WO2018016015A1

WO2018016015A1 - Spreading code generation device, spreading code generation program, and spreading code generation method

Info

Publication number: WO2018016015A1
Application number: PCT/JP2016/071203
Authority: WO
Inventors: 亨反町
Original assignee: 三菱電機株式会社
Priority date: 2016-07-20
Filing date: 2016-07-20
Publication date: 2018-01-25
Also published as: JPWO2018016015A1

Abstract

This spreading code generation device (100) generates a spreading code (15) used in communications. A default value arithmetic unit (10) which serves as a counter unit (91) generates a plurality of increment values by incrementing the default value (11) a plurality of times as a counter. A spreading code generation unit (20) which serves as an encryption unit (92) generates the spreading code (15) from each increment value by encrypting each increment value using an encryption algorithm that uses a secret key (13).

Description

Spread code generation apparatus, spread code generation program, and spread code generation method

The present invention relates to a spread code generation device, a spread code generation program, and a spread code generation method.

In recent years, various services using satellite communication and wireless communication have been provided. In these services, spread spectrum technology is often used to achieve communication connectivity and confidentiality. Spread spectrum systems are roughly classified into direct spread systems and frequency hopping systems. The direct spreading method spreads energy over a wider frequency than the transmission data itself. In the frequency hopping method, the frequency is switched at high speed according to a certain rule, and communication is performed between the transceivers.

In the direct spreading method, by using a code sequence, it can be expected that the signal to be transmitted has a characteristic such that it spreads over a wide band and looks like noise. This characteristic makes it difficult to intercept a signal to be transmitted, improves jamming resistance, and prevents interference with narrowband signals. Therefore, the direct spreading code plays an important role in order to realize reliable and safe transmission that does not cause interference with other signals.

In the direct spreading method generally used, communication connectivity is improved by using a spreading code sequence having a short periodicity. However, by observing a sequence to be communicated for a certain period, there is a high possibility that a spreading code sequence being used is estimated, and there is a problem regarding confidentiality.

It is necessary to increase confidentiality in order to increase resistance from jamming radio waves. For this reason, it is conceivable to use a sequence with a long period for the spreading code sequence of the direct spreading scheme, or to use a highly confidential code sequence using secret information that cannot be predicted by a third party. .

A configuration for enhancing the confidentiality of the spread code is disclosed as a conventional technique. Patent Document 1 discloses a method using a chaotic sequence as a means for improving confidentiality.
Patent Document 1 proposes a method of generating a chaotic spreading code having autocorrelation characteristics and cross-correlation characteristics suitable for satellite navigation systems and CDMA (Code Division Multiple Access) communication systems. Patent Document 1 states that confidentiality is improved as compared with a conventional spreading code.
However, regarding the secrecy of the spreading code based on the chaotic sequence, randomness indicating pseudo-randomness is shown, but strict security using an analysis technique of a general encryption technique is not shown. In addition, in order to perform spread spectrum communication using a highly confidential spreading code, it is necessary to establish synchronization of chaotic sequences. However, Patent Document 1 does not show effective means for establishing synchronization.

Also, Patent Documents 2 to 7 disclose a method for improving confidentiality using a chaotic sequence, but no effective means for establishing synchronization of the chaotic sequence is shown.

JP 2010-511336 Gazette JP-A-9-186630 JP-A-11-266179 JP 2000-252751 A JP 2001-292129 A JP 2002-290274 A JP 2007-96815 A

As described above, in order to increase the confidentiality of the spread code scheme, it is common to lengthen the cycle of the spread code sequence or use secret information that cannot be predicted by a third party in the spread code sequence. . As an example, conventionally, a method using a chaotic sequence has been proposed.

In a communication system of the prior art, that is, a communication system using a spreading code sequence using a chaotic sequence, it is difficult to search the entire code and to establish synchronization by increasing the secrecy and increasing the period. Become.

In order to establish synchronization efficiently, a method using a spread code sequence for actual data transmission and a pilot sequence for synchronization acquisition has also been proposed.

