JPH0772793A - Secret data distributing device - Google Patents

Abstract

PURPOSE:To provide the secret data distributing device which can distribute secret data with a small amount of information. CONSTITUTION:This device is equipped with a secret data generating device 1 which generates 1st secret data with a unidirectional function (f), 2nd secret data with a unidirectional function (g), and 3rd secret data with an amalgamation function (h), a secret data transmitting means 3 which transmits (i)th 1st secret data Vi and (j)th 2nd secret data Vj at a request for (i)th-(j)th 3rd secret data, and a secret data reproducing device 2 which reproduces 1st secret data after the (i)th data from 1st secret data Ui with the unidirectional function (f), 2nd secret data before (j)th data from 2nd secret data Vj with the unidirectional function (g), and (i)th-(j)th 3rd secret data with the amalgamation function (h).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a user with information necessary for a secret data generator to generate a plurality of secret data and reproduce all or a part of the secret data in response to a request from the user. The present invention relates to a secret data delivery device that delivers the requested secret data from the delivered information to the user.

[0002]

2. Description of the Related Art In recent years, with the downsizing, price reduction and high performance of information processing devices, magazines and books that were conventionally recorded and distributed on paper are converted into electronic data, The data is stored in a data storage medium and distributed, or distributed by data communication via a network, and the user converts the distributed electronic data into characters and images by using an information processing device, and the magazine or book You can enjoy the contents. At this time, if the electronic data may be leaked to a third party other than the creator and the user, it may cause copyright infringement, and it may be difficult for the creator to receive a reasonable payment for valuable information. Therefore, it is necessary to prevent such a thing. For this purpose, the usual method is to disturb (encrypt) the electronic data in a specific way, and distribute the method of restoring the disturbance (called a decryption key) to users by means other than electronic data. However, the user uses the decryption key to restore the encrypted electronic data to the original state. Here, the decryption key is kept secret except for the creator and the user so that a third party does not know the content of the electronic data.

The decryption key in the above specific example is a kind of secret data. Regarding this secret data, the secret data generator generates a large number of secret data, and all of the secret data are requested at the request of the user. Alternatively, a secret data delivery device that delivers the information necessary for reproducing a part to the user and reproduces the requested secret data from the delivered information is required for the user. FIG. 6 shows the configuration of a conventional example of such a secret data delivery device.

In FIG. 6, reference numeral 40 is a secret data generating device, 41 is a secret data reproducing device, and 42 is a secret data transmitting means.

First, in the secret data generation device 40,
Reference numeral 50 is a secret data generation unit that generates secret data.
The secret data is numbered by a positive integer number i and is represented by Si. When m is a positive integer representing the number of secret data, the secret data generating unit 50 calculates S1, S
2 ,. , Sm are created. Here, each secret data Si is completely random binary data. Here, the number of bits of the binary data is a value that should be determined according to the usage form of the secret data. For example, when the secret data is a typical block cipher secret key, it becomes 64-bit binary data. 5
A secret data storage unit 1 stores the secret data generated by the secret data generation unit 50. The secret data Si is the number i
Can be used as an index. This secret data Si is used, for example, as an encryption key for the record with the number i. 52 is a secret which reads out the secret data stored in the secret data storage unit 51 and which has the number notified by the secret data request information transmitting means 57 described later, and outputs it to the secret data reproduction information transmitting means 58 described later. This is a data reading unit. Reference numeral 53 is a first control unit that controls the operations of the secret data generation unit 50, the secret data storage unit 51, and the secret data reading unit 52 described above.

Next, in the secret data reproducing device 41,
Reference numeral 54 denotes a secret data request information creation unit that creates request information that specifies necessary one of the secret data stored in the secret data storage unit 51. In the following description, it is assumed that the operator specifies the necessary secret data numbers (plurality). 55 is designated by the secret data request information creation unit 54 via the secret data request information transmission unit 57, taken out from the secret data storage unit 51 by the secret data reading unit 52, and transmitted by the secret data reproduction information transmission unit 58. It is a secret data reproduction value storage unit for storing a reproduction value. The secret data reproduction value Si stored in this way is used as a decryption key for the record of the number i, for example. 56
Is a second control unit that controls the operations of the secret data request information creation unit 54 and the secret data reproduction value storage unit 55 described above.

