WO1999045674A1

WO1999045674A1 - Automatic encoding/decoding system

Info

Publication number: WO1999045674A1
Application number: PCT/JP1998/000883
Authority: WO
Inventors: Hiroshi Nozawa; Harumi Takebayashi
Original assignee: Tact Service Co., Ltd.; Chaotic Toys Factory Ltd.; Jujo Electronics Corporation; Moct Ltd.
Priority date: 1998-03-04
Filing date: 1998-03-04
Publication date: 1999-09-10
Also published as: CN1291391A

Abstract

An automatic encoding/decoding system with which useless arithmetic processings can be eliminated from an arbitrary position and efficient decoding can be performed. When plain text data are encoded, pseudorandom numbers which are used for encoding the next plain text data are generated by a first pseudorandom number generating means in accordance with encoded data encoded immediately before. The next plain text data are encoded into coded data by an encoding means by using the pseudorandom numbers. When coded data are decoded, pseudorandom numbers for decoding are generated by a second pseudorandom number generating means in accordance with the first coded data of continuous coded data, and the next coded data of the continuous code data are decoded into plain text data by a decoding means by using the pseudorandom numbers generated by the second pseudorandom number generating means. Thus, useless arithmetic processings can be eliminated from an arbitrary position and efficient decoding can be performed.

Description

Specification

Automatic encryption and decryption system

(Technical field)

The present invention relates to an automatic encryption / decryption system for protecting data.

(Background technology)

Hitherto, as a method of encrypting and protecting data, a method of replacing information data with a certain rule, and a method of adding random data and hiding the data have been proposed. In the former case, it is difficult to start decryption from an arbitrary place or time because a combination of multiple data is used in both the encryption and decryption processes.

In the latter case, it is necessary to generate the same random data in both the encryption and decryption processes. Therefore, even if it is desired to decrypt only the last data, it is necessary to generate random data sequentially from the beginning. Needed. This was extremely inefficient when dealing with large amounts of data, for example image data. In addition, it was necessary to share the so-called initial values and seeds in both the encryption and decryption processes. When performing encrypted communication, these values had to be transmitted, which was inconvenient and dangerous.

(Disclosure of the Invention)

The present invention has been made in view of the above-mentioned current situation of encryption and decryption, and has as its object to realize an automatic decryption that can efficiently perform decryption from an arbitrary position while eliminating useless operations. An object of the present invention is to provide an encryption / decryption system.

For this purpose, the present inventors have conducted intensive research and have succeeded in using the immediately preceding encrypted data as an initial value to generate a pseudo-random number in order, as an initial value. Found that only one pseudo-random number was needed, and completed a cryptosystem that could be decrypted at any time. In addition, after further intensive research, they have introduced a differential structure into a functional system, and have completed an industrially extremely effective cryptosystem that functions without sharing the initial values.

In order to achieve the above object, a first embodiment of the present invention provides an automatic encryption / decryption system that encrypts plaintext data using pseudo-random numbers and decrypts the encrypted data into plaintext data. In the decryption system, A first pseudo-random number generating means for generating a pseudo-random number to be used for encrypting the next plain data based on the immediately-encrypted data already encrypted when encrypting a plurality of plain text data;

Encryption means for encrypting the next plaintext data into encrypted data using the pseudorandom number generated by the first pseudorandom number generation means;

A second pseudo-random number generating means for generating a pseudo-random number at the time of decryption based on the first encrypted data of the continuous encrypted data when decrypting the plurality of encrypted data;

Decryption means for decrypting the next successive cipher data into plaintext data using the pseudorandom number generated by the second pseudorandom number generation means;

It is characterized by an automatic encryption and decryption system having

Similarly, in order to achieve the above-mentioned object, the second embodiment of the present invention provides a method in which 0 <xc (t) +1 is an internal retained value of the cipher at the discrete time t, and 0.5-yc (t) <0. 5 is the sum of inputs to the chaotic cipher at discrete time t, 0 <zc (t) <1 is the output of the chaotic cipher at discrete time t, and 0 <s (t) <1 is the input at discrete time t. 0 <α <1 is the attenuation constant of the internal holding value X c (t), 0 <3 <0.5 is the gain constant from the sum yc (t) of inputs to the output zc (t), 0 <7 <0.5 as a threshold for the internal holding value xc (t), and 0 <e <1 as a coupling constant that determines the intensity of chaotic modulation.