As an example, in the case of CSK (Code Shift Keying) modulation in which information is put on the phase of a spread code, it is necessary to acquire a reference timing using a pilot sequence in order to calculate a phase shift amount when performing demodulation. Therefore, in a highly confidential spreading code sequence using a chaotic sequence or a feedback shift register having a long register size, the receiving side of the communication system derives a spreading code sequence after a certain period of time (after t time). Dedicated calculation function and a derivation time for deriving a spread code sequence after a certain period of time are required.

An object of the present invention is to provide a spreading code generation method that does not require a dedicated calculation function and a derivation time for deriving a spreading code sequence after a certain period of time.

The spreading code generator of the present invention
In a spread code generation device that generates a spread code used for communication,
A counter unit that generates a plurality of increment values in which the initial value is incremented by incrementing the initial value as a counter multiple times;
And an encryption unit that generates a spreading code from each increment value by encrypting each increment value with an encryption algorithm using a secret key.

Since the spread code generation apparatus of the present invention includes the initial value calculation unit and the spread code generation unit, a spread code that does not require a dedicated calculation function for deriving a spread code sequence after a lapse of a fixed time and a derivation time. A generation device can be provided.

FIG. 3 is a diagram of the first embodiment, showing a configuration of a spread code generating apparatus 100. FIG. 3 is a diagram for explaining spreading code 15 in the first embodiment. FIG. 3 is a flowchart for explaining the operation outline of the spread code generating apparatus 100 in the first embodiment. The figure of Embodiment 1 is a figure explaining the initial value after time t. The figure of Embodiment 1 is a figure which shows the structure with which the spreading code production | generation part 20 is provided with CTR mode part 21A. FIG. 3 is a diagram illustrating the general CTR mode in the first embodiment. FIG. 6 is a diagram of the first embodiment, showing a spreading code system of a comparative example with respect to FIG. The figure of Embodiment 1 is a figure which shows the modification 1. FIG. The figure of Embodiment 1 is a figure which shows the modification 2. FIG. FIG. 9 is a diagram of the first embodiment and illustrates a third modification. FIG. 3 shows the processing circuit 99 in the first embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the part which is the same or it corresponds in each figure. In the description of the embodiments, the description of the same or corresponding parts will be omitted or simplified as appropriate.

Embodiment 1 FIG.
*** Explanation of configuration ***
A spreading code generating apparatus 100 according to the first embodiment will be described with reference to FIGS.
FIG. 1 is a diagram illustrating the configuration of the spread code generating apparatus 100. The spread code generating apparatus 100 is a computer. The spread code generating apparatus 100 includes hardware such as a processor 910, a storage device 920, and an input interface 930 (hereinafter referred to as an input IF 930). The storage device 920 includes an auxiliary storage device 921 and a memory 922. The spreading code generation device 100 includes, as functional configurations, an initial value calculation unit 10 that is a counter unit 91, a spreading code generation unit 20 that is an encryption unit 92, an acquisition unit 30, and an output unit 40.

In the following description, the functions of the initial value calculation unit 10, the spread code generation unit 20, the acquisition unit 30, and the output unit 40 in the spread code generation apparatus 100 are referred to as “part functions” of the spread code generation apparatus 100. . The “function of unit” of the spread code generating apparatus 100 is realized by software.

The auxiliary storage device 921 stores a program 14 for realizing the “function of part”. The program 14 is loaded into the memory 922, read into the processor 910, and executed by the processor 910. The auxiliary storage device 921 also stores an OS (Operating System). At least a part of the OS is loaded into the memory 922, and the processor 910 executes a program that realizes the “function of the unit” while executing the OS.

The input IF 930 is a port through which data is input. The input IF 930 may be a port connected to an input device such as a mouse, a keyboard, or a touch panel. Specifically, the input IF 930 is a USB (Universal / Serial / Bus) terminal. The input IF 930 may be a port connected to a LAN (Local / Area / Network).

The spreading code sequence will be briefly described. Hereinafter, the spreading code sequence is referred to as spreading code 15.
FIG. 2 is a diagram for explaining the spread code 15. FIG. 2A shows data that is spread by the direct spreading method. FIG. 2B shows the spread code 15. (C) of FIG. 2 is an XOR (exclusive or) of the data of (a) and the spread code 15 of (b). As shown in FIG. 2, the data is spread to a wide frequency by XOR with the spread code 15.

