JP5315213B2 - Emergency information transmitter and receiver for digital terrestrial television broadcasting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmitter that transmits emergency information by transmission control signals of ground digital television broadcasting waves, and a receiver therefor. <P>SOLUTION: The transmitter includes an emergency information generating means 11 that generates telegram information including: a start signal for identifying presence or absence of the emergency information; and the emergency information. The emergency information generating means 11 includes: an authentication random number sequence generating portion 112 that determines from the predetermined random number sequence a portion of the time code for representing transmission time information in transmitting the emergency information as an encryption key so as to select and generate from the encryption key the authentication random number sequence determined by the predetermined function; an authentication code generating portion 113 that carries out code conversion of the data including the time information relating to the emergency information by the authentication random number sequence so as to generate the authentication code; and an emergency information setting portion 114 that sets the authentication code so as to be included in the emergency information. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to technology for transmitting and receiving emergency information in terrestrial digital television broadcasting, and more particularly to a transmission device and a reception device for quickly and accurately determining the validity of the content of emergency information.

  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 is not able to supply TMCC (Transmission and Multiplexing) when power is not supplied during normal operation of the receiving apparatus. Configuration Control: Transmission control) Received when the emergency alert broadcast activation flag is 1 (there is an emergency alert broadcast) by providing a reception function for the transmission control signal that detects the emergency alert broadcast activation flag stored in the carrier. By turning on the power of the device, it is possible 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 verifying the contents 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. Furthermore, it is desirable for the receiving apparatus to minimize the circuit configuration and the calculation load that are used only for receiving reliable emergency information. Here, the emergency information is a summary of information including emergency alert broadcasting and emergency earthquake warning (also referred to as earthquake motion warning).

  SUMMARY OF THE INVENTION An object of the present invention is to provide a transmission device and a reception device that minimize the circuit configuration and calculation burden for authentication when using a transmission system that transmits and receives emergency information in terrestrial digital television broadcasting.

  In order to achieve the above object, the present invention collates time information even in the transmission of emergency information using a limited number of bits (204 bits) of a transmission control signal (TMCC or AC signal), thereby making the reliability of emergency information reliable. Can be verified.

  In addition, among providers that provide services to an unspecified number of users, only a predetermined operator provides a transmitting device or a receiving device that enables transmission and reception of emergency information. The content of emergency information can be efficiently verified using a random number sequence kept secretly between the transmitting device and the receiving device.

That is, the transmission device of the present invention is a transmission device that transmits emergency information by a transmission control signal of a terrestrial digital television broadcast wave, and a telegram including an activation signal for identifying the presence or absence of emergency information and the emergency information. Emergency information generating means for generating information, and emergency information transmitting means for transmitting the telegram information by a transmission control signal of a digital terrestrial television broadcast wave, wherein the emergency information generating means provides time information regarding the emergency information in plain text. And means for generating an authenticator including the authenticator and means for including the authenticator in emergency information.

  Also, a transmission device that transmits emergency information using a transmission control signal of digital terrestrial television broadcast waves, and generates emergency information for generating telegram information including an activation signal for identifying the presence or absence of emergency information and the emergency information And emergency information transmission means for transmitting the telegram information by a transmission control signal of a digital terrestrial television broadcast wave, wherein the emergency information generation means transmits the emergency information from a predetermined random number sequence. A part of the time code representing the transmission time information of the mobile phone as an encryption key, and selecting and generating an authentication random number sequence determined by a specific function from the encryption key, and the authentication random number sequence, the emergency information And means for generating an authenticator by code-converting data including time information related to the time information, and means for setting the authenticator by including it in emergency information.

  Further, in the transmission device of the present invention, the bit value of the time code and the bit value of the data including time information related to the emergency information have the same number of bits, and the specific function includes a hash function, a pseudo-random number generator And any one of multidimensional polynomials, or one or more functions obtained by combining two or more of these.

  Further, in the transmitting device of the present invention, the authenticator obtained by code conversion converts the least significant bit for encryption key into a plaintext according to the value of the least significant bit for encryption key of the time code representing the transmission time information. It is generated as follows.

  Further, in the transmitting device of the present invention, the authenticator obtained by the code conversion uses a part or all of the lower bits including the least significant bit for the encryption key of the time code representing the transmission time information as plain text. It is generated.

  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, and the authenticator obtained by the code conversion has time information related to the emergency information. It is characterized by that.

  In the transmission apparatus of the present invention, the predetermined random number sequence, the specific function, and the key generation bit using a part of the time code 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

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 A verification unit, and a warning generation unit that issues a warning for the emergency information when the verification result is determined to be valid, and the received emergency information includes time information related to the emergency information in plain text. The urgent information verification unit includes a certifier, and the urgent information verification unit includes a unit that verifies the certifier including the time information related to the emergency information in plain text .

  Further, the receiving apparatus receives emergency information by a transmission control signal of a digital terrestrial television broadcast wave, and transmits an activation signal for identifying presence / absence of emergency information and telegram information including the emergency information from the transmission control signal. A signal extraction means for extracting; an 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; and A warning generating means for issuing a warning about the emergency information when it is determined that the result is valid, and the emergency information verification means at the time of receiving the emergency information from a predetermined random number sequence A part of a time code representing time information is determined as a decryption key, a means for generating a verification random number sequence determined by a specific function from the decryption key, and the verification random number sequence, It comprises means for transcoding a pre-defined authenticator in the emergency information, restoring data including time information relating to the emergency information, and means for examining data including time information relating to the emergency information. And

  In the receiving apparatus of the present invention, the bit value of the time code and the bit value of the data including time information related to the emergency information have the same number of bits, and the specific function includes a hash function, a pseudo-random number generator And any one of multidimensional polynomials, or one or more functions obtained by combining two or more of these.