X c (t + 1) = (1-ε) {α χ c (t) + (1-a) z c (t)} + ε s (t)

z c (t) = f {y c (t)} = 0-y c (t) <

z c (t) = f {y c (t)} = 0.5 (y c (t) / β + 1)

'—— β≤ c (t) ≤ β z c (t)-f {y c (t)} = 1 -y c (t)> β

y c (t) = r ~ x c (t)

Encryption means for encrypting the plaintext data into encrypted data based on

0 <d (t) <1 is the internal held value of the chaotic decoder at discrete time t, 1 0.5 <yd (t) <0.5 is the sum of inputs to the chaotic decoder at discrete time t, 0 Let <zd (t) <1 be the output of the chaotic decoder at discrete time t, and 0 * s (t) * 1 be the decoded signal at discrete time t.

X d (t + 1) = (1-ε) {α χ d (t) + (1-α) ζ d (t)} zd (t) = f {yd (t)} = 0 -yd (t ) <-β

d (t) = f {y d (t)}. 5 (y d (t) / β + 1)

'—— β≤γ ά (t) ≤ β z d (t) = f {y d (t)} = l… d (t)> β

y d (t) = r-c (t)

氺 s (t) = [xc (t + 1)-xd (t + 1)-(1 ε) a {xc (t)-xd (t)}] κ _ε

Decryption means for decrypting the encrypted data based on

An automatic encryption / decryption system having the following features.

(Brief description of drawings)

FIG. 1 is a block diagram showing the configuration of an embodiment of the encryption system according to the present invention.

FIG. 2 is a block diagram showing a configuration of an embodiment of the decoding system according to the present invention.

FIG. 3 is an explanatory diagram of the encryption processing according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram of the decoding process according to the embodiment of the present invention.

FIG. 5 is an explanatory diagram of application of the embodiment of the present invention to a personal computer.

(Best mode for carrying out the invention)

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. In the drawings, 1, 16, and 20 are subtractors, 2, 6, 15, 17, 17, 22, 24, and 2 7 is a multiplier, 3, 18, 25, 26 is an adder, 5, 23 is a function operator, 7, 8a, 8b, 10, 0, 1, 1 and 2 are registers, 1, 3, Reference numerals 14 and 28 denote delay circuits, and reference numerals 29, 30, 30, 31, 32 and 33 denote registers.

In the encryption system according to the embodiment of the present invention, as shown in FIG. 1, the output terminal of the multiplier 27 connected to the input terminal of the system is connected to one input terminal of the adder 26, The output terminal of the adder 26 is connected to the output terminal of the system and the input terminal of the delay circuit 28, and the output terminal of the delay circuit 28 is connected to the inverting input terminal of the subtractor 21 and one input of the multiplier 24. The output terminal of the multiplier 24 is connected to one input terminal of the adder 25.

The output terminal of the subtracter 21 is connected to one input terminal of the multiplier 22, and the output terminal of the multiplier 22 is connected to one input terminal of the function operator 23. The output terminal of the adder 25 is connected to the other input terminal of the adder 25, and the output terminal of the adder 25 is connected to the other input terminal of the adder 26.

Register 31 is connected to the non-inverting input terminal of subtracter 21, register 32 is connected to the other input terminal of multiplier 22, and register 33 is connected to the other input terminal of function calculator 23. Register 30 is connected to the other input terminal of 24, and register 29 is connected to the other input terminal of multiplier 27, respectively.