*** Outline of operation of spreading code generating apparatus 100 ***
An outline of the operation of the spread code generating apparatus 100 will be described with reference to FIG.
FIG. 3 is a flowchart showing an outline of the operation of the spread code generating apparatus 100.
In step S01, the input IF 930 receives as input data an initial value 11 for generating the spread code 15, a communication start time 12, and a secret key 13 that is secret information. Detailed description of the initial value 11 and the like will be described later. The acquisition unit 30 of the processor 910 stores the initial value 11 and the like input to the input IF 930 in the auxiliary storage device 921.

In step S02, the acquisition unit 30 loads the initial value 11, the start time 12, and the secret key 13 stored in the auxiliary storage device 921 into the memory 922. The acquisition unit 30 reads the initial value 11 and the like from the memory 922, transmits the initial value 11 and the start time 12 to the initial value calculation unit 10, and transmits the secret key 13 to the spreading code generation unit 20.

In step S03, the initial value calculation unit 10 generates an “initial value after time t” from the received initial value 11. The “initial value after time t” will be described below.

The initial value calculation unit 10 generates a plurality of increment values obtained by incrementing the initial value 11 by incrementing the initial value 11 a plurality of times using the initial value 11 as a counter. Hereinafter, the initial value 11 is also expressed as CTR. The increment value is CTR + i described later. The initial value calculation unit 10 increments CTR by 1 bit.
If CTR is 64-bit data (0, 0, ..., 0, 0) with all bits 0,
CTR + 1: (0, 0 ... 0, 1),
CTR + 2: (0, 0 ... 1,0),
CTR + 3: (0, 0 ... 1, 1),
...
CTR + (2 ⁶⁴ -1): (1,1 ... 1,1),
CTR + 2 ⁶⁴ : (0, 0 ... 0, 0),
It is.
Therefore, when CTR is a certain value of nbit,
CTR + 2 ⁿ returns to CTR.
CTR + 1 to CTR + 2 ⁿ are CTR + i (i = 1, 2, 3... 2 ⁿ )
May be written.

FIG. 4 is a diagram for explaining the “initial value after time t”. In FIG. 4, simple numerical values are used for explanation. The horizontal axis is time. The start time 12 indicates the communication start time. The time zone for communication is 1 second. In a communication system in which the spread code generating apparatus 100 is used, time Δt is set. In the case of FIG. 4, Δt = 100 μsec.
If the time zone of communication is one second, △ t is ^four 10. The time Δt is a partial time zone of 1 second, which is a communication time zone. The partial time zone is a time zone in which the communication time zone is divided.
An “initial value” is required for each Δt.
The first Δt is CTR + 1,
The second Δt is CTR + 2,
...
10 ⁴ −1 is CTR + (10 ⁴ −1),
10 ^4th is CTR + 10 ⁴ ,
Becomes the “initial value after time t”.
In particular,
CTR + 1 is an initial value after zero microseconds from the start time of 12,
CTR + 2 is the initial value after 100 μs from the start time of 12,
CTR + (10 ⁴ −1) is an initial value after “1 second−200 μsec”,
CTR + 10 ⁴ is the initial value after "1 seconds -100μ second".
As will be described later, the spread code generation unit 20 can generate the spread code 15 from the initial value (CTR + i) after each t time.

As shown in FIG. 4, each increment value (CTR + i) of the plurality of increment values corresponds to a plurality of different partial time zones included in the time zone in which communication is performed.

3, the spread code generation unit 20 receives the CTR + i that is the initial value after time t from the initial value calculation unit 10 and generates the spread code 15 using the CTR + i.