  Also, in the receiving device of the present invention, the authenticator is generated with the least significant bit for the encryption key as a plaintext by the value of the least significant bit for the encryption key of a part of the time code representing the transmission time information. It is characterized by.

  Further, in the receiving device of the present invention, the authenticator is generated as a plaintext part or all of the lower bits including the least significant bit for encryption key of a part of the time code representing the transmission time information. Features.

  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, and the authenticator obtained by the code conversion has time information related to the emergency information. It is characterized by that.

  In the receiving apparatus of the present invention, the predetermined random number sequence, the specific function, and a key generation bit using a part of the time code are common between transmission and reception.

  Further, in the receiving apparatus of the present invention, the emergency information verification unit compares the bit values of the plaintext in the time code of the reception time information when determining the decryption key, and determines whether or not they match. If they match, the high-order bit of the time code with the bit value of the plaintext as the least significant bit is determined as the decryption key, and if the determination does not match, If the bit value one bit lower than the bit value of the plaintext is 0, the value used as the decryption key is decremented and determined as a new decryption key, and one bit lower than the bit value of the plaintext in the time code If the value of this bit is 1, the value used as the decryption key is incremented and determined as a new decryption key.

  According to the present invention, it is possible to verify the reliability of emergency information by collating time information.

  Further, by using a random number sequence that is secretly held in advance between the transmitting device and the receiving device of the business operator, only a specific business operator can create legitimate 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.

  Furthermore, according to the present invention, it is possible to authenticate emergency information transmitted with a small circuit configuration with a low delay and a certain error with respect to the time code between transmission and reception.

It is the schematic which shows the transmission system provided with the provider transmission apparatus and receiving apparatus of Example 1 by this invention. It is a figure which shows the provider transmission apparatus of Example 1 by this invention. It is a functional block diagram of the emergency information production | generation part in the provider transmission apparatus of Example 1 by this invention. It is the message | telegram information which shows an example in the AC signal transmitted in the provider transmission apparatus of Example 1 by this invention. It is a figure which shows the receiver of Example 1 by this invention. It is a functional block diagram of the emergency information verification part in the receiver of Example 1 by this invention. It is a flowchart which shows operation | movement of the provider transmission apparatus of Example 1 by this invention. It is a flowchart which shows operation | movement of the receiver of Example 1 by this invention. It is operation | movement explanatory drawing of the provider transmission apparatus and receiving apparatus of Example 1 by this invention. It is a schematic explanatory drawing of an example of operation | movement of the provider transmission apparatus and receiving apparatus of Example 1 by this invention. It is a flowchart showing the 1st verification technique of the authenticator in the receiver of Example 1 by this invention. It is a flowchart showing the 2nd verification technique of the authenticator in the receiver of Example 1 by this invention. It is explanatory drawing of the 3rd verification technique of the authenticator in the receiver of Example 1 by this invention. It is a flowchart showing the 3rd verification technique of the authenticator in the receiver of Example 1 by this invention. It is a figure which shows the specific example of the 3rd verification technique of the authenticator in the receiver of Example 1 by this invention. It is a functional block diagram of the emergency information production | generation part in the provider transmission apparatus of Example 2 by this invention. It is a functional block diagram of the emergency information verification part in the receiver of Example 2 by this invention.

  First, the provider transmission device 1 and the reception device 3 according to the first embodiment of the present invention will be described.

  FIG. 1 is a schematic diagram illustrating a transmission system including a provider transmission device 1 and a reception device 3 according to a first 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 provider transmission device 1 according to the first embodiment of the present invention. The provider transmission device 1 according to the first 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, error correction of about 8 bits is possible, so that the reliability of information is increased and more reliable transmission is possible.

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

  The provider transmission apparatus 1 according to the present embodiment uses the AC signal that is one of the transmission control signals to transmit the emergency information using the AC signal in the terrestrial digital television broadcast service that transmits the emergency information.

  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 illustrated in FIG. 4) for storing emergency information including information on breaking news is defined. Further, the error correction encoding unit 12 can apply an error correction code to the activation signal, the update flag, and the emergency information, and add a parity bit.

  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, , A random number sequence for authentication determined by transmission time information when transmitting emergency information is selected and generated, and is sent to the authenticator generation unit 113.