In the encryption means according to the present invention, 0 <xc (t) <1 is set to an internally held value at discrete time t, and 0.5 <yc (t) to 0.5 is set to a chaotic cipher at discrete time t. 0, zc (t) x 1 is the output of the chaotic cipher at discrete time t, 0 x s (: t) x 1 is the input signal at discrete time t, and 0 <«<1 is the internal The damping constant of the holding value c (t), 0 x / 3 x 0.5 is the gain constant from the input sum yc (t) to the output zc (t), 0 < ₇ x 0.5 is the internal holding value xc ( t), where 0 <£ <1 is a coupling constant that determines the intensity of chaotic modulation.

c (t + 1) = (1-ε) {χ c (t) + (1-) z c (t)} + ε s

(t) (1) z c (t)

zc (t) zc (t)

(2) encrypts the plaintext data into encrypted data based on yc (t) == r-xc (t) (3), Equations (1) and (2) are rewritten into the following equations (8) and (9) for convenience of encryption in the encryption system of FIG.

X c (t + 1) = z e (t) + (1 ε) a x c (t) + ε s (t)-(8) z e (t) = 0: y c (t) k;

= (1 ~ ε) (1 ~ a) / 2 β-y c (i) +

(1-ε) (1-a) / 2: I yc (t) \ ≤ β-(9) = (1-ε) (1-a): yc (t)> β 'One embodiment of the present invention The encryption in the example will be described with reference to FIG.

In this embodiment, the expression (3) is executed by the subtractor 21, the expression (9) is executed by the multiplier 22 and the function calculator 23, and the expression (8) is executed by the multiplier 24.27. , Performed by adders 25, 26.

In this case, starting from the initial value c 0, the internal value is sequentially updated by the above equations (3) and (9). The current internal value is subtracted from the value of the register 31 by the subtracter 21, multiplied by the value of the register 32 by the multiplier 22, and sent to the function calculator 23. The output of the function operation unit 23 is sent to an adder 25, which is added to the current internal value multiplied by the value of the register 30 by a multiplier 24 and sent to an adder 26. This signal is the signal that disturbs the original signal and encrypts it.

This signal is added by the adder 26 to the original signal multiplied by the value of the register 29 by the multiplier 27. In this way, the encryption is obtained. This is also the new internal value. Here, if the value of the register 29, that is, l / ε is set to a power of 2, the multiplier 27 can be completed by a shift operation unit, and needless to say, it can be configured at high speed and at low cost. .

As shown in FIG. 2, in the decoding system according to the embodiment of the present invention, the input terminals of the system are connected to one input terminal of the subtractor 1, the input terminal of the delay circuit 13 and the non-inverting human terminal of the subtractor 20. The output terminal of the subtractor 20 is connected to one input terminal of the multiplier 15, and the output terminal of the multiplier 5 is connected to the output terminal of the system. The output terminal is connected to one input terminal of the multiplier 6, and The output terminal 6 is connected to one input terminal of the function calculator 5, and the output terminal of the function calculator 5 is connected to one input terminal of the adder 3. The output terminal of the adder 3 is connected to the input terminal of the delay circuit 13, the output terminal of the delay circuit 13 is connected to one input terminal of the multiplier 2, and the output terminal of the multiplier 2 Is connected to the other input terminal of the adder 3.

The output terminal of the delay circuit 13 is also connected to the non-inverting input terminal of the subtractor 16, and the output terminal of the subtracter 16 is connected to one input terminal of the multiplier 17. The output terminal of the multiplier 17 is connected to one input terminal of the adder 18, and the other input terminal of the adder 18 is connected to the output terminal of the adder 3.

Further, the output terminal of the adder 18 is connected to the inverting input terminal of the subtractor 20, and the output terminal of the adder 20 is connected to one input terminal of the adder 15 as described above.