A case where the spread code generation unit 20 uses the CTR mode (Counter Mode) of the nbit block cipher algorithm will be described.
FIG. 5 shows a configuration in which the spread code generation unit 20 includes a CTR mode unit 21A that uses the CTR mode of the nbit block cipher algorithm.
FIG. 6 shows a general CTR mode. The CTR mode of the present embodiment corresponds to a portion indicated by a broken line frame 6 in FIG. That CTR mode portion 21A, which will be described later CTR mode portion 21B-j, CTR mode portion 21C-j, CTR mode unit 21D performs the encryption process _{E K} frame 6. The encrypted data E _K (CTR + i) corresponds to the spread code 15 and the plaintext block Mi corresponds to the data to be spread.

In the block cipher CTR mode, an nbit random data string can be generated by inputting an initial value as a counter (CTR) to a block cipher algorithm and inputting secret information as a secret key. Then, when CTR + 1 obtained by incrementing CTR by 1 bit is input to the block cipher algorithm, random data of the next different n bits can be generated.

When it is confirmed that the block cipher algorithm to be used is safe, in the case of the nbit block cipher, it is possible to generate nbit random data for increments of 2 ⁿ times. As shown in FIG. 5, the CTR that is the initial value 11 is nbit. The initial value calculation unit 10 increments CTR to generate CTR + i (i = 1, 2... 2 ⁿ ) and transmits it to the CTR mode unit 21A. The CTR mode unit 21A generates nbit random data by block encryption algorithm using CTR + i as input data. In FIG. 5, the n-bit spread code 15 is represented as <SCn>. An arrow from “CTR + 1” to <SCn> indicates that <SCn> is generated from CTR + 1. “CTR + 2 ⁿ is the same. The CTR mode unit 21A can generate the first <SCn> from CTR + 1, and similarly can generate <SCn> corresponding to CTR + ²ⁿ from CTR + 2. Therefore,“ nbit. × 2 ⁿ ”random data can be used as the spreading code 15.

As a general block encryption algorithm, an algorithm having a block size of 64 bits or 128 bits is currently used. In the CTR mode using these, it is possible to generate a highly confidential spreading code 15 having a period of ⁶⁴ bits × 2 ⁶⁴ = 2 ⁷⁰ or 128 bits × 2 ¹²⁸ = 2 ¹³⁵ .

In this way, in the spread code generation unit 20 that is the encryption unit 92, the CTR mode unit 21A encrypts each increment value with an encryption algorithm that uses a secret key, thereby generating a spread code from each increment value. .

Next, in step S05 of FIG. 3, the output unit 40 acquires the spread code 15 generated by the spread code generation unit 20, and outputs it as the spread code 15 for performing direct spreading in the communication system.

In FIG. 5, a specific configuration example of the spreading code generation unit 20 is shown, but the cycle (number of bits) of the spreading code depends on the block size of the block cipher algorithm employed in the CTR mode unit 21A of the spreading code generation unit 20. It is determined. That is, the number of bits of the spread code 15 obtained from one CTR + i is determined by the block size of the block cipher algorithm employed in the CTR mode unit 21A.

FIG. 7 is a diagram showing a spreading code system of a comparative example with respect to FIG. In the spreading code system of FIG. 7, in order to generate “initial value after time t”, a dedicated arithmetic function for generating “initial value after time t” is necessary. Since this dedicated calculation function uses a dedicated derivation logic, it has been necessary to spend considerable derivation time to generate the “initial value after time t”.
On the other hand, in this embodiment, in order to derive the “initial value after time t”, the initial value calculation unit 10 only needs to increment the CTR, so a dedicated calculation function is unnecessary. Furthermore, a synchronization acquisition function for acquiring synchronization and a pilot sequence for acquisition are unnecessary. In this embodiment, in order to synchronize communication, it is only necessary that the receiving apparatus can know the start time of communication. For this reason, the transmission apparatus may transmit communication start information indicating the communication start time to the reception apparatus. The start time 12 is an example of communication start information.
As described above, the spreading code generation apparatus 100 in FIG. 5 does not require the following (a), (b), and (c) that are required in the spreading code system of the comparative example in FIG.
(A) Dedicated calculation function for calculating “initial value after time t”;
(B) synchronization acquisition function;
(C) Pilot code sequence Even if the spreading code generation apparatus 100 does not include (a), (b), and (c), the safety of the entire system can be ensured.

