JP5503892B2 - Emergency information transmitter and receiver for digital terrestrial television broadcasting - Google Patents

Description

  The present invention relates to a technology for transmitting and receiving emergency information in terrestrial digital television broadcasting, and in particular, a transmission device that allows only authorized operators to use transmission or reception of emergency information such as emergency warning broadcasting and emergency earthquake warnings. And a receiving apparatus.

  The Japan Meteorological Agency started providing emergency earthquake bulletins (see Non-Patent Document 1, for example) to the general public from October 1, 2007. Accordingly, television and radio broadcasting stations are also broadcasting such as displaying or sounding them on a television screen together with a chime sound when the breaking news is announced. In addition, a part of the earthquake early warning radio broadcast started on April 1, 2008.

  In the case of emergency alert broadcasting, a mechanism is known that operates with reduced standby power consumption and activates a receiving device that is not turned on to notify the receiving device. For example, an ISDB-T (Integrated Services Digital Broadcasting-Terrestrial, ARIB standard STD-B31) type terrestrial digital television receiving apparatus has a TMCC (Transmission and Transmission) function when power is not supplied during normal operation of the receiving apparatus. Multiplexing Configuration Control: Transmission control) By providing a reception function for a transmission control signal that detects an emergency warning broadcast activation flag stored in a carrier, when the emergency warning broadcast activation flag is 1 (there is an emergency warning broadcast) The power supply of the receiving device can be turned on to prompt the receiving device to view the emergency alert broadcast (see, for example, Patent Document 1).

  Furthermore, it is disclosed that when the receiving device is not turned on, or when other channels are received, it is urged to turn on the power or switch the channel at the time of emergency information. There has been proposed a technique for receiving a TMCC signal and an AC signal and reproducing other disaster / disaster prevention information and video / audio after power-on or channel switching (see, for example, Patent Document 2).

JP 2006-319771 A JP 2007-243936 A

“Technical reference materials on overview and processing methods of earthquake early warnings,” Japan Meteorological Agency Earthquake Volcano, [Search on January 31, 2008], Internet <URL: http://www.seisvol.kishou.go.jp/ eq / EEW / kaisetsu / Whats_EEW / reference.pdf>

  None of the above-described techniques provide a technique for authenticating a business operator who presents automatic activation of emergency information in digital terrestrial television broadcasting.

  For example, in the case of a partial reception segment method (so-called one-segment transmission / reception device), any user of this transmission / reception device receives emergency information even if it is a weak radio wave and retransmits it to another arbitrary reception device It is also possible to make it. Therefore, there is a risk that emergency information such as earthquake early warnings may be misused and retransmitted (replay attack), which may cause social problems.

  Therefore, an object of the present invention is to provide a transmission device and a reception device that can be used only by an authorized business operator when using a transmission system that transmits and receives emergency information in digital terrestrial television broadcasting.

  In order to achieve the above object, the present invention provides a service for providing a service to an unspecified number of users even in transmission of emergency information using a limited number of bits (204 bits) of a transmission control signal (TMCC or AC signal). Among them, only a predetermined business operator provides a transmission device or a reception device that enables transmission and reception of emergency information, and in particular, secretly between the business operator's transmission device and the reception device in advance. The contents of emergency information can be verified using the stored random number sequence.

  A transmission device according to the present invention is a transmission device that transmits emergency information by a transmission control signal of a terrestrial digital television broadcast wave, and includes telegraphic information including an activation signal for identifying the presence or absence of emergency information and the emergency information. Urgent information generating means for generating and urgent information transmitting means for transmitting the telegram information by a transmission control signal of digital terrestrial television broadcast waves, the emergency information generating means from the random number sequence defined in advance, A means for selecting and generating an authentication random number sequence determined by transmission time information when transmitting information and the authentication random number sequence are used for authentication of time information related to the emergency information and an operator transmitting the emergency information. Means for code-converting data including authentication information and cyclic redundancy check information to generate an authenticator, and means for including the authenticator in emergency information And wherein the Rukoto.

  In the transmitter of the present invention, the authentication random number sequence is a predetermined number of bits from a bit position in the predetermined random number sequence determined from a specific function by transmission time information when transmitting the emergency information. It consists of minutes.

  In the transmission apparatus of the present invention, the predetermined random number sequence and the specific function are common between transmission and reception.

  Further, in the transmitting device of the present invention, the authenticator is generated by performing exclusive OR with the number of bits of both the authentication random number sequence and the data constituting the authenticator being aligned. And

  In the transmitting apparatus of the present invention, the authenticator is encrypted using time information such as a transmission time or an earthquake occurrence time when transmitting the emergency information as key information.

  In the transmission device of the present invention, the time information related to the emergency information includes an earthquake occurrence time or a transmission time distributed from the Japan Meteorological Agency.