Register 10 is connected to the inverting input terminal of subtracter 1, register 11 is connected to the other input terminal of multiplier 6, register 12 is connected to the other input terminal of function calculator 5, and the other input terminal of multiplier 2 is connected. The register 8b is connected to the terminal, the register 8a is connected to the other input terminal of the multiplier 17, and the register 7 is connected to the other input terminal of the multiplier 1.5. In the decoding means according to the embodiment of the present invention, 0 × xd (t) × 1 is the internal holding value of the power decoder at the discrete time t, and 0.5 <yd (t) × 0.5 is the discrete time. The sum of the inputs to the chaotic decoder at t, 0 x zd (t) <1 as the output of the chaotic decoder at discrete time t, and 0 <* s (t) x 1 as the decoded signal at discrete time t. ,

X d (t-ten) = (1--ε) {α χ d (t) + (1-a) z d (t)}

… (1 0) z d (t) = f {y d (t)} = 0 d (t)

z d (t) = f {y d (t)} = 0 5 (y d (t) / yS + 1)

… One y d (t) ≤ β z d (t) = f {y d (t)} = 1 ••• y d (t)> β

(1 1) yd (t) = 7— xc (t) (1 2) * s (t) = (xc (t + 1)-d (t. + 1) one (1 ε) a (xc (t)

-x d (t)}] κ £-decrypts encrypted data based on (1 3),

Equations (10), (11), and (13) are converted to the following equations (14) to (16) for convenience in decoding by the decoding system in FIG. rewrite.

X d (t + 1) = z f (t) + (l-£) x d (t)-(1 4) z f (t) = 0: y d (t) <-β

= (1— ε) (1-a) / 2 β · γ d (t) + (1−ε)

(1-a) / 2: I y d (t) \ ≤ β-(1 5)

= (1-ε) (l ~ a): y d (t)> ^ '

* s (t) = [xc (t + l)-d (t-1)-(1-ε) a {xc (t)-xd (t)}] / ε-(16) The decoding according to the embodiment will be described with reference to FIG.

In the embodiment of the present invention, the subtractor 1 executes the equation (1 2), and the arithmetic unit 2 and the adder

3 executes the above equation (14), and the function calculator 5 and the multiplier 6 execute the above equation (15).

In these operations, the constants of the respective expressions are given in registers 7 to 12. It is used to use the data before the delay circuits 13 and 14. In these operations, the initial values d 0 and c 0 are used for the first decoding process, respectively. Needless to say, c 0 is the first data of the ciphertext. The multiplier 15 can execute the shift operation if ε is set to a power of two, and it goes without saying that the processing time can be reduced.

Some of the encryption circuits and the decryption circuits shown in FIGS. 1 and 2 can be used in common. When a device having both functions is to be manufactured, the cost can be reduced by using them in common. In the case of a single function, an ASIC with both functions can be used. In the above-described embodiment of the present invention, a case where a chaotic dynamic system including independent initial conditions is incorporated in the encryption process and the decryption process has been described. It is basically shown in Fig. 3 and Fig. 4. Figure 3 shows the process of encrypting three pieces of data. Pseudorandom numbers are added by the process (b) using the first data of the data sequence (a) to be encrypted and an optional initial value (c). The first encrypted data is obtained. For the second encrypted data, the process (b) works using the second data of the data sequence (a) and the first encrypted data given instead of the initial value, and the second encrypted data is obtained. .

Figure 4 shows how the encrypted data sequence (d) can be decrypted to obtain a decrypted data sequence (f) by the process (e) of removing pseudorandom numbers. Next, this process is formulated using an equation. Assuming that the data sequence to be encrypted is s, the random data used for encryption 1 is ε, the parameter indicating the degree of encryption is ε, and the encrypted data sequence is X, the encryption process is as follows: Can be indicated by

x c (t + 1) = (l-ε) r (t) + εs (t)-(17)

R (t) = g (x c (t))-(18) where g denotes the process of generating pseudorandom numbers, and can use congruential methods or chaotic dynamical systems. Next, the decoding process will be described using S 'as a decoded signal. S ′ (t) − {xc (t + 1) − (l−ε) R (t)} / ε− (19) As described above, according to this method, according to the above equation (18), As shown in Eq. (19), X (t + 1) and X (t) can be used to obtain S '(t) .Therefore, for any t, there is no extra calculation, Decryption is possible. Also, there is no need to explicitly send initial values. However, the first data cannot be decrypted without the initial value used to encrypt the first data. Here it goes without saying that S 'matches s.