Next, a modification of the CTR mode unit 21A in FIG. 5 will be described below. Modifications 1 to 3 described below are configurations of the spread code generation unit 20 when it is desired to further increase the period of the spread code 15 (when it is desired to increase the number of bits of the spread code 15).

<Modification 1>
FIG. 8 is a diagram illustrating a configuration of the spread code generation unit 20B of the first modification. The configuration of the initial value calculation unit 10 is the same as that in FIG.

The spreading code generator 20B has a plurality (J) of mbit block cipher algorithms. Each of the J encryption algorithms uses secret keys K1 to KJ as different secret information. That is, in the case of the spreading code generation unit 20B, J CTR mode units 21B-j (j = 1, 2,..., J) that perform processing of the mbit block cipher algorithm are provided. The CTR mode unit 21B-j uses the secret key Kj. The acquisition unit 30 reads the secret key Kj from the memory 922.

The CTR mode unit 21B-j executes the mbit block cipher algorithm with the secret key Kj using the CTR + i (i = 1, 2,...) Transmitted by the initial value calculation unit 10 as input data. That is, for each CTR + i, the J CTR mode units 21B-j perform the calculation.

In FIG. 8, the mbit spread code 15 is represented as <SCm>. As shown in FIG. 8, for CTR + 1, CTR mode unit 21B-1 to CTR mode unit 21B-J generate <SCm> 1 to <SCm> J, which are mbit spread codes 15, respectively. An arrow pointing from CTR + 1 to a frame surrounding <SCm> 1 to <SCm> J indicates that <SCm> 1 to <SCm> J are generated from CTR + 1. The same applies to CTR + 2 ^m . As a result, the connecting part 23 connects <SCm> 1 to <SCm> J, so that it is possible to generate the spread code 15 in which mbit × J are connected.
Next, for CTR + 2 in which CTR + 1 is incremented by 1 bit, CTR mode unit 21B-1 to CTR mode unit 21B-J generate the following different <SCm> 1 to <SCm> J.

When a method that has been confirmed to be safe is adopted as the block cipher algorithm used by the CTR mode unit 21B-j, as shown in FIG. 8, in the case of mbit block cipher, 2 ^m increments are added. , <SCm> 1 to <SCm> J can be generated.

8 is a case where the block cipher algorithm is used in parallel. Modification 1 is advantageous in terms of processing performance because J block cipher algorithms can be processed in parallel.

The CTR mode unit 21B-1 to CTR mode unit 21B-J are all sub-encryption units. As described above, each of the CTR mode unit 21B-1 to CTR mode unit 21B-J is an encryption algorithm using a secret key different from the secret key used in the other sub cipher unit, and other sub cipher units. A spreading code is generated from the same increment value by encrypting the same increment value.

<Modification 2>
Modification 2 will be described with reference to FIG.
FIG. 9 is a diagram illustrating a configuration of a spread code generation unit 20C according to the second modification. The configuration of the initial value calculation unit 10 is the same as that in FIG.

The spreading code generator 20C has a plurality (J) of mbit block cipher algorithms. Each of the J encryption algorithms uses secret keys K1 to KJ as different secret information. That is, the spreading code generation unit 20C includes J CTR mode units 21C-j (j = 1, 2,..., J) that perform processing of the mbit block cipher algorithm. The CTR mode unit 21C-j uses the secret key Kj. The acquisition unit 30 reads the secret key Kj from the memory 922.

First, the CTR mode unit 21C-1 performs an mbit block cipher algorithm calculation using the secret key K1 with CTR + 1 transmitted by the initial value calculation unit 10 as input data.

Next, the calculation result of the CTR mode unit 21C-1 is input to the CTR mode unit 21C-2. The CTR mode unit 21C-2 performs an mbit block cipher algorithm calculation using the secret key K2. Similarly, the CTR mode unit 21C-j (j = 3,..., J) receives the calculation result of the preceding CTR mode unit 21C- (j−1), and the CTR mode unit 21C-j The mbit block cipher algorithm is calculated using the secret key Kj.