In the secret data transmission means 42, 5
Reference numeral 7 is a secret data request information transmitting means for transmitting the request information created by the secret data request information creating unit 54 to the secret data reading unit 52. As a specific example of the secret data request information transmitting means 57, a personal computer communication device attached to the secret data reproducing device 41 accesses the personal computer communication device attached to the secret data generating device 40, and the secret data request information is in the form of a code. There is a way to transmit. As another specific example, there is a method in which the operator of the secret data reproducing device 41 calls the operator of the secret data generating device 40 and conveys the secret data request information in words. Reference numeral 58 is a secret data reproduction information transmission means for transmitting the secret data selected by the secret data reading section 52 to the secret data reproduction device 41. As a specific example of the secret data reproduction information transmission means 58, the secret data generation device 40
The personal computer communication device associated with the secret data reproducing device 41
There is a method of accessing the personal computer communication device attached to the and transmitting the confidential data information in the form of a code. As another specific example, there is a method in which the operator of the secret data generation device 40 conveys the secret data information in words to the operator of the secret data reproduction device 41 by telephone.

An example of processing in the conventional secret data delivery apparatus as described above will be described below.

Now, the secret data generation device 40 generates and stores 52 pieces of secret data, of which the number is 14
Data from 26 to 26 shall be delivered to the user.
In such a situation, for example, an electronic information magazine is published every week, each issue is encrypted with a different encryption key, and only the user who has the decryption key for the encryption key can read the contents of that magazine. If you are able to read, read from April to June (weeks 14 to 26)
This occurs when the decryption key (secret data) is delivered to a weekly subscriber. (Secret data generation) The first control unit 53 of the secret data generation device 40 sets the content of the register M (not shown) to 52,
The content of the register I (not shown) is set to 1, and the secret data generation unit 50 is activated. At this time, the secret data generation unit 50 generates the secret data S1 which is a random number. This secret data S1 is stored at address 1 of the secret data storage unit 51. Subsequently, the first control unit 53 increments the content of the register I by 1, the secret data generation unit 50 is activated, and the next secret data S2 is generated. This secret data S2 is stored in address 2 of the secret data storage unit 51. The above process is repeated until the content I of the register exceeds the content (52) of the register M. (Request for secret data) On the other hand, the operator operating the secret data reproducing device 41 is the secret data request information creation unit 5
4 is instructed to create the information indicating that the secret data from S14 to S26 is taken out from the secret data generating device 40. At this time, the registers S and E (not shown) in the secret data reproducing device 41 have 14 and 26 respectively.
Is stored. Here, as a specific example of the secret data request information, notification is made by the head number and the last number of the secret data to be requested. This secret data request information is sent to the secret data reading unit 52 via the secret data request information transmitting means 57. (Reading and Delivery of Secret Data) The secret data reading unit 52 receives the secret data request information from the secret data request information transmitting means 57 and extracts the numbers of the requested first and last secret data. In this case, the first number is 1.
4. Recognize that the final number is 26. After that, out of the secret data stored in the secret data storage unit 51, the secret data whose address is the number in the above range is taken out. The secret data extracted in this way is separated by a delimiter and arranged to form secret data reproduction information. In the present case, the secret data reproduction information is S14, S
15, S16 ,. ． (Omitted in the middle). ． It becomes like S25 and S26. Here, S14 to S26 are 64-bit binary data, and [,] is a delimiter. The secret data reproduction information created in this way is delivered to the secret data reproduction device 41 via the secret data reproduction information transmission means 58. (Storing of Secret Data) Next, the secret data reproduction information transmitted from the secret data reproduction information transmission means 58 is transferred from the area of the secret data reproduction value storage section 55 having the content (14) of the register S as an address to the register E. It is stored up to the area having the content (26) of as an address. The secret data reproduction value stored in this way is accessed by using the secret data number as an address, taken out of the secret data reproducing device 41, and used as a decryption key for encrypted data for various purposes.

[0010]

However, in the above-mentioned conventional secret data delivery device, since a plurality of secret data are independently generated, when delivering a plurality of secret data at the request of the user, There is no other way but to enumerate the secret data information, and there is a problem that the secret data information becomes long if the number of secret data increases. In the above example, it was necessary to list 12 pieces of 64-bit binary data. This is extremely inconvenient especially when the secret data reproduction information transmission means 58 is realized by a person performing it via a telephone or the like.

An object of the present invention is to provide a secret data delivery device capable of delivering secret data with a small amount of information in consideration of such problems of the conventional secret data delivery device.

[0012]

According to the present invention of claim 1, based on the head value U1 of the secret data, a one-way function f is used, and Uk + 1 = f ( Uk) and secret data generating means for generating secret data Uk, and secret data transmitting means for transmitting the i-th secret data Vi in response to a request for the i-th and predetermined predetermined secret data. And a secret data reproducing means for reproducing the predetermined secret data from the i-th secret data Vi by using the one-way function f based on the secret data Vi.