Furthermore, the receiving device of the present invention is a receiving device that receives emergency information by a transmission control signal of a terrestrial digital television broadcast wave, and includes a start signal for identifying presence / absence of emergency information and a telegram including the emergency information. Signal extraction means for extracting information from the transmission control signal, activation signal verification means for verifying the presence or absence of the emergency information from the activation signal, and emergency information for verifying the emergency information when the emergency information is present Verification means, and the emergency information verification means includes a plurality of verification purposes determined by a time lag between the reception time information when receiving the emergency information and the assumed transmission time information from a predetermined random number sequence. means for generating and selecting a random number sequence, by the plurality of verification random number sequence, the predefined authenticator in the emergency information and code conversion, time information related to the emergency information, Authentication information used for authentication of the operator transmitting the emergency information, means for restoring data including information on cyclic redundancy check, time information related to the emergency information, authentication used for authentication of the operator transmitting the emergency information And means for extracting and inspecting information and information of the cyclic redundancy check.

  Further, in the receiving device of the present invention, the emergency information verification unit inspects time information related to the emergency information, authentication information used for authentication of a provider transmitting the emergency information, and information on the cyclic redundancy check. It is further characterized by further comprising warning generating means for issuing a warning about the emergency information when it is determined to be valid.

  In the receiving apparatus of the present invention, the verification random number sequence is a predetermined bit from a bit position in the predetermined random number sequence determined from a specific function by reception time information when the emergency information is received. It consists of several minutes.

  In the receiving apparatus of the present invention, the predetermined random number sequence and the specific function are common between transmission and reception.

  Further, in the receiving device of the present invention, the authenticator is generated by performing exclusive OR by aligning the number of bits of both the authentication random number sequence and the data constituting the authenticator, and The information verification means restores the authenticator by performing an exclusive OR with the verification random number sequence.

  Further, in the receiving device of the present invention, the authenticator is encrypted using time information such as a transmission time or an earthquake occurrence time when transmitting the emergency information as key information, and the emergency information verification means includes the The authenticator is restored using reception time information when receiving emergency information as key information.

  In the receiving device of the present invention, the time information related to the emergency information includes an earthquake occurrence time or a transmission time distributed from the Japan Meteorological Agency.

  According to the present invention, only a business operator that holds a specific random number sequence can create valid emergency information. In particular, on the transmission side, since the random number to be used changes according to the time information used for authentication, it is difficult to use the same information multiple times, and the safety against replay attacks can be improved. Further, it is possible to make it difficult for an attacker to guess a random number sequence that is secret information.

  In addition, according to the present invention, it is configured to perform collation of time information and an operator by a random number sequence even when an emergency information activation signal is received from a received broadcast wave and it is determined that there is emergency information. Therefore, it is possible to automatically determine that the emergency information is not provided by an authorized business operator.

It is the schematic which shows the transmission system provided with the provider transmission apparatus and receiving apparatus of one Example by this invention. It is a figure which shows the provider transmission apparatus of one Example by this invention. It is a functional block diagram of the emergency information production | generation part in the provider transmission apparatus of one Example by this invention. It is message | telegram information which shows an example in the AC signal transmitted in the provider transmission apparatus of one Example by this invention. It is a figure which shows the receiver of one Example by this invention. It is a functional block diagram of the emergency information verification generation part in the receiver of one Example by this invention. It is a flowchart which shows operation | movement of the provider transmission apparatus of one Example by this invention. It is a flowchart which shows operation | movement of the receiver of one Example by this invention. It is operation | movement explanatory drawing of the provider transmission apparatus and receiving apparatus of one Example by this invention.

  First, a provider transmission device and a reception device according to an embodiment of the present invention will be described.

  FIG. 1 is a schematic diagram illustrating a transmission system including a provider transmission device and a reception device according to an embodiment of the present invention. The specific provider transmission device 1 uses a TMCC signal or an AC signal, and a plurality of reception devices 3-1, 3-2, 3-3 (generally referred to as reception device 3) via the repeater 2. Send emergency information to In FIG. 1, only three receiving apparatuses are shown, but any number can be used.

  The business owner owns the business enterprise transmission device 1 that transmits the program, and can transmit, for example, a one-seg type reception side automatic activation activation signal and a message to be displayed after activation to the reception device 3 using broadcast waves. it can. The receiving device 3 receives a start signal for starting one seg transmitted from a business operator through a broadcast wave, starts the receiving device 3, and displays a message.

  It is effective to use a TMCC carrier or an AC carrier to transmit emergency information with a low delay by using a terrestrial digital broadcast wave. This is because time interleaving is not used for TMCC signals and AC signals. In the following description, an example in which emergency information is transmitted using an AC signal will be described.

  FIG. 2 is a diagram illustrating the business entity transmitter 1 according to an embodiment of the present invention. The provider transmission device 1 according to an embodiment includes an emergency information generation unit 11, an error correction coding unit 12, a remultiplexing unit 13, and a modulation unit 14.

  The emergency information generation unit 11 generates emergency information in a predetermined message format exemplified below, based on emergency bulletins such as emergency earthquake bulletins distributed from the Japan Meteorological Agency.

  The error correction coding unit 12 uses, for example, a short code (187, 105) of the difference set cyclic code (273, 191) for the information in the message including the emergency information generated by the emergency information generation unit 11 to use the error correction code. To generate a parity bit and generate an AC signal to be transmitted. In this case, since error correction of about 8 bits is possible, the reliability of information can be improved and more reliable transmission can be achieved.