  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 1 and the reception device 3 of this 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 generator 1121, 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 identifying the bit position in the random number sequence from the time code generated by the current time code generation unit 111 by a specific function f (t) that is secretly held in common between transmission and reception. Have. Therefore, the authentication random number sequence is a predetermined number of bits from a bit position in a predetermined random number sequence determined from a specific function f (t) by transmission time information when transmitting emergency information, or This bit number can be generated by specifying another random number as a pointer. 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 may be used, but it is desirable to use a function that outputs a random value with respect to the input, such as a hash function, a pseudo-random number generator, or a multidimensional polynomial. Further, t in a specific function f (t) can be configured with a part of the time code of the transmission time information as an encryption key, which will be described in detail later.
(1) Hash function A hash function is a function that inputs an arbitrary bit string and compresses it into a fixed-length bit string. As hash functions, SHA-1, SHA-256, SHA-512, etc. are known (for example, “e-government recommended cipher list”, CRYPTREC <URL: http://www.cryptrec.go.jp/images /cryptrec_01.pdf>).
(2) Pseudorandom number generator The pseudorandom number generator is a function that receives secret information (seed) as input and generates pseudorandom numbers. MUGI, MULTI-S01, etc. are known as pseudorandom number generators (for example, “e-Government recommended cipher list”, CRYPTREC <URL: http://www.cryptrec.go.jp/images/cryptrec_01.pdf >reference).
(3) Multidimensional polynomial f (t) can be composed of a multidimensional polynomial that generates a pseudo-random sequence (random number sequence). For example, using a polynomial of f (t) = antn + an-1tn-1 +... + A1t + a0, a random sequence is generated for the time code t of the transmission time information, and the coefficients an, an-1,. .., A0 is secret information held between transmission and reception.

  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 stores data including “time information” related to the emergency information to be set, “authentication information” and “CRC (Cyclic Redundancy Check)” information used for authentication of the operator transmitting the emergency information. Then, the data of the authentication random number sequence and the number of both bits are aligned, an exclusive OR is executed to generate an authenticator, and it is sent to the emergency information setting unit 114. Further, the authenticator generation unit 113 performs transmission time information on the authenticator obtained by code-converting the data including the time information related to the emergency information by using the authentication random number sequence to generate the authenticator. Represents the position of the least significant bit for the encryption key as a plaintext (or a part or all of the lower bits including the position of the least significant bit for the encryption key) according to the value of the least significant bit for the encryption key of the time code representing It is effective to generate a final authenticator, which will be described in detail later.

  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 (x11 + x9 + 1) as the value Wk of the BPSK signal assigned to the SP signal of the carrier number k, similarly to the TMCC signal. For example, in the ISDB-T system In the case of an AC carrier (synchronous modulation unit in mode 3) in a partial reception segment (segment number # 0) of a terrestrial digital television broadcast wave, carrier numbers # 7, # 89, # 206, # 209, # 226, # 244, It is a value assigned to eight locations # 377 and # 407. Wk stored as the reference of the 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 Wk is 0, the odd frame is “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 Is. When Wk is 1, these are inverted. Thus, the “synchronization signal” is a signal having a known amplitude and phase.

  The “activation signal” for identifying the presence or absence of emergency information follows the “synchronization signal”. The “activation signal” is composed of 2 bits, “00” indicates “emergency information exists”, and “11” indicates “no emergency information”. Accordingly, the “activation signal” functions as a flag (start / end flag) indicating the start / end of transmission of emergency information (for example, earthquake motion warning information).

  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, the receiving device 3 according to the first embodiment of the present invention will be described.

  FIG. 5 is a schematic diagram of the receiving device 3 according to the first 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 receiving unit 32 receives a broadcast wave (radio frequency signal) transmitted from the provider transmission device 1 of the present 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 first embodiment of the present invention will be described in more detail with reference to FIG. FIG. 6 is a schematic diagram of the emergency information verification unit 35 in the receiving apparatus according to the first embodiment of the present invention.

  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 current time is detected from, for example, time setting by input of the receiving device, standard radio wave (radio clock, JJY), GPS, or TOT (Time Offset Table) included in the received signal of the received digital terrestrial broadcast wave. be able to. Alternatively, when the receiving device 3 is provided in a mobile phone, the current time can be detected by a signal from the base station.

  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 3531, 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. From the bit position in the random number sequence determined from the specific function f (t), for example, a verification random number sequence consisting of a predetermined number of bits can be specified. When the transmission side generates another random number with a predetermined number of bits as a pointer, a random number sequence for verification is generated by designating a random number sequence according to the same rule as that of the transmission side.

  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 time information shift between transmission and reception, and the verification random number sequence generation unit 353 uses the number of verifications corresponding to this shift. Each random number sequence 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. As another technique, the random number sequence bit position determination unit 3532 determines a part of a time code indicating reception time information when receiving emergency information as a decryption key t from a predetermined random number sequence, and performs the decryption. It is preferable that a random number sequence for verification determined by a specific function f (t) is selected from the key. This will be described in detail later.

  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 verification random number sequence consisting of several minutes is generated and sent to the authenticator verification unit 354. 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.

  Note that the authenticator verification unit 354 in the emergency information verification unit can use the exclusive OR by the random number sequence for verification as the reverse code conversion when the transmission side uses the exclusive OR as the code conversion. Then, the received authenticator is restored by executing exclusive OR as reverse code conversion.

  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. There is a technique for attempting to restore internal information in the authenticator (first and second verification techniques described later). 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.

  According to the first embodiment of 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. Further, according to the first embodiment of the present invention, even if it is determined that there is emergency information by receiving an emergency information activation signal from a received broadcast wave with a relatively simple configuration, time information verification and random number Since it can comprise so that a provider may be collated with a row | line | column, it can determine automatically that it is not emergency information provided from the regular provider.

  Here, the verification technique considering the time lag in both the provider transmission device 1 and the reception device 3 will be described in detail.

  As shown in FIG. 10, the transmission method of the first embodiment described above is further applied to a specific example. In FIG. 10, the provider transmission device 1 generates a time code of “transmission time information” by the current time code generation unit 111, and is generated based on the time code of the transmission time information by the authentication random number sequence generation unit 112. In this example, the authentication random number sequence is “secret information” (201 in the figure). The business entity transmitter 1 performs code conversion (for example, exclusive OR operation) using this secret information and a message (202 in the figure) including the time code of the transmission time information to generate an authenticator (in the figure). 203,204). The provider transmission device 1 transmits telegram information including an authenticator generated using an AC signal.