According to the second aspect of the present invention, m is a positive integer, the first secret data start value U1, the second secret data final value Vm, the first one-way function f, and the second secret data f. The first secret data Uk is generated by sequentially obtaining Uk + 1 = f (Uk) for an integer k of 1 or more and less than m, which has a one-way function g and a fusion function h. Vm-k = g (Vm-k
+1) are sequentially obtained to generate the second secret data Vm-k, and 1
Secret data generating means for generating third secret data by Sk = h (Uk, Vk) for an integer k not less than m and m, and i-th, j-th, and i-th to j-th Secret data transmission means for transmitting the i-th first secret data Vi and the j-th second secret data Vj in response to a request for a predetermined third secret data in between, and a first one-way function f, a second one-way function g, and a fusion function h, and Ui + k = f (Ui + k- for an integer k of 1 or more from the i-th first secret data Ui transmitted. 1) are sequentially calculated and the i-th
The first secret data after the th th is reproduced, and the transmitted j th data is transmitted.
Vj-k = g (Vj-k + 1) is sequentially obtained for the integer k of 1 or more from the second secret data Vj, and the second secret data before the j-th secret data is reproduced. The secret data delivery device is provided with secret data reproducing means for reproducing the third secret data by Sk = h (Uk, Vk) for the following integer k.

[0014]

According to the present invention, the secret data generating means sequentially uses the one-way function f based on the head value U1 of the secret data to sequentially generate Uk + 1 = f (Uk) for an integer k of 1 or more and less than m. The secret data Uk is obtained and the secret data transmission means uses the i-th
In response to the second and subsequent requests for the predetermined secret data, the i-th secret data Vi is transmitted, and the secret data reproducing means uses the one-way function f based on the secret data Vi to calculate the i-th secret data Vi. The secret data Vi of the predetermined number is reproduced from the secret data Vi.

Further, according to the present invention, the secret data generation means uses the integer k which is 1 or more and less than m from the first secret data head value U1.
, The first secret data Uk is generated by sequentially obtaining Uk + 1 = f (Uk), and Vm-k = g (Vm for the integer k of 1 or more and less than m from the second secret data final value Vm. -k + 1) is sequentially obtained to generate the second secret data Vm-k, and the third secret data is generated by Sk = h (Uk, Vk) for an integer k of 1 or more and m or less, The data transfer means receives the i-th first secret data Vi and the j-th secret data Vi for the request of the i-th, the j-th, and the predetermined third secret data between the i-th and the j-th. Of the transmitted i-th first secret data Ui from the transmitted i-th first secret data Ui, Ui + k = f
(Ui + k-1) are sequentially obtained to reproduce the first secret data after the i-th secret data, and Vj- for an integer k of 1 or more from the transmitted second secret data Vj of the j-th secret. k = g (Vj-k +
1) is sequentially obtained to reproduce the second secret data before the j-th, and Sk = h (Uk, V
Reproduce the third secret data by k).

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing its embodiments.

FIG. 1 is a block diagram of a secret data delivery device according to an embodiment of the present invention. That is, the secret data delivery device is composed of the secret data generating device 1, the secret data reproducing device 2, and the secret data transmitting means 3.

First, in the secret data reproducing device 1, 4
Is a first register for storing the first secret data start value U1 and 5 is a second register for storing the second secret data final value Vm. Here, m is a positive integer indicating the maximum number of secret data. The secret data is 64 bits, and each register stores 64-bit data.

Reference numeral 6 denotes a first function calculator which inputs the contents of the first register 4 and calculates the value of the first one-way function f, and updates the contents of the first register 4 to the calculated value. is there.
Here, the one-way function f is a function in which the function value y = f (x) can be easily calculated for a certain input value x, but the input value x corresponding thereto cannot be easily calculated from the function value y. . For example, in the block cipher of the American Data Encryption Standard (DES), a 64-bit input plaintext A is encrypted with a 64-bit key K to create a 64-bit ciphertext C. However, this input plaintext A is kept secret. A one-way function can be realized by setting the value as a value, the key K as the function input value x, and the ciphertext C as the function output value y. 7
Is a second function calculator that inputs the contents of the second register 5 and calculates the value of the second one-way function g, and updates the contents of the second register 5 to this calculated value. One-way function g
Can be realized by the above-mentioned block cipher. However, the secret plaintext value of the block cipher must be different between the functions f and g.