As a result, as shown in FIG. 9, for CTR + 1, CTR mode unit 21C-1 to CTR mode unit 21C-J generate <SCm> 1 to <SCm> J, which are mbit spread codes 15, respectively. . An arrow pointing from CTR + 1 to a frame surrounding <SCm> 1 to <SCm> J indicates that <SCm> 1 to <SCm> J are generated from CTR + 1. The same applies to CTR + 2 ^m . When the connecting portion 23 connects <SCm> 1 to <SCm> J, it is possible to generate a spread code 15 in which mbit × J are connected. The same applies to CTR + 2 and later.

As in the first modification, when a scheme that is confirmed to be safe is adopted as the block cipher algorithm used by the CTR mode unit 21C-j, as shown in FIG. 9, in the case of the mbit block cipher, A spread code 15 of <SCm> 1 to <SCm> J can be generated for 2 ^m increments. That is, 2 ^m pieces of <SCm> 1 to <SCm> J can be generated.

The CTR mode unit 21C-1 to CTR mode unit 21C-J are all sub-encryption units. As described above, each of the CTR mode unit 21C-1 to CTR mode unit 21C-J is an encryption algorithm that uses a secret key different from the secret key used in other sub-encryption units when data is acquired. Then, by encrypting the acquired data, a spreading code is generated from the data. The CTR mode unit 21C-1 is a first sub-encryption unit 93 having the first connection order among the plurality of sub-encryption units. The CTR mode unit 21C-1, which is the first sub-encryption unit 93, acquires an increment value as data, encrypts the increment value, and generates a spread code 15 from the increment value. The sub cipher units (CTR mode units 21C-2, 21C-3... 21C-J) whose connection order is higher than that of the first sub cipher unit 93 are the sub cipher units immediately preceding the higher connection order as data. Is obtained, and the obtained spreading code is encrypted to generate a spreading code different from the obtained spreading code.

Modification 2 is a case where the block encryption algorithm is used in series. In the second modification, J block cipher algorithms cannot be processed in parallel. However, the data input to each block cipher algorithm is affected by the calculation result of the previous block cipher algorithm. Therefore, the modification 2 is a structure advantageous to safety.

In Modification 2, each of CTR mode unit 21C-1 to CTR mode unit 21C-J uses a different secret key, but the same secret key may be used. That is, it is most preferable that each CTR mode unit 21C-j uses a different secret key, but there may be a CTR mode unit 21C that uses the same secret key in the CTR mode unit 21C-j.

<Modification 3>
Modification 3 will be described with reference to FIG.
FIG. 10 is a diagram illustrating a configuration of the spread code generation unit 20D of the third modification. The configuration of the initial value calculation unit 10 is the same as that in FIG.

The spreading code generation unit 20 includes a CTR mode unit 21D and a key increment unit 22D. The CTR mode unit 21D has the same function as the CTR mode unit 21A. The key increment unit 22D increments the value of the secret key K by 1 bit, and generates an increment key Kj (j = 1, 2,..., J−1) in which the value is incremented.

The spread code generation unit 20D inputs the secret key K as secret information. The CTR mode unit 21D uses the secret key K to perform an mbit block encryption algorithm. As shown in FIG. 10, similarly to the CTR mode portion 21A of FIG. 5, CTR mode unit 21D uses the secret key K, from ^{CTR + 1 ~ CTR + 2 m} , a spreading code 15 of mbit, the ^{2 m} pieces <SCm> is generated. The arrow from CTR + 1 to <SCm> 1 indicates that <SCm> 1 was generated from CTR + 1. The same applies to CTR + 2 ^m .

After 2 ^m spreading codes 15 are generated with the secret key K, if further spreading codes 15 are required, the key increment unit 22D increments the secret key K by 1 bit to generate a secret key K + 1. The initial value calculation unit 10 again inputs CTR + 1 to CTR + 2 ^m to the CTR mode unit 21D. Similarly to the case where the secret key K is used, the CTR mode unit 21D uses the secret key K + 1 to generate 2 ^m <SCm>, which are mbit spread codes 15, from CTR + 1 to CTR + 2 ^m .