  The remultiplexing unit 13 remultiplexes the generated AC signal into a TS (transport stream) to be transmitted.

  The modulation unit 14 modulates the remultiplexed TS and outputs it as a broadcast wave.

  Although the function in the provider transmission device 1 is typically exemplified, except for the information generation in the AC signal, a configuration conforming to a terrestrial digital television system (for example, ISDB-T system) can be adopted. Therefore, the emergency information generation unit 11 according to the present invention will be described in detail below.

  FIG. 3 is a functional block diagram of the emergency information generation unit 11 in the transmission apparatus according to the embodiment of the present invention. Moreover, FIG. 4 illustrates the telegram information in the AC signal transmitted in the provider transmission device 1 according to an embodiment of the present invention.

  The business entity transmitter 1 according to an embodiment of the present invention uses an AC signal, which is one of transmission control signals, to collect emergency information (hereinafter, information including emergency warning broadcasts and emergency earthquake warnings). Urgent information is transmitted by the AC signal.

  For example, in the case of the mode 3 synchronous modulation section of the partial reception segment (segment number # 0) of the ISDB-T terrestrial digital television broadcast wave, the AC signal is carrier numbers # 7, # 89, # 206, # 209. , # 226, # 244, # 377 and # 407 are signals carried by AC carriers at eight locations, and emergency information is transmitted by at least one of these AC carriers.

  That is, 204 bits of the DBPSK signal with respect to the same 204 symbols as the TMCC signal on the basis of one symbol of the OFDM (Orthogonal Frequency Division Multiplexing) system so as to have the same frame length as the TMCC signal which is one of the transmission control signals. To the same differential demodulation standard and synchronization signal as the TMCC signal, an activation signal for identifying the presence of emergency earthquake warning, an update flag for identifying whether emergency information has been updated, and an earthquake The telegram information (the format of telegram information exemplified in Table 1) for storing emergency information including information on breaking news is defined. Further, the error correction encoding unit can apply error correction codes to the activation signal, the update flag, and the emergency information, and add parity bits.

  In order to facilitate understanding of the present invention, a case will be described below where at least one of AC information carried by a mode 3 AC carrier in ISDB-T digital terrestrial television broadcasting is used. Note that it is also applicable in mode.

  Referring to FIG. 3, the emergency information generation unit 11 includes a current time code generation unit 111, an authentication random number sequence generation unit 112, an authenticator generation unit 113, and an emergency information setting unit 114.

  The authentication random number sequence generation unit 112 includes a random number generation unit 1121 and a random number sequence bit position determination unit 1122.

  The authenticator generation unit 113 includes a time information setting unit 1131, an authentication information setting unit 1132, and a CRC generation unit 1133.

  The current time code generation unit 111 generates a code in which (year), month, day, hour, minute, and second of the transmission time (or current time) for transmitting emergency information are arranged.

  The authentication random number generation unit 112 includes an authentication random number sequence having a predetermined number of bits from the specified bit position obtained by the random number sequence bit position determination unit 1122 among the random number sequences obtained by the random number generation unit 1121 (that is, , An authentication random number sequence determined by transmission time information when transmitting emergency information is selected and generated, and is sent to the authenticator generation unit 112.

  The random number generation unit 1121 is a functional unit that creates a common random number sequence (or pseudo random number sequence) between transmission and reception (between the provider transmission device and the reception device of the present embodiment). For example, a random number sequence (for example, 100 kbytes or more) common between transmission and reception is generated and stored using a pseudo-random number generator that is secure in cryptographic theory. Alternatively, instead of the random number generation unit, a random number sequence prepared in advance can be kept secret in common between transmission and reception.

  The random number sequence bit position determination unit 1122 has a function of specifying the bit position in the random number sequence from the time code generated by the current time code generation unit by a specific function f (t) that is secretly held in common between transmission and reception. . Therefore, the random number sequence for authentication consists of a predetermined number of bits from a bit position in a predetermined random number sequence determined from a specific function by transmission time information when transmitting emergency information. This specific function f (t) is common between transmission and reception, and can specify the bit position from the same random number sequence between transmission and reception to derive the same authentication / verification random number sequence between transmission and reception. Any function such as a non-linear function such as a hash function or a linear function such as a multidimensional function may be used. A function that outputs a random value with respect to an input, such as a hash function, is desirable.

  The time information setting unit 1131 sets “time information” composed of “earthquake occurrence time” or “current time” as information in the “authenticator” in the transmitted message information.

  The authentication information setting unit 1132 can transmit, for example, an “authentication information” that can include an emergency information message generated by an operator or is kept secret between transmission and reception separately from the emergency information message. Set as information in the "authenticator" in the information.

  The CRC generation unit 1133 adds a CRC (Cyclic Redundancy check) code to the “time information” and “authentication information”, and sets the information as “authenticator” in the transmitted message information.