  On the other hand, the receiving device 3 generates a verification random number sequence generated based on the time code of the “reception time information” as “secret information” by the verification time code generation unit 352 (205 in the figure), and generates an AC signal. The authentication code is extracted from the received message information (206 in the figure). Using this secret information and the extracted authenticator, the receiving device 3 performs reverse code conversion (for example, exclusive OR operation) corresponding to the transmission side, and extracts a message including the time code of the transmission time information. (Illustrated 208). The receiving device 3 collates the time code of the extracted transmission time information with the time code of the reception time information by the authenticator verification unit 354, and if it matches, the received information is approved. Is transmitted, and a warning is issued (209 in the figure).

  Note that when generating a random number sequence for authentication (verification random number sequence) from transmission time information (or reception time information) from a random number sequence, a random number sequence specified by transmission time information (or reception time information) is used. Instead, a random number sequence for authentication (random number for verification) is specified by specifying a random number sequence of predetermined bits from the random number sequence using one or more bits specified by transmission time information (or reception time information) as a pointer. Column). The pointer in this case is a part of “secret information” shared secretly between transmission and reception.

  Here, as in the example shown in FIG. 10, in the transmission method of transmitting emergency information such as the earthquake early warning using the AC signal of digital terrestrial television broadcasting, the receiving device 3 is used by the authenticator verification unit 354. There are several ways to verify whether the received emergency information is a signal provided by the original broadcaster. Note that the number of bits of the authenticator equivalent value to be encrypted matches the number of bits of the authentication random number sequence, and the authenticator is the exclusive logic of the authenticator equivalent value to be encrypted and the authentication random number sequence of the same number of bits. It is assumed that sign conversion is performed with the sum. Note that the authenticator to be encrypted can be only time information. For example, the “authenticator” in the message example of FIG. 4 is described as being encrypted from “earthquake occurrence time (or transmission time information)”, “authentication information / message”, and “CRC”. The authentication code to be encrypted may be only “transmission time information”, and other accompanying messages (such as “authentication information / message” and “CRC”) may be transmitted as plain text.

(First verification technique)
First, the first verification technique will be described. According to the present embodiment, each time code of the transmission time information or the reception time information is assumed to be a code in which (year), month, day, hour, minute, and second are arranged and expressed in units of seconds. To do. As illustrated in FIG. 11, the receiving device 3 uses the authenticator verification unit 354 to collate the extracted time code of the transmission time information with the time code of the reception time information (step S21) and match. If it does not match, the time code of the reception time information is changed and the process proceeds to step S22. Subsequently, the receiving device 3 uses the authenticator verification unit 354 to collate the extracted time code of the transmission time information with the changed time code of the reception time information (for example, add +1) (step S22). ), A warning is generated if they match, but if they do not match, the time code of the reception time information is changed and the process proceeds to step S23. Subsequently, the receiving device 3 uses the authenticator verification unit 354 to collate the extracted time code of the transmission time information with the changed time code of the reception time information (for example, add −1) (step 1). S23) A warning is generated if they match, but if they do not match, the emergency information reception standby state is restored, or the time code of the reception time information is further changed (+2 or- 2 is added) and the same processing is repeated.

  This first verification technique can be decoded when the transmission time information on the transmission side and the reception time information on the reception side are completely coincident with each other, in a manner in which comparison operations are sequentially performed for each predetermined bit. is there. However, in this method, while reliable verification is obtained, the determination as to whether or not the decoded signal is correct is repeated until it is determined that the correct signal is obtained, and the clock error between transmission and reception is large. In some cases, the time required for the determination becomes longer.

(Second verification technique)
Next, the second verification technique will be described. As another method in the case where the processing time in the first verification technique is a problem, as shown in FIG. 12, the reception time information corresponding to a time lag (acceptable range) assumed in advance between transmission and reception is shown. A time code is prepared, and a warning is generated when the time code matches, but when it does not match, the emergency information reception standby state is restored. For example, in the example shown in FIG. 12, the time code of the extracted transmission time information and the time code of the reception time information are collated (step S32), and the time code of the extracted transmission time information is added and changed, for example, −1. The collation with the time code of the received reception time information (step S31) and the collation of the extracted time code of the transmission time information with the time code of the reception time information changed by adding, for example, +1 (step S33) are performed in parallel. To process.

  This second verification technique is a method in which decoding can be performed when the transmission time information on the transmission side and the reception time information on the reception side completely match, and comparison operations are performed in parallel. However, with this method, while reliable verification is obtained, it is necessary to have a plurality of comparison circuits within the allowable error in parallel, and when trying to increase the time allowable error between transmission and reception, a large-scale parallel is required. A circuit is required.

(Third verification technique)
Next, the third verification technique will be described. The third verification technique can speed up the comparison operation between the transmission time information on the transmission side and the reception time information on the reception side and reduce the circuit scale, that is, the first and second verification techniques. Each of the disadvantages can be solved. Furthermore, the third verification technique can give a degree of freedom to the setting of the allowable range of the time lag between transmission and reception relatively easily.