Thus, the key increment unit 22D increments the secret key K J−1 times, and the CTR mode unit 21D uses the secret key K + j (j = 1, 2,..., J−1) to CTR + 1 to CTR + 2 ^{From m} , 2 ^m <SCm> can be generated. In this case, as shown in FIG. 10, 2 ^m <SCm> can be generated for each secret key. Therefore, 2 ^m <SCm> can be generated.

Modified example 3 is a case where the value of the secret key K is counted up when the CTR uses all the cycles of the block cipher algorithm. In the third modification, it is not necessary to have a plurality of block cipher algorithms, and the data size of the secret information can be realized by the secret key size of the block cipher algorithm. For this reason, the modification 3 is a structure advantageous as a mounting size.

As described above, the CTR mode unit 21D encrypts each increment value (CTR + i) encrypted using the secret key K for the encryption algorithm by using an increment key such as the secret key K + 1 for the encryption algorithm. Thus, a spreading code is generated from each increment value.

Each of the CTR mode unit 21A, the CTR mode units 21B-1 to 21B-J, the CTR mode units 21C-1 to 21C-J, and the CTR mode unit 21D described in FIG. 5 and Modifications 1 to 3 described above. It has been confirmed that the cryptographic algorithm used in the CTR mode part is secure.

*** Effects of Embodiment 1 ***
(1) The spread code generating apparatus 100 includes an initial value calculation unit 10 that is a counter unit 91. The initial value calculation unit 10 increments CTR in order to derive CTR + i, which is an initial value after time t. That is, the initial value after time t is calculated by incrementing CTR. Therefore, the “dedicated calculation function for calculating the initial value after t time” which requires a lot of processing is unnecessary, and this time is shortened to the extent that the time required for calculating the “initial value after t time” is unnecessary. Become.
(2) Also, the transmission source device communicates communication start information such as a start start time such as 10 minutes later or a start start time such as 13:14:15 to the transmission destination device. Communication can be synchronized. Thus, synchronization can be achieved with simple processing.
(3) Since the spreading code generation apparatus 100 includes the initial value calculation unit 10 and the spreading code generation unit 20, a pilot code sequence is unnecessary.
(4) The long-period spread code 15 can be generated by the initial value calculation unit 10 and the spread code generation unit 20, and the encryption algorithm that has been confirmed to be safe can be used. High spreading codes can be generated.

*** Other configurations ***
FIG. 11 is a diagram showing the processing circuit 99. In the present embodiment, the “part function” of the spreading code generation apparatus 100 is realized by software, but as a modification, the spreading code generation apparatus 100 “function of part” may be realized by hardware. That is, the processing circuit 99 implements the “function of the unit” of the spreading code generation device 100 shown as the processor 910 and the function of the storage device 920. The processing circuit 99 is connected to the signal line 99a.
The processing circuit 99 is a dedicated electronic circuit that realizes the “function of the unit” of the spreading code generation apparatus 100 and the function of the storage device 920. Specifically, the processing circuit 99 includes a single circuit, a composite circuit, a programmed processor, a processor programmed in parallel, a logic IC, a GA (Gate Array), an ASIC (Application Specific Integrated Circuit), or FPGA (Field-Programmable / Gate / Array).

The spreading code generation apparatus 100 may include a plurality of processing circuits that replace the processing circuit 99. By these plural processing circuits, the “function of unit” of the spread code generating apparatus 100 is realized as a whole. Each processing circuit, like the processing circuit 99, is a dedicated electronic circuit.

As another modification, the function of the spread code generating apparatus 100 may be realized by a combination of software and hardware. In other words, some functions of the spread code generating apparatus 100 may be realized by dedicated hardware, and the remaining functions may be realized by software.

The processor 910, the storage device 920, and the processing circuit 99 are collectively referred to as a “processing circuit”. That is, the “unit function” and the storage device 920 of the spread code generating apparatus 100 are realized by a processing circuit.

“Part” may be read as “Process”, “Procedure” or “Process”. Further, the function of “unit” may be realized by firmware. That is, the operation of the spread code generation apparatus 100 can be grasped as a spread code generation program and a spread code generation method. Further, the “function of part” can also be realized as a recording medium and a program product for storing a spread code generation program.