  The authenticator generation unit 113 includes data including “time information” related to the emergency information to be set, “authentication information” used for authentication of a carrier transmitting the emergency information, and “CRC (Cyclic Redundancy Check)” information. The code is converted to generate an authenticator and sent to the emergency information setting unit 114. As the code conversion here, the authenticator is encrypted using time information such as a transmission time or an earthquake occurrence time when transmitting emergency information as key information, or a random number sequence for authentication and authentication information. Etc. (for example, the earthquake occurrence time and the operator code) can be generated by performing exclusive OR with the same number of bits of both data.

  The emergency information setting unit 114 sets the emergency information including the authenticator generated by the authenticator generating unit 113 in the message information transmitted using the AC carrier.

  With reference to FIG. 4, the structure of the message | telegram conveyed by AC carrier is demonstrated.

The “differential demodulation reference” is a value based on the same generator polynomial (x ¹¹ + x ⁹ +1) as the value W _{k of the} BPSK signal assigned to the SP signal of the carrier number k, similarly to the TMCC signal. In the case of an AC carrier (synchronous modulation unit in mode 3) in a partial reception segment (segment number # 0) of an ISDB-T terrestrial digital television broadcast wave, carrier numbers # 7, # 89, # 206, # 209, # It is a value assigned to eight locations of 226, # 244, # 377 and # 407. W _k stored as the reference of differential demodulation described in the AC information carried by the eight AC carriers is 0, 0, 0, 0, 0, 1, 1, and 0, respectively.

The “synchronization signal” is a 16-bit synchronization signal, and the value thereof is “0011010111101110” (odd frame) and its inverse (even frame), which are different values in the odd and even frames. In the DBPSK modulated wave, when W _k is 0, odd frames are “1, 1, −1, 1, 1, −1, −1, 1, −1, 1, −1, −1, 1, − 1, 1, 1 "and even frames are" -1, 1, 1, 1, -1, -1, 1, 1, 1, 1, 1, -1, -1, -1, -1, 1 ”. When W _k is 1, these are inverted. Thus, the “synchronization signal” is a signal having a known amplitude and phase.

  A 1-bit (or 2 bits) “activation signal” for identifying the presence or absence of emergency information follows the “synchronization signal”. The value of the “activation signal” is the value representing the bit of “1” when there is emergency information, the phase of the last symbol of the “synchronization signal” is inverted, and “0” when there is no emergency information. The phase continues as a value representing the bits of.

  The “update flag” is composed of 2 bits, for example, and is incremented every time the content of the emergency information is updated, and is used to identify whether or not the content of the emergency information is updated by circulating. As another example, by using an “update flag” (1 bit) whose value is updated (updated from 1 to 0 or from 0 to 1) each time the content of transmitted emergency information is updated. If the control is performed so that the receiving operation is performed only at the time of update, the internal processing amount of the receiving device 1 receiving the emergency information can be efficiently reduced. Alternatively, the “update flag” can be set to start with the same value as the flag value at the time of activation of the “activation signal” in order to provide further redundancy of the “activation signal”. As described above, the “update flag” can be set to 1 bit when the content of the emergency information is updated while the “activation signal” continues the value indicating that the emergency information exists. When the update frequency is two or more in actual operation, two or more bits can be assigned to the “update flag”.

  In the above example, the emergency information is made up of, for example, an emergency information identification signal, various identification signals, and an authenticator. It can be configured to transmit in a frame of an AC signal.

  The “emergency information identification signal” is a signal indicating the type of emergency information. Information is provided as to whether the emergency information represents an earthquake early warning or an emergency warning broadcast. For example, the number of bits to be allocated is 3 bits, “000” is an emergency earthquake warning, “001” is an emergency warning broadcast, “010” is an emergency earthquake warning test signal, and “011” is an emergency warning broadcast test signal. Similar to the “activation signal”, each 3-bit value is transmitted as a DBPSK-modulated value. For example, when the “activation signal” indicates a value of “1” (emergency information is present), the value of the “emergency information identification signal” is read to determine the type of emergency information, that is, what kind of emergency information is included. Can be identified.

  The “various identification signals” are information signals accompanying emergency information such as “breaking ID” (12 bits), “information number” (4 bits), “message type” (2 bits), and signals such as broadcaster identification. Is applicable.

  In the following description, the “authenticator” is assumed to be composed of “earthquake occurrence time”, “authentication information”, and “CRC (Cyclic Redundancy check)”.

  The “earthquake occurrence time” is created by arranging the year, month, day, hour, minute, and second in accordance with, for example, the earthquake early warning published by the Japan Meteorological Agency.

  The “authentication information / message” is an area for storing, for example, authentication information for identifying a business operator (for example, business operator code) and a message of emergency information generated by the business operator. Authentication and verification are performed between transmission and reception. It is also possible to store the data by performing encryption for performing.

  “CRC” is an area for storing a CRC code used for verification of a transmission source.

  It should be noted that the “authenticator” can be configured in various ways. For example, the “earthquake occurrence time”, “authentication information”, and “CRC” can be configured with an arbitrary number of bits. Further, instead of “earthquake occurrence time”, “current time” representing the time for transmitting emergency information can be used. Alternatively, the “authentication information” may be “earthquake occurrence time”. In addition, the “authenticator” may be composed only of “time information” including “earthquake occurrence time” or “current time” and “CRC”.

  Next, a receiving apparatus according to an embodiment of the present invention will be described.