Numeral 8 indicates the contents of the first register 4 which are sequentially updated by U1, U2 ,. ． , Um are stored in the ascending order from the address number 1 and the secret data storage unit 9 stores the contents of the sequentially updated second register 5 in Vm, Vm-1 ,. ． , V1
The second secret data storage unit 10 stores the addresses in descending order from the address number m.
Of the first secret data Uk stored at the address k of the secret data storage unit 8 and the second secret data Vk stored at the address k of the second secret data storage unit 9 as input The third secret data Sk is calculated by calculating the value of h.
Is a first fusion function calculation unit for generating = h (Uk, Vk). Here, the fusion function h is a function for generating one output z from two inputs of x and y, and is a function in which the output z is affected by all bits of each input. An example of a fusion function is such that z is the bitwise exclusive OR of the inputs x and y.

Numeral 11 reads out the first secret data Ui from the first secret data storage unit 8 by the start request number i and the final request number j notified by the secret data request information transmitting means 13 which will be described later, and also 2 secret data storage unit 9
Is a secret data reading unit that reads out the second secret data Vj from and outputs the second secret data Vj to the secret data reproduction information transmitting means 14 described later. Reference numeral 12 is a first control unit that controls the operation of each unit of the above-mentioned 4 to 11 of the secret data generation device 1, and each of the above units 4 to 12 constitutes a secret data generation unit.

Next, in the secret data transmission means, 13
Is a secret data request information transmission means for transmitting information to the effect that the secret data reproducing device 2 requests the secret data generating device 1 for the third secret data from the i-th to the j-th and before, and 14 is the above request. On the other hand, the secret data generation device 1 is a secret data reproduction information transmission means for transmitting the i-th first secret data Ui and the j-th second secret data Vj to the secret data reproduction device 2. The secret data request information transmitting means 13 and the secret data reproduction information transmitting means 14 constitute the secret data transmitting means 3.

Next, in the secret data reproducing device 2, 1
5 is the instruction of the operator of the secret data reproducing device 2,
A secret data request information creation unit that creates secret data request information. Reference numeral 16 is a third register for storing the i-th first secret data Ui transmitted by the secret data reproduction information transmission means 14, and 17 is the j-th register transmitted by the secret data reproduction information transmission means 14. The fourth register 18 for storing the second secret data Vj receives the content of the third register 16 as an input, and stores the value of the first one-way function f similar to that of the first function calculator 6 described above. A third function calculator that calculates and updates the contents of the third register 16 to this calculated value, 19 receives the contents of the fourth register 17, and uses the same function as the second function calculator 7 described above. A fourth function calculator that calculates the value of the one-way function g of 2 and updates the contents of the fourth register 17 to this calculated value;
Contents of the register 16 of Ui, Ui + 1 ,. ． The first secret data reproduction value storage unit 21 stores the contents of the fourth register 17 which are sequentially updated as Vj, Vj-1. ． Is a second secret data reproduction value storage unit for storing in descending order from the address number j, and 22 is a first secret data reproduction value storage unit 20 for an integer k of i or more and j or less.
The first secret data reproduction value Uk stored at the address k of the second secret data reproduction value Vk and the second secret data reproduction value Vk stored at the address k of the second secret data reproduction value storage unit 21 are input. The value of the fusion function h similar to that of the first fusion function calculation unit 10 is calculated, and the third secret data reproduction value Sk = h
This is a second fusion function calculation unit that generates (Uk, Vk).
23 is a second for controlling the operation of each part of the above 15 to 22
Each of the above sections 15 to 23 constitutes a secret data reproducing means.

Next, the processing procedure of the secret data delivery device of the above embodiment will be described with reference to the drawings. (1. Creation of secret data) First, the secret data generation device 1
The first control unit 12 of the memory M stores an integer m indicating the number of secret data in the memory M (not shown) and an integer 1 in the memory I (not shown).
, The first secret data U1 in the first register 4, and the second
The second secret data Vm is set in the register 5 of the above. Hereinafter, the content of the memory M is represented by m, and the content of the memory I is represented by i.
Here, the integer m is a value indicating the number of secret data.

In FIG. 2A, the first control unit 12 checks whether or not mi is -1 (step S
If 1) or -1, the process ends. Otherwise,
The first control unit 12 transfers the content of the first register 4 to the area of the address i in the first secret data storage unit 8 (step S2). This corresponds to the first secret data Ui.

Next, the first control unit 12 copies the contents of the second register 5 to the address mi of the second secret data storage unit 9.
The data is transferred to the +1 area (step S3). This corresponds to the second secret data Vm-i + 1.

Next, the first controller 12 activates the first function calculator 6 to calculate the value of the first one-way function f which receives the contents of the first register 4 as input, The content of the register 4 of 1 is updated to this calculated value (step S4), and subsequently,
The first control unit 12 activates the second function calculation unit 7,
Second one-way function g with the contents of register 5 of
Is calculated, and the content of the second register 5 is updated to this calculated value (step S5).