  FIG. 13 shows an example of the third verification technique. FIG. 14 shows an operation flow of the third verification technique. The transmission time information and the reception time information are coded with a common number of bits, and in the example shown in FIG. 13, there are 16 bits that can be counted in seconds. FIG. 13A shows an example in which the provider transmission device 1 uses the current time code generation unit 111 to encode the transmission time information with 16 bits. In FIG. 13 (b), the business entity transmitter 1 uses the random number sequence bit position determination unit 3532 based on the upper 10 bits (B1 to B10) of the time code of the transmission time information (that is, t in f (t)). In this example, a random number sequence for authentication is designated, and a message is subjected to code conversion (for example, exclusive OR operation).

  Further, the business entity transmitter 1 uses the authenticator generation unit 113 as a plaintext with the least significant bit for encryption key (B10 in this example) out of the code (16 bits) of the authenticator once transcoded. An authenticator to be transmitted is generated (see FIG. 13C). The value of B10 in the plain text is used for the comparison operation between the transmission time information on the transmission side and the reception time information on the reception side.

  As shown in FIG. 13 (d), the receiving device 3 encodes the reception time information with 16 bits by the verification time code generation unit 352 as in the transmission side. Subsequently, when the receiving device 3 receives the transmitted AC signal and indicates that the activation signal is present, the receiving device 3 extracts the authenticator, and the authenticator verifying unit 354 causes the value of B10 ( That is, TX_B10) is compared with the value of B10 (that is, RX_B10) in the time code of the reception time information (step S41 shown in FIG. 14). If they match in step S41, the receiving device 3 is designated based on the upper 10 bits (B1 to B10) of the time code of the reception time information (that is, t at f (t) is used as a decryption key). The verification random number sequence is determined as a decryption key, and the message is subjected to inverse code conversion (for example, exclusive OR operation).

  On the other hand, if they do not match in step S41, the receiving apparatus 3 determines that the value (that is, RX_B11) one lower than B10 in the time code of the reception time information is “0” or “1”. (Step S42). Subsequently, the receiver 3 determines, by the authenticator verification unit 354, a value obtained by decrementing the time code (B1 to B10) of the reception time information (for example, adding −1) as a decryption key if RX_B11 = 0. If RX_B11 = 1, a value obtained by incrementing the time code (B1 to B10) of the reception time information (for example, 1 is added) is determined as the decryption key.

  With the decryption key determined in the operation flow shown in FIG. 14 (FIG. 13 (e)), the verification of the key information has already been completed, and the receiving device 3 uses the determined decryption key to transmit the authenticator The message in can be decrypted. Further, the allowable value for the time difference is the count value represented by B11 to B16.

  In order to clarify the third verification technique more clearly, a specific example will be described with reference to FIG. Referring to FIG. 15 (a), for example, when the transmission time information is 2009/4/7 9:30:29 and the reception time information is 2009/4/7 9:30:39. There is a 10 second gap. The time code of the transmission time information may be in any form as long as it is a countable code, but in this example, the transmission time information is April 7, 2009, 9:30:30 as a time code that can be counted in seconds. The second is represented by “0001 1101 0011 0100” (16 bits). Similarly, the reception time information represents 9:30:39 on April 7, 2009 as “0001 1101 0011 1111”. If the upper 10 bits of the time code of the transmission time information are the encryption key, the encryption key is “0001 1101 00”, and if the upper 10 bits of the time code of the reception time information is the decryption key, the decryption key is “0001 1101”. In order to authenticate whether or not the keys match each other, the receiving device 3 compares the authenticator bit (B10), which is a plaintext bit, with the receiving side key verification bit RX_B10. . In FIG. 15A, the transmission side key authentication bit TX_B10 and the reception side key verification bit RX_B10 are both “0”, and therefore the reception device 3 determines that the decryption key matches the encryption key. Judgment can be made.

  Next, referring to FIG. 15B, FIG. 15B shows a state after 6 seconds from the state of FIG. If the transmission time information is 9:30:35 on April 7, 2009 and the reception time information is 9:30:45 on April 7, 2009, there is a 10-second shift. The transmission time information is represented by “0001 1101 0011 1010” (16 bits) on April 7, 2009, 9:30:35, and the reception time information is “0001” on April 7, 2009, 9:30:45. 1101 0011 0101 "(16 bits). If the upper 10 bits of the time code of the transmission time information is an encryption key, the encryption key is “0001 1101 00”, and if the upper 10 bits of the time code of the reception time information is a decryption key, the decryption key at this time is In order to authenticate whether or not the keys match each other with “0001 1101 01”, the receiving device 3 uses the least significant bit (B10) of the encryption key, which is a plaintext bit, and the least significant bit of the decryption key. Compare bit (B10).

  In FIG. 15B, the transmission side key authentication bit TX_B10 and the reception side key verification bit RX_B10 do not match, and the next lower bit RX_B11 is “0”. The decryption key at this time is decremented (added by −1) to “0001 1101 01” to determine the decryption key “0001 1101 00” (see FIG. 15C). The determined decryption key matches the encryption key. In the above example, the time information at the time of reception is delayed by 10 seconds, but if it is advanced, the decryption key determined by following the operation flow of step S42 shown in FIG. 14 matches the encryption key. Will do.