  FIG. 5 is a schematic diagram of a receiving apparatus according to an embodiment of the present invention. FIG. 6 is a schematic diagram of an authenticator verification unit in the receiving apparatus according to an embodiment of the present invention.

  The receiving device 3 according to the present embodiment includes an RF receiving unit 32, a signal extracting unit 33, an activation signal verifying unit 34, an emergency information verifying unit 35, and a warning generating unit 36.

  The RF reception unit 32 receives a broadcast wave (radio frequency signal) transmitted from the provider transmission device of the embodiment via the antenna 31 and sends it to the signal extraction unit 33.

  The signal extraction unit 33 establishes synchronization using the “synchronization signal” from the signal received from the RF reception unit 32, for example, demodulates and extracts an AC signal in the partial reception segment, and sends it to the activation signal verification unit 34.

  The activation signal verification unit 34 detects the activation signal in the AC signal, determines the presence or absence of emergency information, and sends the determined result to the emergency information verification unit 35.

  The emergency information verification unit 35 extracts emergency information when determining the presence of emergency information, and determines the authenticator included in the emergency information by “time information verification” and “CRC verification (operator verification)”. When it is verified and it is determined that the message is transmitted from a legitimate business operator, information and a message included in the emergency information are sent to the warning generation unit 36.

  After determining whether there is emergency information, the warning generation unit 36 includes the emergency information in the emergency information transmitted through the broadcast wave only when both the “time information verification” and “CRC verification (operator verification)” results are correct. Display the contents of or give a warning by voice.

  Here, the emergency information verification unit 35 according to the present invention will be described in more detail with reference to FIG.

  The emergency information verification unit 35 includes an emergency information extraction unit 351, a verification time code generation unit 352, a verification random number sequence generation unit 353, and an authenticator verification unit 354.

  The verification random number sequence generation unit 353 includes a random number generation unit 3531 and a random number sequence bit position determination unit 3532.

  The authenticator verification unit 354 includes a CRC inspection unit 3541, an authentication information inspection unit 3542, and a time information inspection unit 3543.

  The emergency information extraction unit 351 extracts emergency information when determining the presence of emergency information via the activation signal verification unit 34, and sends the extracted emergency information to the authenticator verification unit 352. FIG. 6 shows an example in which the emergency information extraction unit 351 sends the extracted emergency information to the authenticator verification unit 354 via the verification time code generation unit 352 and the verification random number sequence generation unit 353.

  When there is emergency information to be extracted, the verification time code generation unit 352 generates a code in which the year, month, day, hour, minute, and second of the current time on the receiving device 3 side are arranged.

  The random number generation unit 3531 is a functional unit that creates a common random number sequence (pseudo-random number sequence) between transmission and reception (between the provider transmission device 1 and the reception device 3 of the present embodiment). For example, a common random number sequence is generated and held between transmission and reception using a pseudo-random number generator that is secure in cryptographic theory. Alternatively, instead of the random number generation unit, a random number sequence prepared in advance can be kept secret in common between transmission and reception. Therefore, this random number sequence is the same as the random number sequence stored by the operator. The random number sequence is stored in a secret place so that the user cannot easily access it.

  The random number sequence bit position determination unit 3532 has a function of specifying the bit position in the random number sequence from the time code generated by the verification time code generation unit 352 by a specific function f (t) that is secretly held in common between transmission and reception. Have. A verification random number sequence consisting of a predetermined number of bits can be specified from the bit position in the random number sequence determined from this specific function f (t).

  Here, the authentication random number sequence generated on the transmission side is generated using the time information on the transmission side, while the verification random number sequence generated on the reception side is generated using the time information on the reception side. Therefore, these authentication random number sequences and verification random number sequences may take different values even if they are extracted from a common random number sequence.

  Therefore, the random number sequence bit position determination unit 3532 assumes a predetermined time (for example, 2 minutes) as the difference between the time information on the transmission side and the time information on the reception side, and the random number sequence generation unit 353 for verification uses this difference. The number of random number sequences for verification corresponding to is extracted. In order to reduce the increase in the number of verification random number sequences, it is assumed that the time codes generated mutually between transmission and reception are generated by arranging the year, month, day, hour, minute (not including seconds) side by side, Alternatively, the predetermined time is set short in view of verification accuracy.

  Therefore, the verification random number sequence generation unit 353 receives a predetermined bit from a bit position in the random number sequence that is defined in advance between transmission and reception determined from the specific function f (t) by the reception time information when receiving emergency information. A plurality of verification random number sequences of several minutes are generated and sent to the authenticator verification unit 354, respectively. Here, it should be noted that the predetermined random number sequence and the specific function f (t) are common between transmission and reception.

  The authenticator verification unit 354 has a function of verifying the authenticator in the extracted emergency information obtained from the emergency information extraction unit 351. More specifically, the authenticator verification unit 354 performs code conversion on a predetermined authenticator in the emergency information by using the verification random number sequence generated by the verification random number sequence generation unit 353, and performs time related to the emergency information. Information, authentication information used to authenticate the operator transmitting the emergency information, and data including cyclic redundancy check information, and time information related to the emergency information, authentication used to authenticate the operator transmitting the emergency information Information and information on the cyclic redundancy check are extracted and checked.