Thereafter, the content of the memory I is incremented by 1 (step S6), and the process returns to step S1. (2. Use of secret data) In FIG. 2B, the first control unit 12 activates the first fusion function calculation unit 10 to store the first secret data for an integer k of 1 or more and m or less. The first secret data Uk stored at the address k of the unit 8;
The second secret data Vk stored at the address k of the second secret data storage unit 9 is input, the value of the fusion function h is calculated, and the third secret data Sk = h (Uk, Vk) is calculated. It is generated (step S11). This third secret data Sk
Is taken out of the secret data generation device 1 and is used as an encryption key for encrypting the kth record, for example. (3. Creation and Notification of Request Information) In FIG. 3A, the secret data request information creating unit 15 creates the secret data request information in accordance with an instruction from the operator of the secret data reproducing device 2 (step S21). Here, the secret data request information is the start number i and the end number j of the requested secret data number.
Will be notified. Further, the second control unit 23 stores i, j, j-i in memories I, J, N (not shown), respectively.
Stores the value of. In the following, the contents of the memories I, J and N are represented as i, j and n, respectively.

Next, the secret data request information is sent to the secret data generating device 1 via the secret data request information transmitting means 13.
Is notified (step S22), and the secret data reading unit 11 temporarily stores the start request number i and the final request number j notified by the secret data request information transmitting means 13 (step S23).

Thereafter, the secret data reading section 11 reads the first secret data Ui from the area of the first secret data storage section 8 at the address i, and also reads the first secret data Ui from the area of the second secret data storage section 9 at the address j. The second secret data Vj is read from (step S24), and each read secret data is sent to the secret data reproduction information transmission means 14. (4. Reproduction of the first secret data) In FIG.
The second control unit 23 of the secret data reproduction device 2 stores the i-th first secret data Ui transmitted by the secret data reproduction information transmission means 14 in the third register 16,
Further, the integer 1 is set in the memory K (not shown) (step S31). Hereinafter, the contents of the memory K will be represented as k. Further, the contents of the first secret data reproduction value storage unit 20 are cleared to zero.

Next, the second controller 23 checks whether the content of m-i-k is -2 (step S32),
If it is -2, the process ends. Otherwise, the second control unit 23 transfers the contents of the third register 16 to the area of the address i + k-1 of the first secret data reproduction value storage unit 20 (step S33). This corresponds to the first secret data reproduction value Ui + k-1.

Next, the second controller 23 activates the third function calculator 18 to calculate the value of the first one-way function f which receives the contents of the third register 16 as input, The contents of the register 16 of 3 are updated to this calculated value (step S3
4).

Thereafter, the content of the memory K is incremented by 1 (step S35), and the process returns to step S32. (5. Reproduction of second secret data) In FIG. 4 (a),
The second control unit 23 of the secret data reproducing device 2 stores the j-th second secret data Vj transmitted by the secret data reproducing information transmitting means 14 in the fourth register 17.
Further, the integer 1 is set in the memory K (not shown) (step S41). Hereinafter, the contents of the memory K will be represented as k. Further, the contents of the second secret data reproduction value storage unit 21 are cleared to zero.

Next, the second control section 23 checks whether the content of jk is -1 (step S42), and -1
If so, the process ends. Otherwise, the second control unit 23 transfers the contents of the fourth register 17 to the area of address j−k + 1 of the second secret data reproduction value storage unit 21 (step S43). This is the second secret data Vj-k +
Equivalent to 1.

Next, the second controller 23 activates the fourth function calculator 19 to calculate the value of the second one-way function g which receives the contents of the fourth register 17 as an input, The content of the register 17 of 4 is updated to this calculated value (step S4
4).

After that, the content of the memory K is incremented by 1 (step S45), and the process returns to step S42. (6. Use of secret data reproduction value) In FIG.
The second control unit 23 activates the second fusion function calculation unit 22, and the first k stored in the address k of the first secret data reproduction value storage unit 20 for the integer k of i or more and j or less. The secret data reproduction value Uk and the second secret data reproduction value Vk stored at the address k of the second secret data reproduction value storage unit 21 are input and the value of the fusion function h is calculated to calculate the third value.
The secret data reproduction value Sk = h (Uk, Vk) is generated (step S51). This third secret data reproduction value is taken out of the secret data reproduction device 2 and used as a decryption key for decrypting the kth record, for example.

Next, the above-mentioned processing procedure will be described using a specific example. (1. Creation of secret data) First, the secret data generation device 1
The first control unit 12 of the memory M stores an integer m in the memory M (not shown).
= 52, the integer 1 in the memory I (not shown), the first secret data u1 (64-bit binary data) in the first register 4, and the second secret data V52 in the second register 5.
(64-bit binary data) is set. Where the integer m
Is a value indicating the number of secret data.