  As described above, in the third verification technique, the number of bits of the message to be encrypted matches the number of bits of the authentication random number sequence generated from the time code, and the authenticator uses the same number of bits as the message for authentication. When the sign conversion is performed using the exclusive OR of the random number sequence, the reception device 3 compares the plaintext bit values at the predetermined bit positions in the time code of the reception time information to determine whether or not they match. If there is a match, if the bit value of the plaintext is the least significant bit, the upper bit of the time code of the reception time information is determined as the decryption key, and the determination does not match If the value of the next lower bit of the bit value of the plaintext in the time code of the reception time information is 0, the least significant bit of the time code of the reception time information having the bit value of the plaintext as the least significant bit Decrime If the value of the one lower bit of the plaintext bit value in the time code is 1, the value of the time code of the reception time information with the bit value of the plaintext as the least significant bit is determined. A value obtained by incrementing the least significant bit is determined as a decryption key.

  Here, in the third verification technique, an example of counting in seconds has been described, but it can be set to an arbitrary value such as a unit of 3 seconds, a unit of 10 seconds, a unit of 1 minute, or a unit of 2 minutes. It is only necessary that the time code and the time code of the reception time information are matched so as to be used in common between transmission and reception. Similarly, the number of high-order bits of the time code used for the encryption key and the decryption key may be matched so as to be used in common between transmission and reception. Furthermore, the bit position of the time code used for the encryption key and the decryption key is not necessarily used from the most significant bit of the time code.

  Furthermore, in the example described with reference to FIGS. 13 to 15, the provider transmitting device 1 uses the least significant bit for encryption key (B10 in this example) out of the code (16 bits) of the authenticator once code-converted. ) As plaintext and an authenticator to be finally transmitted is described. However, an authenticator to be finally transmitted with the lower-order bits (ie, B10 to B16) including the least significant bit for the encryption key as plaintext. Even if generated and transmitted, the same effect as described above can be obtained. Alternatively, some of the lower bits (that is, B10 to B16) may be plaintext. Also in this case, similarly to the above-described example, it is possible to compare the transmission time information on the transmission side and the reception time information on the reception side using the plaintext B10 value of the least significant bit for the encryption key. In other words, when the receiving device 3 receives the transmitted AC signal and indicates that the activation signal is present, the receiving device 3 extracts the authenticator, and the authenticator verifying unit 354 causes the value of B10 in the transmitted authenticator (that is, TX_B10) and the value of B10 in the time code of the reception time information (that is, RX_B10) are compared, and if they match, the upper 10 bits (B1 to B10) of the time code of the reception time information are (I.e., t in f (t) as a decryption key) is determined as a decryption key. If they do not match, the value of B11 in the time code of the reception time information (ie, RX_B11) The verification random number sequence incremented or decremented according to is determined as a decryption key.

  Further, referring to the message example of FIG. 4, the authenticator encrypted by the provider transmitting apparatus 1 is only “transmission time information”, and other accompanying messages (“authentication information / message”, “CRC”, etc.) Is transmitted as plain text, the receiving device 3 can be configured to verify the received “transmission time information” with the time code of the reception time information. In this case, the calculation cost of the receiving device 3 can be further reduced.

  To summarize each of the above-described embodiments, the provider transmission device 1 and the reception device 3 of each embodiment according to the present invention can be configured as follows.

  For example, the specific function may be one of a hash function, a pseudo-random number generator, a multidimensional polynomial, or may be composed of one or more functions obtained by combining two or more of these functions. .

  In addition, the authenticator obtained by code conversion can generate the position of the least significant bit for the encryption key as a plaintext based on the value of the least significant bit for the encryption key of a part of the time code representing the transmission time information. . Alternatively, the authenticator obtained by code conversion can also generate a part or all of the lower bits including the least significant bit for the encryption key of a part of the time code representing the transmission time information as plain text. At this time, a predetermined random number sequence, a specific function, and a bit for generating a key (encryption key / decryption key) using a part of a time code used between transmission and reception are common between transmission and reception.

  Further, the authentication random number sequence (or verification random number sequence) may be composed of a predetermined number of bits from a bit position in a predetermined random number sequence determined from a specific function f (t). In addition, it is configured to specify one bit at a time in a pointer sequence that is kept secret between transmission and reception, or to generate a random number sequence for authentication (or verification random number sequence) by specifying multiple bits (for example, 2 bits) at a time. Can be used.

  In addition to the above-described embodiments, the provider transmission device 1 and the reception device 3 of other embodiments according to the present invention can be configured.

  For example, an authentication random number sequence (or verification random number sequence) is generated from bit positions specified by a plurality of functions f (t), or a pointer sequence that is secretly held between these bit positions between transmission and reception is further separated. It can also be configured to specify a random number. Alternatively, an authentication random number sequence (or verification random number) specified by combining a plurality of pointer sequences so that another bit is specified by the second pointer sequence from the bits specified by the first pointer sequence. Column) can be generated and used.

  Therefore, the authentication random number sequence (or verification random number sequence) according to the present invention is designated by a predetermined number of bits from a bit position in a predetermined random number sequence determined by a specific function f (t). It can be a combination of one or more bit values.

  Alternatively, the authentication random number sequence in the present invention is one at one or a plurality of bit positions specified by a predetermined pointer sequence from a bit position in a predetermined random number sequence determined from a specific function f (t). It can be a combination of the above bit values. In this case, the predetermined pointer string can be a single pointer string or a combination of a plurality of pointer strings. Thereby, secrecy can be improved with a relatively simple configuration by keeping secret between transmission and reception.