  If the authenticator transmitted from the transmission side is generated by executing exclusive OR with the number of bits of both the authentication random number sequence and the data constituting the authenticator being aligned, emergency information verification is performed. The authenticator verification unit 354 in the unit restores the received authenticator by performing an exclusive OR with the random number sequence for verification. On the other hand, if the authenticator transmitted from the transmission side is encrypted using time information such as the transmission time or earthquake occurrence time when transmitting emergency information as key information, the authenticator verification in the emergency information verification unit The unit 354 restores the authenticator received using the reception time information when receiving the emergency information as the key information.

  The CRC checker 3541 performs a CRC check on the correctness of the received data (legitimate business operator).

  The authentication information checking unit 3542 checks whether or not the predetermined authentication information transmitted from the transmission side is correct.

  The time information inspecting unit 3543 inspects whether or not predetermined time information transmitted from the transmission side is correct.

  In the present embodiment, the authenticator verification unit 354 uses each of a plurality of verification random number sequences to extract the contents information from the authenticator in the extracted emergency information obtained from the emergency information extraction unit 351. Attempts to restore internal information in the authenticator. Specifically, authentication information (for example, a business defined by ARIB) defined in advance through a CRC check from a value (hereinafter referred to as an authenticator equivalent value) obtained for a certain verification random number sequence. Attempts to recover from the predetermined bit position. If at least one of the plurality of verification random number sequences cannot restore the authentication information, the verification fails. On the other hand, if at least one piece of authentication information can be restored, the first verification is regarded as successful, and “time information” is extracted from the internal information in the authenticator. If this extracted time information (current time on the sending side or earthquake occurrence time) is within a predetermined time (for example, 2 minutes) with respect to the current time on the receiving side, the second verification is considered successful, The business that transmitted the message determines that the business is permitted to transmit emergency information, and issues a warning by the warning generation unit 36 based on a message in the emergency information or a message having a further hierarchical structure. If the verification fails, it is determined that the operator is not permitted to transmit emergency information, and the receiving device 3 is returned to the emergency information message reception standby state.

  The operations of the provider transmission device 1 and the reception device 3 will be further described with reference to FIGS.

  Referring to FIG. 7, the business entity transmitter 1 arranges the year, month, day, hour, minute, and second of the transmission time (or current time) in which the emergency information is transmitted by the current time code generation unit 111. Code is generated (step S1).

  In step S <b> 2, the provider transmission device 1 generates and holds a random number sequence common between transmission and reception by the random number generation unit 1121.

  In step S3, the provider transmitting device 1 uses the random number bit position determining unit 1122 to generate the time code generated by the current time code generating unit 111 with a specific function f (t) that is secretly held in common between transmission and reception. To specify the bit position in the random number sequence.

  In step S <b> 4, the business entity transmitter 1 uses the authenticator generation unit 113 to generate an authenticator including “time information”, “authentication information”, and “CRC”.

  In step S5, the provider transmission device 1 sets the emergency information including the generated authenticator by using the emergency information setting unit 114 in the message information to be transmitted using the AC carrier and transmits the information.

  Referring to FIG. 8, when there is emergency information extracted by the verification time code generation unit 352, the receiving device 3 (year), month, day, hour, minute of the current time on the receiving device 3 side. , A code in which seconds are arranged is generated (step S11).

  In step S12, the receiving device 3 uses the random number generation unit 3531 to create a common random number sequence (pseudo-random number sequence) between transmission and reception (between the provider transmitting device 1 and the receiving device 3 in this embodiment).

  In step S13, the reception device 3 uses the random function bit position determination unit 3532 to transmit time information (transmission time information or earthquake occurrence time) according to a specific function f (t) that is secretly held in common between transmission and reception. ) And the time information on the receiving side are specified as bit positions within a random number sequence for a predetermined time (for example, 2 minutes) assumed as a difference.

  In step S14, the receiving apparatus 3 generates a plurality of verification random number sequences by the verification random number sequence generation unit 353, and extracts an authenticator equivalent value using a value corresponding to a bit position in each random number sequence. To do.

  In step S15, the receiving device 3 checks whether the data received by the CRC checking unit 3541 is correct or not. If this check is successful, the process proceeds to step S16. If the CRC check fails, the receiving device 3 is again set to the emergency information. Return to the message reception standby state.

  In step S16, the receiving device 3 uses the authenticator verification unit 354 to attempt to restore the internal information in the authenticator using each of the plurality of verification random number sequences, and for a certain verification random number sequence. If one piece of pre-defined authentication information (for example, an operator code specified by ARIB) obtained through CRC check from the obtained authenticator equivalent value is found, the first verification is successful, and further authentication is performed. “Time information” is extracted from the internal information in the child, and this extracted time information (current time on the transmission side or earthquake occurrence time) is a predetermined time (for example, 2 minutes) with respect to the current time on the reception side. ), The second verification is considered successful. Only when all the verifications are successful, the operator that transmitted the message determines that the operator is permitted to transmit the emergency information, and proceeds to step S17. If the verification fails, the receiver 3 is again connected. Return to the emergency information message reception standby state.