Next, the first control unit 12 checks whether the content of mi is -1 (step S1). Since MI is now 51, the first controller 12 transfers the content u1 of the first register 4 to the area of address 1 of the first secret data storage 8 (step S2). This is the first
Of the secret data U1.

Next, the first control unit 12 sets the content v52 of the second register 5 to the address m of the second secret data storage unit 9.
Transfer to the area of -i + 1 = 52 (step S3). This corresponds to the second secret data V52.

Next, the first control unit 12 activates the first function calculation unit 6 and inputs the value of the first one-way function f which receives the content of the first register 4 as input u 2 (64-bit value). (Binary data) and updates the content of the first register 4 to this calculated value (step S4). Subsequently, the first controller 12 activates the second function calculator 7 and The value of the second one-way function g v51 (64-bit binary data), which receives the contents of the register 5 of the above, is calculated, and the contents of the second register 5 is updated to this calculated value (step S5).

Thereafter, the content of the memory I is incremented by 1 to 2 (step S6), and the process returns to step S1.

Then, the first controller 12 checks whether or not mi is -1 (step S1). m-
Since i is 50, the process proceeds to step S2.

Next, the first control unit 12 transfers the content u2 of the first register 4 to the address 2 of the first secret data storage unit 8.
To the area (step S2). This corresponds to the first secret data U2.

Next, the first control unit 12 transfers the content v51 of the second register 5 to the address m of the second secret data storage unit 9.
Transfer to the area of -i + 1 = 51 (step S3). This corresponds to the second secret data V51.

Next, the first control unit 12 activates the first function calculation unit 6 and inputs the value of the first one-way function f which receives the contents of the first register 4 as input u3 (64-bit value). (Binary data) and updates the content of the first register 4 to this calculated value (step S4). Subsequently, the first controller 12 activates the second function calculator 7 and The value v50 (64-bit binary data) of the second one-way function g, which receives the contents of the register 5 as the input, is calculated, and the contents of the second register 5 is updated to this calculated value (step S5). .

After that, the content of the memory I is incremented by 1 to 3 (step S6). In this way, the above process is repeated while the contents of the memory I are 3 to 52. Finally, when the process of step S1 is executed, the first secret data storage unit 8 stores the first secret data U1 to U52. Further, the second secret data storage unit 9 stores the second secret data V52 to V1. At this time, the content of the memory I is 53. As a result, step S1
Since the value of mi becomes -1 in the processing of, the processing is ended. At this time, the first secret data U1 to U52 are stored in the addresses 1 to 52 of the first secret data storage unit 8, respectively. In addition, addresses 1 to 5 of the second secret data storage unit 9
The second secret data V1 to V52 are stored in 2 respectively.

The storage state of the first secret data 8 at this stage is as shown in the data string (a) of FIG. The storage state of the second secret data storage unit 9 is as shown in the data string (b) of FIG. (2. Use of secret data) The first control unit 12 activates the first fusion function calculation unit 10, and an integer k of 1 or more and 52 or less,
For example, for k = 21, the first secret data U21 stored in the first secret data storage unit 8 and the second secret data V21 stored in the second secret data storage unit 9 are input. , The third secret data S by calculating the value of the fusion function h
21 = h (U21, V21) is generated (step S11).
The third secret data S21 is taken out of the secret data generation device 1 and used as an encryption key for encrypting the 21st record, for example. (3. Creation and Notification of Request Information) Now, when the operator of the secret data reproducing device 2 requests the secret data S14 to S26, the operator uses the secret data request information creating unit 15 to provide the secret data request information to that effect. Create (step S21). The secret data request information is notified by the head number 14 and the last number 26 of the requested secret data number. In addition, the second control unit 23 uses memories I and J (not shown).
The values of 14 and 26 are stored in.

Next, the secret data request information is sent to the secret data generating device 1 via the secret data request information transmitting means 13.
(Step S22), and then the secret data reading unit 11 temporarily stores the head request number 14 and the last request number 26 notified by the secret data request information transmitting means 13 (step S23).

Next, the secret data reading unit 11
Read the first secret data U14 from the area of the address 14 of the secret data storage unit 8 and read the second secret data V26 from the area of the address 26 of the second secret data storage unit 9 (step S24). The read secret data is sent to the secret data reproduction information transmission means 14. (4. Reproduction of first secret data) Secret data reproducing device 2
The second control unit 23 of the secret data reproduction information transmission means 1
14th first secret data U14 transmitted by No. 4
Is stored in the third register 16 and the integer 1 is set in the memory K (not shown) (step S31). Further, the contents of the first secret data reproduction value storage unit 20 are cleared to zero.