  As described above, in generating the authentication random number sequence (or verification random number sequence), various modes for enhancing the secrecy can be considered. However, in any of these aspects, an authentication random number sequence (or verification random number sequence) determined by a time code at the current time is generated or held for a random number that is secretly held in common between transmission and reception. As a result, it is possible to prevent the emergency information from being reused due to a deviation of the transmission time information and the reception time information that exceeds a predetermined time within the allowable range described above.

  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, as long as the sender's provider and the receiver's provider store the random number sequence secretly, the transmission time information and the reception time information Therefore, it is possible to prevent the emergency information from being reused by the deviation of the above-described allowable range beyond the predetermined time, so that 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 time information used for authentication / verification between the transmission side and the reception side is described as a predetermined time (for example, 2 minutes). However, the transmission time and information between the transmission side and the reception side are described. If the time lag of the set time is T1, and the time lag between the internal set time on the receiving device side and the absolute current time is T2, the time information used for authentication / verification on the transmitting side and the receiving side is The predetermined time T1 + T2. Therefore, on the receiving device 3 side, this predetermined time T1 + T2 (if each device is operating at the correct current time on both the transmitting side and the receiving side, only a difference T1 between the transmission time and the reception time occurs, and T2 = 0, but when the difference T1 between the transmission time and the reception time is equal to or less than the minimum unit of the time code, T1 = T2 = 0) is set as the threshold value at the time of authentication, and the processing time It is also possible to arbitrarily select the balance of the accuracy of the emergency information verification judgment.

  In the above embodiment, referring to FIG. 9, when code conversion is performed using exclusive OR, the sender side uses the authentication random number sequence 105 and authentication information (for example, the earthquake occurrence time and the operator code). In order to increase confidentiality when generating an authenticator, the number of bits of both the authentication random number sequence 105 and the authentication information (for example, the earthquake occurrence time and the operator code) are aligned to perform exclusive OR. It has been explained that it can be configured to execute and generate an authenticator. In the case of this configuration, the receiving side can also execute exclusive OR to restore and verify the information in the authenticator, reducing the calculation burden on the receiving side and processing at high speed.

  In the above embodiment, referring to FIG. 9, when code conversion is performed using an encryption method, on the transmission side, a random number sequence 105 for authentication, authentication information, etc. (for example, earthquake occurrence time or operator code) When generating an authenticator, the authenticator is encrypted using a common key cryptosystem with the authentication random number sequence 105 as key information, and the received authenticator is decrypted using the verification random number sequence 106. It has been explained that it can be configured. In the case of this configuration, the load is greater than the configuration in which the above-described exclusive OR is executed to generate an authenticator, but the secrecy can be further improved.

  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.

  Next, the provider transmission device 1 and the reception device 3 according to the second embodiment of the present invention will be described. The same components as those in the first embodiment will be described with the same reference numerals.

  The block diagram of the provider transmission device 1 according to the second embodiment is the same as the provider transmission device 1 according to the first embodiment (see FIG. 2). However, the provider transmission device 1 according to the second embodiment is different only in the configuration of the emergency information generation unit 11. FIG. 16 shows a functional block diagram of the emergency information generator 11 of the second embodiment. The emergency information generation unit 11 includes a current time code generation unit 111, an authenticator generation unit 113, and an emergency information setting unit 114. The emergency information generation unit 11 according to the second embodiment is different from the emergency information generation unit 11 according to the first embodiment in that the authentication random number generation unit 112 is not provided.

  The authenticator generation unit 113 uses the time information setting unit 1131 to set “time information” including “earthquake occurrence time” or “current time” as information in the “authenticator” in the transmitted message information. Further, the authentication information setting unit 1132 sets “authentication information” that can include, for example, a message of emergency information generated by a business operator as information in the “authenticator” in the message information to be transmitted. Then, the CRC generating unit 1133 adds a CRC code to “time information” and “authentication information”, and sets the information as “authenticator” in the transmitted message information.

  The authenticator generation unit 113 stores data including “time information” related to the emergency information to be set, “authentication information” and “CRC (Cyclic Redundancy Check)” information used for authentication of the operator transmitting the emergency information. It is sent to the emergency information setting unit 114 as an authenticator.

  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.

  As described above, the operator transmission device 1 according to the first embodiment generates an emergency information by code-converting the authenticator using the authentication random number sequence, and generates emergency information including the code-converted authenticator as AC carrier. In contrast, the emergency information generation unit 11 according to the second embodiment transmits emergency information including an authenticator in plain text using an AC carrier.

  Next, the receiving device 3 according to the second embodiment will be described. The block diagram of the receiving device 3 according to the second embodiment is the same as the receiving device 3 according to the first embodiment (see FIG. 5). However, the receiving device 3 of the second embodiment is different only in the configuration of the emergency information verification unit 35. The functional block diagram of the emergency information verification part 35 of Example 2 is shown in FIG. The emergency information verification unit 35 includes an emergency information extraction unit 351, a verification time code generation unit 352, and an authenticator verification unit 354. The emergency information verification unit 35 according to the second embodiment is different from the emergency information verification unit 35 according to the first embodiment in that the verification random number sequence generation unit 353 is not provided.

  The authenticator verification unit 354 uses the CRC checking unit 3541 to perform a CRC check on whether the received data (legitimate business operator) is correct. Further, the authentication information inspection unit 3542 checks whether the authentication information transmitted from the transmission side is correct, and the time information inspection unit 3543 checks whether the time information transmitted from the transmission side is correct. Do.

