JPH11327436A - Ciphering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the safeness of a ciphering device for ciphering a normal sentence by inhibiting the correspondence of a normal sentence to a ciphered sentence at the rate of one to one. SOLUTION: An inputted normal sentence is corrected and encoded by a correcting/encoding means 1. A data operation means 2 changes the encoded data string within a range of the number of bits allowed to be corrected at their errors. Thereby the normal sentence corresponds to a ciphered sentence to be transmitted at the rate of one to N. When the transmitted data string is directly decoded by a decoding means 4, the original normal sentence can be generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for encrypting communication data used for digital communication.

[0002]

2. Description of the Related Art Conventionally, in data communication, various encryption devices have been used to prevent transmitted data from being known to a third party. As one of the conventional encryption techniques, encryption by DES and encryption by RSA are known. As shown in FIG. 5A, DES encryption converts data to be transmitted (hereinafter, referred to as plaintext) into a ciphertext by using a private key. The decryption is performed using the public key. Also RS
In the encryption by A, as shown in FIG. 5B, the plaintext is encrypted using a public key, the ciphertext is transmitted, and at the time of decryption, the plaintext is converted into a plaintext using a private key.

[0003]

However, according to such a conventional encryption method, the text to be transmitted, that is, the plain text and the corresponding encrypted text correspond to each other as shown in FIG. doing. That is, if the key, the plaintext, and the encryption method are the same, the same encrypted text will be generated. Therefore, there is a problem that if a large number of pairs of plaintext and ciphertext are obtained, a key may be found from the relationship between them.

The present invention has been made in view of such a conventional problem, and it is possible to generate a large number of ciphertexts from one plaintext instead of having a one-to-one correspondence between plaintexts and ciphertexts. And to improve the security of the encryption.

[0005]

According to a first aspect of the present invention, there is provided a correction coding unit for correcting and coding input data by a block code, and a range of the number of bits that can be corrected by the correction coding unit. Within, data operation means for encrypting by randomly changing the correction-encoded data, and decoding means for performing error correction processing and decoding the data operated by the data operation means, It is characterized by having.

According to a second aspect of the present invention, there is provided a correction coding means for correcting and coding input data by using a convolutional code, and a correction coding means for correcting the input data within a range of the number of error-correctable bits by the correction coding means. Data operating means for encrypting the data operated by the data operating means by randomly changing the data, and decoding means for performing error correction processing on the data operated by the data operating means and decoding the data. Is what you do.

The invention of claim 3 of the present application is directed to claim 1 or 2
In the above-mentioned encryption apparatus, the data operation means operates using a pseudo-random data sequence.

According to a fourth aspect of the present invention, in the encryption apparatus according to any one of the first to third aspects, the encryption unit encrypts input data and outputs the encrypted data to the correction encoding unit, Encryption decryption means for decrypting the encrypted data decrypted by the decryption means.

According to a fifth aspect of the present invention, a first correction encoding means for correcting and encoding input data;
A first data operation means for encrypting the error-encoded data by randomly changing the error-encoded data within a range of the number of bits which can be corrected by the error correction encoding means; and an input from the first data operation means. N-th (n ≧ 2) correction coding means for correcting and coding the selected data;
An n-th data operation means for encrypting the error-encoded data by randomly changing the error-encoded data within a range of the number of error-correctable bits by the one error-encoding means; An n-th to a first decoding means for performing error correction and decoding each of the data strings operated by the operation means.

[0010] The invention according to claim 6 of the present application is the encryption device according to any one of claims 1 to 5, characterized in that it has a wired transmission path for transmitting the output of the data operation means. .

According to a seventh aspect of the present invention, in the encryption apparatus according to any one of the first to fifth aspects, a wireless transmission path for transmitting an output of the data operation means is provided. .

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a first embodiment of the present invention will be described with reference to FIG. In this embodiment, first, the input plaintext is encoded by the correction encoding unit 1. The correction encoding unit 1 may be one that encodes with a block code using a generation formula, for example, or may be one that uses a convolutional code. Examples of block coding include random error correction codes such as Hamming codes, BCH codes, and Reed-Solomon codes, and burst error correction codes such as fire codes and shortened cyclic codes. Examples of the convolutional code include a random error correction code such as a self-orthogonal code, a Viterbi decoding code, and a sequential decoding code, and a burst error correction code such as a Hager-Berker code, Iwanade-Massie code, and Berlecamp-Massie code. Here, it is assumed that correction coding is performed using an error correction code using a generation formula. Then, the encoded sentence is provided to the data operation means 2. The data operation means 2 converts the data string within the range that can be corrected when the correction coding means 1 performs the correction coding. That is, if it is possible to correct even if there is an error in the number of bits, which is the encoding by the correction encoding means 1, the number of bits less than that is randomly converted and encrypted. This data string operation can be performed using, for example, a pseudo-random code. For example, assuming that the data sequence by the error correction code is 100 bits and the number of correctable bits is 10 bits, uniform random numbers from 1 to 100 are generated by, for example, an M-sequence pseudo-random code, and the generated pseudo-random code is used. Reverse the determined bit. Number of times less than the number of bits that can correct this process (n times)
Performs data string operations by repeating within. In this way, the input plain text and the cipher text output from the data manipulation means have a one-to-N (= ₁₀₀ C _n ) correspondence.

[0013] Such a cipher text is transmitted via the transmission path 3 and is decrypted by the decrypting means 4 on the receiving side. The decoding unit 4 performs decoding corresponding to the encoding of the data encoding unit 1. When the above-described generation formula is used, decoding is performed using the same generation formula. In this way, if there is no data error between the data operation means 2 and the decoding means 4, or if there is an error, the number of bits converted by the data operation means 1 + the number of error bits generated in the transmission process If the sum is within an error-correctable range, the data can be converted into the original data (plaintext) by decoding by the decoding means 4.