Next, the second control section 23 checks whether the content of m-ik is -2 (step S3).
2). In this case, the content is 37, so the second control unit 23 transfers the content of the third register 16 to the area of the first secret data reproduction value storage unit 20 at the address i + k-1 = 14 ( Step S33). This corresponds to the first secret data reproduction value U14.

Next, the second control section 23 activates the third function calculating section 18 to calculate the value of the first one-way function f which receives the contents of the third register 16 as an input. This is the value of u15 described above. Then, the contents of the third register 16 are updated to this calculated value (step S34).

Thereafter, the content of the memory K is incremented by 1 to 2 (step S35). In this way, the above process is repeated while the contents of the memory K are 2 to 39. Finally, when the process of step S32 is completed, the address 14 to the address 5 of the first secret data reproduction value storage unit 20
The first secret data reproduction values U14 to U52 are stored in 2 respectively. At this point, the content of the memory K is 40. As a result, in the process of step S32, mi
Since -k becomes -2, the processing ends.

The storage state of the first secret data reproduction value storage unit 20 at this stage is as shown in the data string (c) of FIG. (5. Reproduction of Second Secret Data) Secret Data Reproducing Device 2
The second control unit 23 of the secret data reproduction information transmission means 1
26th second secret data V26 transmitted by
Is stored in the fourth register 17, and the integer 1 is set in the memory K (not shown) (step S41). Further, the contents of the second secret data reproduction value storage unit 21 are cleared to zero.

Next, the second control section 23 checks whether the content of jk is -1 (step S42). In this case, the content is 25, so the second control unit 23 transfers the content of the fourth register 17 to the area of the second secret data reproduction value storage unit 21 at the address j−k + 1 = 26 ( Step S43). This corresponds to the second secret data reproduction value V26.

Next, the second control section 23 activates the fourth function calculating section 19 and calculates the value of the second one-way function g which receives the contents of the fourth register 17 as an input. This is the value of v51 described above. Then, the content of the fourth register 17 is updated to this calculated value (step S44).

After that, the content of the memory K is incremented by 1 to 2 (step S45). In this way, the above process is repeated while the contents of the memory K are 2 to 26. Finally, when the process of step S42 is completed, the addresses 1 to 26 of the second secret data reproduction value storage unit 21 are
The second secret data reproduction values V1 to V26 are stored in each. The contents of the memory K are 27 at this point. As a result, the content of jk becomes -1 in the process of step S42, and the process ends.

The storage state of the second secret data reproduction value storage unit 21 at this stage is as shown in the data string (d) of FIG. (6. Use of secret data reproduction value) The second control unit 23 activates the second fusion function calculation unit 22, and for the integer k of 14 or more and 26 or less, for example, k = 21, the first secret The first secret data reproduction value Uk stored in the data reproduction value storage unit 20 and the second secret data reproduction value Vk stored in the second secret data reproduction value storage unit 21 are input and merged. The value of the function h is calculated to generate the third secret data reproduction value Sk = h (Uk, Vk) (step S51).
This third secret data reproduction value is taken out of the secret data reproduction device 2 and used as a decryption key for decrypting the 21st record, for example.

As described above, in the present embodiment, the operator of the secret data reproducing device 2 operates the 13 consecutive secret data S14, S15, S16. ． When requesting S26, the secret data reproduction information notified from the secret data generating device 1 in response thereto is the 14th first secret data U14 and the 26th secret data.
Only the second secret data V26. The process (4) reproduces the first secret data U14 to U52, while the process (5) reproduces the second secret data data V1 to V26. Then, desired secret data having a number of 14 or more and 26 or less is obtained from the first and second secret data reproduction values having the same number. This significantly reduces the transfer data as compared with the case where all 13 pieces from the 14th secret data to the 26th secret data had to be delivered in the conventional example. This relative effect becomes more significant as the number of required secret data increases. That is, when the operator of the secret data reproducing device requests continuous secret data, the secret data reproducing information notified from the secret data creating device is one of the first secret data and the second secret data. There is only one, and desired secret data is calculated by a process using these secret data as initial values. This greatly reduces the transfer data as compared with the case where all the continuous secret data had to be delivered in the conventional example. This relative effect becomes more significant as the number of required secret data increases.

In the above embodiment, the secret data number k
When reproducing secret data in which is greater than or equal to i and less than or equal to j,
Regarding the first secret data, the secret data reproducing device 2
For the second secret data, the numbers were incremented by one from i to the maximum number, and the numbers of the second secret data were reduced from j by one to the minimum number. Even in this way, in order to obtain the third secret data Sk, Uk
And Vk are both required, so less than i or j +
You won't get third secret data with a number greater than 1, but
Alternatively, the secret data reproducing device 2 may be configured to reproduce the first secret data and the second secret data having numbers i to j.