  As described above, the receiving device 3 of the first embodiment generates a verification random number sequence and verifies the authenticator, whereas the receiving device 3 of the second embodiment compares the plaintext authenticator with time information and the operator. To verify.

  In the description of the above embodiment, it is assumed that the information of the emergency bulletin is transmitted by the AC signal in the partial reception segment (segment number # 0) of the ISDB-T terrestrial digital television broadcast wave. Yes. Many mobile / mobile terminals such as mobile phones receive this partial reception segment (segment number # 0) and watch programs (one-segment service). Therefore, the receiving device 3 according to each embodiment of the present invention provided in a mobile phone or the like can receive an AC signal for transmitting information on emergency breaking news. On the other hand, also in the receiver 3 of each embodiment of the present invention provided in a digital TV for fixed reception that receives other segments, the emergency signal is received by receiving the AC signal in the partial reception segment. Can receive information.

  According to the above-described embodiment and its modification, after identifying the “activation signal” from the received broadcast wave, it is possible to perform collation based on time information and collation of business operators. As a result, even if an unauthorized business operator sends an automatic activation message without permission, it is possible for the receiving device 3 not to accept automatic activation. It becomes possible to prevent.

  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 201 Confidential information 202 Message 203 Code conversion processing unit 204 Authenticator 205 Secret information 206 Authenticator 207 Reverse code conversion processing unit 208 Message 209 Verification of transmission time information and reception time information 351 Urgent 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 Sequence Bit Position Determination Unit 3541 C C inspection section 3542 authentication information checking unit 3543 time information inspection section

Claims (16)

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 generates means for generating an authenticator including the time information related to the emergency information in plain text ;
Means for including the authenticator in emergency information;
A transmission device comprising: 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
A part of a time code representing transmission time information when transmitting the emergency information is determined as an encryption key from a predetermined random number sequence, and an authentication random number sequence determined by a specific function is selected from the encryption key. Means for generating;
Means for generating an authenticator by code-converting data including time information related to the emergency information by the authentication random number sequence;
Means for including the authenticator in emergency information;
A transmission device comprising:   The bit value of the time code and the bit value of data including time information related to the emergency information are composed of the same number of bits, and the specific function is any one of a hash function, a pseudo random number generator, and a multidimensional polynomial The transmission apparatus according to claim 2, wherein the transmission apparatus is one or a combination of two or more functions.   The authenticator obtained by the code conversion is characterized in that the least significant bit for encryption key is generated as a plaintext by the value of the least significant bit for encryption key of a part of the time code representing the transmission time information. The transmission device according to claim 3.   The authenticator obtained by the code conversion is generated as a part of or all of the lower bits including the least significant bit for the encryption key of the time code representing the transmission time information as plain text. The transmission device according to claim 3. 6. The key generation bit using the predetermined random number sequence, the specific function, and a part of the time code is common between transmission and reception, according to claim 2. The transmitting device described. 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, It is characterized by the above-mentioned. The transmission device according to any one of the above. The time information related to the emergency information includes an earthquake occurrence time or a transmission time distributed from the Japan Meteorological Agency, and the authenticator includes time information related to the emergency information. The transmitter according to the item. 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;
Warning generation means for issuing a warning about the emergency information when it is determined that the verification result is valid,
The emergency information to be received includes an authenticator that includes time information related to the emergency information in plain text,
The said emergency information verification means has a means to verify the authenticator which contains the time information regarding the said emergency information as plaintext, The receiving apparatus characterized by the above-mentioned. 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;
Warning generation means for issuing a warning about the emergency information when it is determined that the verification result is valid,
The emergency information verification means includes
A part of a time code representing reception time information when receiving the emergency information is determined as a decryption key from a predetermined random number sequence, and a verification random number sequence determined by a specific function is selected from the decryption key Means to generate
Means for transcoding a pre-defined authenticator in the emergency information with the verification random number sequence and restoring data including time information relating to the emergency information;
Means for inspecting data including time information relating to the emergency information;
A receiving apparatus comprising:   The bit value of the time code and the bit value of data including time information related to the emergency information are composed of the same number of bits, and the specific function is any one of a hash function, a pseudo random number generator, and a multidimensional polynomial The receiving apparatus according to claim 10, wherein the receiving apparatus includes one or more functions obtained by combining two or more of them.   The position of the least significant bit for encryption key is generated as plaintext by the value of the least significant bit for encryption key of a part of a time code representing the transmission time information. 11. The receiving device according to 11.   The said authenticator is produced | generated as a plaintext part or all of the low-order bits including the least significant bit for encryption keys of a part of time code showing the said transmission time information. Receiver. 14. The key generation bit using the predetermined random number sequence, the specific function, and a part of the time code is common between transmission and reception, according to any one of claims 10 to 13, The receiving device described. When the emergency information verification means determines the decryption key,
  Of the time code of the reception time information, the plaintext bit values are compared to determine whether they match, and if they match, the time when the plaintext bit value is the least significant bit If the upper bit of the code is determined as the decryption key and the determination does not match, and the value of the bit lower than the bit value of the plaintext in the time code is 0, the value used as the decryption key Is decremented as a new decryption key, and if the value of the bit one bit lower than the bit value of the plaintext in the time code is 1, the value used as the decryption key is incremented to be used as a new decryption key The receiving device according to claim 10, wherein the receiving device is determined. The time information related to the emergency information includes an earthquake occurrence time or a transmission time distributed from the Japan Meteorological Agency, and the authenticator includes time information related to the emergency information. The receiving device according to item.

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