Then, as already explained in one embodiment of the present invention, the initial value is also used for decryption by incorporating a chaotic dynamical system consisting of independent initial conditions in the encryption process and the decryption process. Not automatic encryption · Decryption system is obtained.

When the embodiment of the present invention is applied to a personal computer, data to be encrypted is transmitted from the personal computer 34 to the encrypting device 35 using the USB, which is a general-purpose I / 0 port, as shown in FIG. The encryption device 35 encrypts the data by a built-in electronic circuit, and sends the obtained encryption back to the personal computer using USB. At this time, put together The plaintext may be sent to the user, and the ciphertext may be sent back as a whole, or may be sent and received for each data. If an initial value is needed for the first decryption, the data should be prepended to the ciphertext. The reason is that the value is used for decoding the first data. With this configuration, it is not necessary to specially treat the decoding process of the first decoding in the decoding algorithm. In other words, decrypting the subsequent data can be obtained by processing the data that connects the first data of two consecutive data as the initial value as encryption.

(Industrial applicability)

As described above, according to the present invention, data at an arbitrary position in a data string can be instantaneously decoded using two pieces of data without using unnecessary operations, and particularly, large capacity. It has a great effect on data, for example, image data. Also, according to the present invention, when a chaotic dynamical system is used, a dynamical system consisting of independent initial conditions is used for encryption and decryption, so that there is no need to know any initial values. Is obtained. Furthermore, by properly specifying ε, an image in which the original image has been disturbed can be obtained by arbitrarily controlling the degree of “disturbance”. This is particularly effective in cases where the service is provided with a different password.

Claims

The scope of the claims

1. In an automatic encryption / decryption system that encrypts plaintext data into encrypted data using pseudo-random numbers and decrypts the encrypted data into plaintext data,

A first pseudo-random number generating means for generating a pseudo-random number used for encrypting the next plain data based on the immediately-encrypted data which has already been encrypted when encrypting a plurality of plain text data;

An automatic encryption / decryption system comprising:

2. 0 <c (t) <1 is the internal value of the cipher at discrete time t, 0.5 <yc (t) <0.5 is the sum of inputs to the chaotic cipher at discrete time t, Let 0 <zc (t) <1 be the output of the chaotic cipher at discrete time t, 0 x s (t) x 1 be the input signal at discrete time t, and 0 <α <1 the internal hold value X c (t) 0 <) 3 <0.5 is the gain constant from input sum yc (t) to output zc (t), 0 <r <0.5 is the threshold for the internal holding value xc (t), 0 <to <1 is the coupling constant that determines the intensity of chaotic modulation.

X c (t + 1) = (1-e) {a c (t) + (1-) z c (t)} + ε s (t)

z c (t) = f {y c (t)} = 0 to y c (t) k — z c (t) = f {y c (t)} = 0.5 (y c (t) / β + 1)

'—— β≤ γ c (t) ≤ β z c (t) = f {y c (t)} = 1-y c (t)> β

y c (t) = 7-x c (t)

Encryption means for encrypting the plaintext data into encrypted data based on 0 <xd (t) <1 is the internal holding value of the chaotic decoder at discrete time t, and 0.5 <yd (t) <0.5 is the sum of inputs to the chaotic decoder at discrete time t, 0 < zd (t): I is the output of the chaotic decoder at discrete time t, and 0 * s (t) <1 is the decoded signal at discrete time t.

X d (t + 1) = (1-e) {axd (t) + (1-α) ζ d (t)} zd (t) = f {yd (t)} = 0-yd (t) < -β

z d (t)-f {y d (t)} = 0.5 (y d (t) / β + I)

… One; S≤ y d (t) β z d (t) = f {y d (t)} = 1… y d (t)> β

y d (t) = 7-x c (t)

* s (t) = [x c (t + 1)-x d (t + 1) one (1-) a X c (t) x d (t)}] / ε

Decryption means for decrypting the encrypted data based on

An automatic encryption / decryption system comprising: