is stopped (step S15), and the reception operation is forced. finish. 5 and 6 show display examples when the receiving device 200 is a mobile terminal.

  Therefore, in the present embodiment, the reception unit 201 constitutes a reception unit, and includes a hash value calculation unit 202, a memory 204, and an authentication unit 206, and constitutes an authentication unit. The memory 204 and the authentication unit 206 include a comparison unit. And a determination unit, and an authentication unit 206 and a display unit 208 are included to form a notification unit.

  Thus, in the present embodiment, a plurality of counter packets 20 inserted into a series of signed stream packets 10 are included, and each counter packet 20 includes an authentication target packet included between the immediately preceding counter packet 20. When the stream 1 including the information indicating the number is received and the stream authentication fails, the total number of transmitted authentication target packets included in the counter packet 20 and the signed stream packet 10 actually authenticated is included. When the numerical values are compared and they do not match, the user can be notified that there is a possibility of packet loss.

  If the count value of the signed stream packet 10 that is actually authenticated is larger than the number of transmitted authentication target packets included in the counter packet 20, the counter packet immediately before the counter packet 20 may have been lost. It can be determined that there is a packet, and it can be determined that it is impossible to determine whether or not there is a loss of the authentication target packet due to the loss of the counter packet. Here, if there is a loss in the counter packet, it is determined that there is a high possibility that the packet to be authenticated has also been lost (especially in the case of wireless, the packet is often lost in bursts). "Authentication is not possible."

  Therefore, since it is highly likely that the stream is valid in the case of authentication failure simply due to packet loss, the user can easily determine the next action to be taken, such as starting reception processing again. There is no longer anxiety that the received data has been received.

  In addition, this invention is not limited only to the said embodiment, Many deformation | transformation or a change is possible. For example, in the above embodiment, even when the cause of the authentication failure is due to packet loss, the reception process is stopped and forcibly terminated. In this case, for example, the stream is continuously received and authentication is resumed. Therefore, since there is a possibility that the authentication is successful, it is possible to reset the counter 203 and the memory 204 and continue the reception operation.

  Further, a sequence number is added to the counter packet 20 to manage the packet loss of the counter packet itself, and the result can be used for the comparison determination process in step S9 of FIG. 4 when the authentication fails. . In this way, when the count value of the signed stream packet 10 that has actually been authenticated exceeds the number of packets to be authenticated included in the counter packet 20, the cause is due to the loss of the counter packet. Or the result of falsification (if the sequence number is correct but the count value of the signed stream packet 10 exceeds the number of packets to be authenticated included in the counter packet 20) It can be determined that a stream has been inserted).

  Further, according to the present invention, as in the above embodiment, the hash value of the signed message packet 10 is calculated in association with the hash value of the previous signed message packet as shown in FIG. However, the present invention is not limited to this, and can be effectively applied to the case where the hash value of two packets before is calculated and transmitted / received as shown in FIG.

  Further, the number of authentication target packets to be inserted into the counter packet 20 is not limited to the number of transmissions of the signed message packet 10 up to the previous (past) counter packet 20, but the signed message packet 10 transmitted up to the next counter packet 20. The number of transmissions can also be used.

  Further, the counter packet 20 is not limited to being inserted at an arbitrary interval as in the above-described embodiment, and can be inserted at a constant interval or according to a predetermined rule. The interval can also be set as appropriate according to the desired detection speed of the cause of authentication failure. Further, in the above embodiment, the counter packet 20 is generated independently of the signed message packet 10. However, the authentication object to be notified by the counter packet 20 without generating such a counter packet 20. The number of packets may be added to the signed message packet 10 as a specific packet and transmitted / received. In addition, the number of authentication target packets between the specific signed message packets 10 may be included in the specific signed message packet 10.

  In the above embodiment, the stream packets are all signed, that is, the stream packets between the counter packets are all signed stream packets (stream packets to be authenticated). Only packets, eg, data broadcast packets, may be signed. That is, only data broadcast packets may be handled as signed stream packets (stream packets to be authenticated). In this case, of the stream packets between the counter packets, only the data broadcast packet is a stream packet with authentication (stream packet to be authenticated). Of course, as a predetermined type of packet, only a video packet may be a signed stream packet, or only an audio packet may be a signed stream packet.

1 stream 10 signed message packet 11 original message 12 message authenticator 20 counter packet 21 ID
22 Number of packets to be authenticated 100 Transmitting device 101 Hash value calculating unit 102 Counter 103 Memory 104 Packet generating unit 105 Transmitting unit 200 Receiving device 201 Receiving unit 202 Hash value calculating unit 203 Counter 204 Memory 205 Counter packet processing unit 206 Authentication unit 207 Decoder 208 Display unit 209 Speaker

The present invention relates to a transmission equipment for transferring data to be authenticated by the streaming transfer method.

Therefore, an object of the present invention made in view of such a point is that data can be transferred so that the cause of the authentication failure can be identified, and the receiving side can appropriately respond to the cause of the authentication failure without giving the user anxiety. to provide a transmission equipment which can deal with.