  In step S <b> 17, when the receiving apparatus 3 determines that all verifications have succeeded and the provider that transmitted the message is a provider permitted to transmit emergency information, the warning generation unit 36 generates a warning. To do.

  FIG. 9 schematically shows an authentication and verification operation between the provider transmission device 1 and the reception device 3. Both the provider transmitting device 1 and the receiving device 3 have a common random number sequence (in the example, 5 digit authentication random number sequence 105 / verification random number sequence 106 is selected) and common functions f (t) 101, 102 have. This explains the case where the time information on the transmitting side (transmission time information) matches the time information on the verifying side, but more reliable verification is possible even if there is a gap between these times. As described above. An authentication code is generated from the authentication random number sequence 105 and authentication information (for example, earthquake occurrence time or business operator code) (103 in the figure) and transmitted as a message. The receiving side receives the message, extracts and verifies the authenticator using the verification random number sequence 106 (104 in the figure), and issues a warning if the verification is successful.

  As described above, the transmission system of this embodiment has an excellent effect. For example, for a one-segment service transmitted to an unspecified number of users, the transmission time information and the reception time are only required if the transmission device provider side and the reception device provider side store the random number sequence in a secret manner. Since the emergency information can be prevented from being reused due to the deviation of the information from the above-described permissible range for a predetermined time, only a predetermined operator can provide or verify the true emergency information.

  That is, only a business operator that stores a specific random number sequence can create valid authentication data. In addition, since the random number to be used changes according to the time information, the same authentication or verification information cannot be used a plurality of times, and is safe against replay attacks.

  In the above-described embodiment, in order to facilitate understanding of the present invention, the case where there is a deviation in the allowable range of time information between the transmission side and the reception side is illustrated, but between the transmission side and the reception side. In order to be able to match the time information, the provider transmission device 1 configured as described above can be configured to periodically provide the current time information to the reception device 1 configured as described above. . In this case, when there is no emergency information activation signal, the receiving side can obtain it while maintaining confidentiality after verifying it in the same manner as the operation of the above embodiment. The time of the receiving device 3 can be automatically set using the acquired time information of the current time, or the user can arbitrarily set the current time.

  Furthermore, in the above-described embodiment, the difference in time information used for authentication / verification between the transmission side and the reception side is described as a predetermined time (for example, 2 minutes), but the current time used for authentication / verification between the transmission side and the reception side. If the information shift is T1 and the time shift relative to the current time on the receiving device side is T2, the time information shift used for authentication / verification between the transmitting side and the receiving side is a predetermined time T1 + T2. Therefore, on the receiving device 3 side, by setting the predetermined time T1 + T2 (T1 = 0 when there is no deviation in the current time) as a threshold value at the time of authentication, the processing time and the emergency information verification determination accuracy can be improved. The balance can be arbitrarily selected.

  In the above-described embodiment, an example in which, on the transmission side, when generating an authenticator using the authentication random number sequence 105 and authentication information or the like (for example, earthquake occurrence time or operator code), code conversion is performed to generate the authentication code. did. This is to increase the confidentiality of the authenticator. Here, when generating an authenticator by executing exclusive OR by aligning the number of bits of both the authentication random number sequence 105 and authentication information (for example, earthquake occurrence time and operator code), the receiving side In addition, it is possible to restore and verify the information in the authenticator by executing exclusive OR, thereby reducing the calculation burden on the receiving side and processing at high speed.

  On the other hand, various methods can be applied to encrypt the authenticator. For example, the authenticator can be encrypted using a common key encryption method such as AES (Advanced Encryption Standard).

  In the above embodiment, when generating an authenticator on the transmission side, an example has been described in which an authentication random number sequence is generated at the current time (time of transmission) and an earthquake occurrence time is included in the authenticator. Instead of including the earthquake occurrence time in the authenticator, it can be configured to include the current time and the current time and the earthquake occurrence time It can also be configured to include both.

  As another embodiment, the transmission side separates the “time information” of the current time on the transmission side and the “message” on the transmission side in the AC signal separately from the “authenticator” shown in FIG. In addition to verifying the “authenticator” in the same manner as in the previous embodiment, the difference between the separately transmitted “time information” and the current time on the receiving side is within a predetermined time (for example, 2 minutes). It can be configured to check whether or not. In this case, if the result of the “authentication” inspection and the separately transmitted “time information” inspection are valid, a separately transmitted “message” is displayed or a warning sound is issued. Can be configured.

  According to the above-described embodiment and its modification, after identifying the “activation signal” from the received broadcast wave, it is possible to perform verification by time information and verification of the operator by a random number sequence. Even if an unsuccessful business operator sends an automatic startup message without permission, it is possible for the receiving device 3 not to accept automatic startup, and as a result, it is possible to prevent a business operator who abuses highly urgent information. .

  Although the specific embodiment has been described as a representative example of the above-described embodiment, many variations and substitutions can be made within the spirit and scope of the present invention. Accordingly, the invention should not be construed as limited by the embodiments described above, but only by the claims.