In the above embodiment, when the number of the secret data generated by the secret data generating device 1 is 1 to m, it starts from an arbitrary number i of 1 or more and m or less and an arbitrary number of i or more and m or less. Although the case of reproducing the secret data ending with j has been described, the present invention is not limited to this, and particularly when i and j have specific values, a simpler configuration can be achieved. For example, when the maximum number to be reproduced is always equal to m, the second secret data generation process and the second secret data read process in the secret data generation device 1 and the second secret data in the secret data reproduction device 2 are performed. The process of designating the initial value of, the process of delivering, and the process of reproducing the second secret data are unnecessary, and the fusion function may be simply a function that outputs the first secret data (or its reproduced value). Also, if the lowest number to play is always equal to 1,
The first secret data generation process and the first secret data read process in the secret data generation device 1, the process of designating the initial value of the first secret data in the secret data reproduction device 2, the delivery process, and the first secret data The reproduction process of the secret data is unnecessary, and the fusion function may simply be a function for outputting the second secret data (or its reproduction value).

Further, in the above-described embodiment, the secret data series is made into two series of ascending order and descending order, and the third secret data is generated and used from them, but the invention is not limited to this.
The configuration may be such that only one series of secret data is used.

Further, in the above-mentioned embodiment, the secret data requested by the user is described as being continuous, but the invention is not limited to this, and it is possible to make a random request. You only need to have the first and last numbers.

[0063]

As is apparent from the above description, the present invention has an advantage that secret data can be delivered with a smaller amount of information than the required amount of information.

[Brief description of drawings]

FIG. 1 is a block diagram of a secret data delivery device according to an embodiment of the present invention.

FIG. 2A is a diagram showing a processing procedure for creating secret data in the embodiment, and FIG. 2B is a diagram showing a processing procedure for using secret data in the embodiment.

FIG. 3A is a diagram showing a processing procedure of creating and notifying request information in the embodiment, and FIG. 3B is a diagram showing a processing procedure of reproducing secret data in the embodiment. is there.

FIG. 4A is a diagram showing a processing procedure of reproducing secret data in the embodiment, and FIG. 4B is a diagram showing a processing procedure of using a secret data reproduction value in the embodiment. is there.

FIG. 5 is a diagram illustrating a storage state of secret data according to the embodiment.

FIG. 6 is a block diagram of a conventional secret data delivery device.

[Explanation of symbols]

 1, 40 Confidential Data Generation Device 2, 41 Confidential Data Reproduction Device 3, 42 Confidential Data Transmission Unit 11, 52 Confidential Data Reading Unit 15, 54 Confidential Data Request Information Creation Unit

Claims (2)

[Claims] 1. Uk + for an integer k of 1 or more and less than m using a one-way function f based on the head value U1 of the secret data.
Secret data generating means for sequentially obtaining 1 = f (Uk) to generate secret data Uk, and the i-th secret data Vi are transmitted in response to a request for the i-th and predetermined predetermined secret data. Based on the secret data transmission means and the secret data Vi, using the one-way function f, the i-th
A secret data delivery device comprising: secret data reproducing means for reproducing the predetermined secret data from the th secret data Vi. 2. A first secret data start value U1, a second secret data final value Vm, a first one-way function f, and a second one-way function g, wherein m is a positive integer. , Which has a fusion function h, sequentially obtains Uk + 1 = f (Uk) for an integer k of 1 or more and less than m to generate first secret data Uk, and Vm- for an integer k of 1 or more and less than m. k = g (Vm-k + 1) is sequentially obtained to generate the second secret data Vm-k, and an integer k of 1 or more and m or less
With respect to Sk = h (Uk, Vk), the secret data generating means for generating the third secret data, and the i-th, j-th, and predetermined i-th to j-th Secret data transmitting means for transmitting the i-th first secret data Vi and the j-th second secret data Vj in response to the third secret data request, the first one-way function f, and the first one-way function f. 2 has a one-way function g and the fusion function h, and Ui + k = f (Ui + k-1) from the transmitted i-th first secret data Ui for an integer k of 1 or more. ) Sequentially,
The first secret data subsequent to the th secret data is reproduced, and Vj-k = g (Vj-k + 1) is sequentially obtained from the transmitted j-th second secret data Vj for an integer k of 1 or more. To recover the second secret data before the j-th, and an integer k between i and j
And a secret data reproducing means for reproducing the third secret data by Sk = h (Uk, Vk).