FIG. 2 is a diagram showing an example of this conversion. For example, it is assumed that the plaintext is "01234" and "0123426261" is generated by the processing of the correction encoding means 1, for example. The data operation means 2 randomly converts the three digits into another numerical value. For example, as shown in the figure, “0913452661”, “512392261”
Is converted as follows. These ciphertexts are transmitted via the transmission path 3 and if there is no error in the transmission path, the original plaintext "01" is encoded by the decoding means 4 as it is.
234 "can be generated. In this case, the original plaintext and the ciphertext to be transmitted face one-to-N, and do not correspond one-to-one. Therefore, different ciphertexts are transmitted for each use even for the same plaintext. Even if a large number of pairs of plaintexts and ciphertexts are obtained, the relationship between the data is low. Is difficult to recognize, and security during transmission can be improved.

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, a plaintext is encrypted in advance, and correction encoding and data manipulation are performed on the plaintext in the same manner as in the first embodiment. That is, the input plaintext is once subjected to encryption processing by the encryption means 11. The encryption means 11 uses the above-described conventional encryption processing, for example, encryption processing such as DES or RSA. In this case, encryption processing is performed using a public key or a private key. Then, the encrypted cipher text is subjected to the correction encoding process by the correction encoding unit 1 in the same manner as in the first embodiment.
Then, data operation is performed by the data operation means 2 to randomly convert the ciphertext. Then, decoding processing is performed by the decoding means 4 via the transmission path 3. The ciphertext encoded in this way is restored by the encryption restoring means 12. In this case, restoration processing by DES or RSA is performed corresponding to the encryption unit 11. That way, in addition to the traditional encryption process,
By performing the correction coding and the data string operation by the correction coding means, the relationship between the plaintext to be transmitted and the ciphertext to be transmitted becomes more complicated. Decoding is extremely difficult.

Next, a third embodiment of the present invention will be described. In this embodiment, the same first correction encoding means 1 and first data string operating means 2 as those in the first embodiment are used.
And correction coding. In this embodiment, as shown in FIG. 4, a sentence subjected to a data string operation by the first data operation means 2 is further converted into a second
The correction coding means 21 performs correction coding. Then, the generated correction code is subjected to the same data string operation by the second data operation means 22 and transmitted through the transmission path 3. Then, a second decoding process corresponding to the correction coding of the second correction coding unit 21 is performed by the decoding unit 23 on the transmitted signal. Further, first correction encoding means 1
Are decoded by the decoding means 4 in the same manner as in the first embodiment. In this way, the original plaintext can be decrypted.

Although the correction encoding process and the data string operation are repeated twice here, the same process may be repeated a number of times, and the decoding process may be performed the number of times. Further, the processing of the plurality of correction coding means may be not limited to the same correction coding but may be performed by combining different correction coding processings among the various correction codings described above. In this case, the correspondence between the original plaintext and the transmitted ciphertext is further complicated, and the security of the transmitted text can be improved.

Although the data transmission path is not explicitly described in the present embodiment, it goes without saying that data may be transmitted by wire or wirelessly. The present invention can also be applied to a case where data is simply stored in a large-capacity memory or the like. Needless to say, such a data transmission method can be applied to data transmission in a contactless identification system.

[0019]

As described above in detail, according to the present invention, the plaintext to be transmitted and the ciphertext to be transmitted do not correspond one-to-one, but correspond to one-to-N. It is extremely difficult to find an encryption algorithm even if a pair of a password and a ciphertext is obtained, and the effect that data security can be improved can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a schematic diagram showing an example of plaintext and ciphertext of the encryption device according to the embodiment.

FIG. 3 is a block diagram showing a configuration of an encryption device according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of an encryption device according to a third embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a conventional encryption device.

[Explanation of symbols]

 1, 21 Correction encoding means 2 Data operation means 3 Transmission path 4, 22 Decoding means 11 Encryption means 12 Encryption recovery means

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04L 9/30 H04L 9/00 663Z

Claims (7)

[Claims] 1. A correction coding means for correcting and coding input data by a block code, and changing the correction-coded data at random within a range of the number of error-correctable bits by the correction coding means. An encryption device comprising: a data operation unit that performs encryption by causing the data operation unit to perform encryption; and a decryption unit that performs error correction processing on data operated by the data operation unit and decrypts the data. 2. A correction coding means for correcting and coding input data by a convolutional code, and changing the correction-coded data at random within a range of the number of error-correctable bits by said correction coding means. An encryption device comprising: a data operation unit that performs encryption by causing the data operation unit to perform encryption; and a decryption unit that performs error correction processing on data operated by the data operation unit and decrypts the data. 3. The encryption apparatus according to claim 1, wherein said data operation means operates using a pseudo-random data sequence. 4. An encryption unit for encrypting input data and outputting the encrypted data to the correction encoding unit, and a decryption unit for decrypting the encrypted data decrypted by the decryption unit. The encryption device according to claim 1, wherein: 5. A first method for correcting and coding input data.
Correction encoding means, and first data manipulation means for encrypting by randomly changing the correction-encoded data within a range of the number of error-correctable bits by the first correction encoding means. An n-th (n ≧ 2) correction coding unit for correcting and coding data input from the first data operation unit; and a number of error-correctable bits by the (n−1) -th correction coding unit. An n-th data operation means for encrypting the random number of the correction-encoded data by randomly changing the data within the range; and error correction for the data string operated by the n-th to first data operation means, respectively. To perform decoding
And a first decryption means. 6. The encryption apparatus according to claim 1, further comprising a wired transmission path for transmitting an output of said data operation means. 7. The encryption device according to claim 1, further comprising a wireless transmission path for transmitting an output of said data operation means.