  The receiving device and the transmitting device according to the present invention enable quick and reliable transmission of emergency earthquake early warning, and can confirm that the emergency information of the authorized operator is received on the receiving side. It is useful for the use of the transmission system which transmits emergency information using a signal.

DESCRIPTION OF SYMBOLS 1 Provider transmission apparatus 2 Repeater 3, 3-1, 3-2, 3-3 Reception apparatus 11 Emergency information generation part 12 Error correction encoding part 13 Remultiplexing part 14 Modulation part
31 Antenna 32 RF Reception Unit 33 Signal Extraction Unit 34 Activation Signal Verification Unit 35 Emergency Information Verification Unit 36 Warning Generation Unit 105 Random Number Sequence for Authentication 106 Random Number Sequence for Verification 111 Current Time Code Generation Unit 112 Random Number Sequence Generation Unit for Authentication 113 Authentication Code Generation unit 114 Emergency information setting unit 351 Emergency information extraction unit 352 Verification time code generation unit 353 Verification random number sequence generation unit 354 Authentication code verification unit 1121 Random number generation unit 1122 Random number sequence bit position determination unit 1131 Time information setting unit 1132 Authentication information setting Unit 1133 CRC generation unit 3531 random number generation unit 3532 random number bit position determination unit 3541 CRC inspection unit 3542 authentication information inspection unit 3543 time information inspection unit

Claims (13)

A transmission device for transmitting emergency information by a transmission control signal of a terrestrial digital television broadcast wave,
Emergency information generating means for generating telegram information including an activation signal for identifying the presence or absence of emergency information and the emergency information;
Emergency information transmission means for transmitting the electronic message information by a transmission control signal of a terrestrial digital television broadcast wave,
The emergency information generating means includes
Means for selecting and generating a random number sequence for authentication determined by transmission time information when transmitting the emergency information from a predefined random number sequence;
Means for generating an authenticator by code-converting data including time information related to the emergency information, authentication information used for authentication of a carrier transmitting the emergency information, and information on cyclic redundancy check, using the authentication random number sequence When,
Means for including the authenticator in emergency information;
A transmission device comprising:   The authentication random number sequence is composed of a predetermined number of bits from a bit position in the predetermined random number sequence determined from a specific function according to transmission time information when transmitting the emergency information. Item 2. The transmission device according to Item 1.   The transmission apparatus according to claim 2, wherein the predetermined random number sequence and the specific function are common between transmission and reception.   The said authenticator is produced | generated by aligning the bit number of both the said random number sequence for authentication and the data which comprise the said authenticator, and performing an exclusive OR, The characterized by the above-mentioned. The transmission device according to any one of the above. The said authenticator is encrypted using the time information of the transmission time or earthquake occurrence time when transmitting the emergency information as key information. Transmitter device.   6. The transmission apparatus according to claim 1, wherein the time information related to the emergency information includes an earthquake occurrence time or a transmission time distributed from the Japan Meteorological Agency. A receiving device that receives emergency information by a transmission control signal of a terrestrial digital television broadcast wave,
Signal extraction means for extracting message information including an activation signal for identifying the presence or absence of emergency information and the emergency information from the transmission control signal;
Activation signal verification means for verifying the presence or absence of the emergency information from the activation signal;
An emergency information verification means for verifying the emergency information when the emergency information is present,
The emergency information verification means includes
Means for selecting and generating a plurality of verification random number sequences determined by a time lag between the reception time information when receiving the emergency information and the assumed transmission time information from a predetermined random number sequence;
By using the plurality of verification random number sequences, a pre-specified authenticator in the emergency information is transcoded, time information related to the emergency information, authentication information used for authentication of an operator transmitting the emergency information, and cyclic redundancy Means for restoring data including examination information;
Means for extracting and inspecting time information related to the emergency information, authentication information used for authentication of a company transmitting the emergency information, and information on the cyclic redundancy check;
A receiving apparatus comprising:   When the emergency information verification means determines that the time information related to the emergency information, the authentication information used for authentication of the operator transmitting the emergency information, and the information of the cyclic redundancy check are valid, respectively, The receiving device according to claim 7, further comprising warning generation means for issuing a warning about the emergency information.   The verification random number sequence is composed of a predetermined number of bits from a bit position in the predetermined random number sequence determined from a specific function according to reception time information when receiving the emergency information, The transmission device according to claim 7 or 8.   The receiving apparatus according to claim 9, wherein the predetermined random number sequence and the specific function are common between transmission and reception. The authenticator may align the number both of the bits of data constituting the random number sequence and the authenticator for authentication by performing an exclusive are generated, the emergency information verification unit, the verification random number characterized in that by performing an exclusive by train restoring the authenticator, the receiving apparatus according to any one of claims 7-10. The authenticator is the is encrypted as the key information the time information of the transmission time or earthquake occurrence time when transmitting emergency information, the emergency information verification unit, reception time information when receiving the emergency information the characterized by restoring the authenticator as key information, the receiving apparatus according to any one of claims 7-10.   The receiving device according to any one of claims 7 to 12, wherein the time information related to the emergency information includes an earthquake occurrence time or a transmission time distributed from the Japan Meteorological Agency.

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