In the first embodiment described above, when the CTR is ⁿ bits, the spread code is generated from 2 ⁿ increment values CTR + 1 to CTR + ²ⁿ obtained from 2 ⁿ increments. In this case, CTR + 2 ⁿ returns to the value of CTR.
Except for the above case, CTR (initial value) that does not increment may be used instead of CTR + 2 ⁿ . in this case,
CTR, CTR + 1, CTR + 2. . . Since CTR + (2 ⁿ −1), the number of increments is “2 ⁿ −1” (times).
The above contents are the same when the CTR is m bits.

As mentioned above, although Embodiment 1 of this invention was demonstrated, the content demonstrated in Embodiment 1 may be implemented partially, or may be implemented in combination. In addition, this invention is not limited to Embodiment 1, A various change is possible as needed.

7 dedicated calculation function, 8 spreading code generation function, 9 synchronization acquisition function, 10 initial value calculation unit, 11 initial value, 12 start time, 13 secret key, 14 program, 15 spreading code, 20, 20A, 20B, 20C, 20D Spreading code generation unit, 21A, 21B-1, 21B-2, 21B-J, 21C-1, 21C-2, 21C-J, 21D CTR mode unit, 22D key increment unit, 23 concatenation unit, 30 acquisition unit, 40 Output unit, 91 counter unit, 92 encryption unit, 93 first sub-encryption unit, 99 processing circuit, 99a signal line, 100 spreading code generation device, 910 processor, 920 storage device, 921 auxiliary storage device, 922 memory, 930 input IF.

Claims

In a spread code generation device that generates a spread code used for communication,
A counter unit that generates a plurality of increment values in which the initial value is incremented by incrementing the initial value as a counter multiple times;
A spreading code generation apparatus comprising: an encryption unit that generates a spreading code from each increment value by encrypting each increment value with an encryption algorithm using a secret key.
The increment value of each of the plurality of increment values is
The spreading code generation device according to claim 1, corresponding to a plurality of different partial time zones included in a time zone in which the communication is performed.
The cipher part includes a plurality of sub cipher parts,
Each of the sub cipher parts of the plurality of sub cipher parts is:
A spreading code is generated from the same increment value by encrypting the same increment value as that of the other sub-encryption unit with an encryption algorithm using a secret key different from the secret key used in the other sub-encryption unit The spreading code generation device according to claim 1 or 2.
The encryption unit includes a plurality of sub encryption units connected in series,
Each of the sub cipher parts of the plurality of sub cipher parts is:
When the data is acquired, an encryption algorithm using a secret key different from the secret key used in the other sub-encryption unit is used to generate a spreading code from the data by encrypting the acquired data,
The first sub-encryption unit having the first connection order among the plurality of sub-encryption units is:
The spread code is generated from the increment value by obtaining the increment value as the data and encrypting the increment value,
The sub cipher part having a lower connection order than the first sub cipher part is:
As the data, the spreading code generated by the sub-encryption unit immediately before the connection order is acquired, and the spreading code different from the acquired spreading code is generated by encrypting the acquired spreading code The spreading code generation device according to claim 1 or 2.
The encryption unit is
A key increment unit that increments the value of the secret key and generates an increment key in which the value is incremented;
The encryption unit is
A spreading code is generated from each increment value by encrypting each increment value encrypted using the secret key in the encryption algorithm by using the increment key in the encryption algorithm. The spreading code generation apparatus according to claim 1 or 2.
The cryptographic algorithm used in the cryptographic unit is:
The spreading code generation apparatus according to any one of claims 1 to 5, which is confirmed to be safe.
In a spread code generation device that is a computer that generates a spread code used for communication,
A process of generating a plurality of increment values in which the initial value is incremented by incrementing the initial value multiple times as a counter; and
A spreading code generation program for executing a process of generating a spreading code from each increment value by encrypting each increment value with an encryption algorithm using a secret key.
A spreading code generating device that generates a spreading code used for communication
By incrementing the initial value as a counter multiple times, a plurality of increment values in which the initial value is incremented are generated,
A spreading code generation method for generating a spreading code from each increment value by encrypting each increment value with an encryption algorithm using a secret key.