The invention of the transmitter according to claim 1 that achieves the above object is as follows:
A plurality of specific packets are inserted into a series of stream packets to which an authenticator is added, and each of the specific packets is one of the stream packets included between the specific packets adjacent in the predetermined stream direction of the series of stream packets. Stream generation means for generating a stream by including information indicating the number of stream packets to be used for authentication as a part ;
Transmitting means for transmitting the stream generated by the stream generating means;
It is characterized by providing.

It is a figure which shows the example of a stream transmitted by the transmitter which concerns on one embodiment of this invention. It is a functional block diagram which shows the structure of the principal part of the transmitter which concerns on one embodiment of this invention. It is a functional block diagram showing a configuration of a main portion of a receiving device that will receive the stream shown in FIG. FIG. 4 is a flowchart for explaining an operation of the receiving apparatus illustrated in FIG. 3. FIG. FIG. 4 is a diagram illustrating a display example when authentication fails due to tampering in the receiving apparatus illustrated in FIG. 3. FIG. 4 is a diagram illustrating a display example when authentication fails due to packet loss in the receiving apparatus illustrated in FIG. 3. It is a figure for demonstrating an example of the message authentication method by a streaming transfer system. It is a figure for demonstrating the other example of the message authentication method by a streaming transfer system. It is a figure for demonstrating the further another example of the message authentication method by a streaming transfer system.

Figure 3 is a functional block diagram showing a configuration of a main portion of a receiving device that will receive the stream 1 shown in FIG. The receiving device 200 illustrated in FIG. 3 includes a receiving unit 201, a hash value calculating unit 202, a counter 203, a memory 204, a counter packet processing unit 205, an authentication unit 206, a decoder 207, a display unit 208, and a speaker 209.

Therefore, in the receiving apparatus 200 illustrated in FIG. 3 , the receiving unit 201 constitutes a receiving unit, and the authentication unit includes the hash value calculation unit 202, the memory 204, and the authentication unit 206. A comparison unit and a determination unit are included, and an authentication unit 206 and a display unit 208 are included to form a notification unit.

As described above, according to the receiving apparatus 200 of FIG. 3, a plurality of counter packets 20 inserted into a series of signed stream packets 10 are included, and each counter packet 20 is included between the last counter packet 20. When the stream 1 including the information indicating the number of authentication target packets is received and the stream authentication fails, the number of transmitted authentication target packets included in the counter packet 20 and the stream packet with a signature that has been actually authenticated When the count values of 10 are compared and do not match, it is possible to notify the user that there is a possibility of packet loss.

In addition, this invention is not limited only to the said embodiment, Many deformation | transformation or a change is possible. For example, in the above description , even when the cause of the authentication failure is due to packet loss, the reception process is stopped and forcibly terminated, but in this case, for example, by continuously receiving the stream and restarting the authentication, Since authentication may be successful, the counter 203 and the memory 204 can be reset to continue the reception operation.

Claims (5)

A plurality of specific packets are inserted into a series of stream packets to which an authenticator is added, and each specific packet is a stream packet to be used for authentication included between adjacent packets in the predetermined stream direction of the series of stream packets. Stream generation means for generating a stream including information indicating a number;
Transmitting means for transmitting the stream generated by the stream generating means;
A transmission device comprising:   The transmission apparatus according to claim 1, wherein the stream generation unit inserts the plurality of specific packets at an arbitrary stream packet interval. It has a plurality of specific packets inserted in a series of stream packets to which an authenticator is added, and is used for authentication included between each specific packet and a specific packet adjacent in the predetermined stream direction of the series of stream packets. A receiving method for receiving a stream generated by including information indicating the number of stream packets to be processed,
Authenticate the received stream packet;
When authentication fails, the number of stream packets to be used for authentication included in the received specific packet and the authentication received between the specific packet and a specific packet adjacent in the predetermined stream direction of the specific packet are used. When the number of stream packets to be used for the received authentication matches the number of stream packets to be used for the authentication included in the specific packet based on the comparison with the number of stream packets to be determined, the stream is regarded as an invalid stream. If the number of stream packets to be used for the received authentication is less than the number of stream packets to be used for the authentication included in the specific packet, it is determined that the packet is lost.
And a receiving method. It has a plurality of specific packets inserted in a series of stream packets to which an authenticator is added, and is used for authentication included between each specific packet and a specific packet adjacent in the predetermined stream direction of the series of stream packets. Receiving means for receiving a stream generated including information indicating the number of stream packets to be transmitted;
Authentication means for performing stream authentication using the stream packet received by the receiving means;
A counter that counts the number of stream packets to be used for the authentication received by the receiving means between sequential specific packets received by the receiving means;
A comparison means for comparing the number of stream packets to be used for authentication contained in the specific packet received by the receiving means and the value of the counter when the authentication by the authentication means fails;
If the value of the counter matches the number of stream packets to be used for authentication included in the specific packet based on the comparison result by the comparison means, the stream is determined to be an invalid stream, and the value of the counter Is smaller than the number of stream packets to be used for authentication included in the specific packet, a determination unit that determines packet loss;
A receiving apparatus comprising: The receiving apparatus according to claim 4, further comprising notification means for notifying a user of a determination result by the determination means.

Images