JP5431191B2 - Authenticated stream cipher encryption apparatus, authenticated stream cipher decryption apparatus, encryption method, decryption method, and program - Google Patents

Description

  The present invention relates to an encrypted stream cipher encryption apparatus, an authenticated stream cipher decryption apparatus, an encryption method, a decryption method, and a program that can be expanded to an authenticated stream cipher without changing the stream cipher algorithm main body. About.

  In recent years, various services using computers have been provided. In many services, encryption is used to conceal communication. The most common encryption method is a common key encryption method that performs encryption / decryption with a single key, but the common key encryption method is roughly divided into a block encryption method and a stream encryption method.

  The former is the method that is most commonly used, but the latter has been attracting attention in recent years because it is superior in processing speed. On the other hand, there is a method called authenticated encryption. This is an algorithm for simultaneously realizing message authentication and encryption with one algorithm. There are two types of encryption with authentication: Authenticate-then-Encrypt (authenticator is generated from plaintext) and Encrypt-then-Authentate (Et-A, authenticator is generated from ciphertext). (For example, refer nonpatent literature 1.).

Philip Hawkes, Cameron McDonald, Michael Paddon, Gregory G. Rose and Mirag Wiggers de Vries, “Specification for NLSv2,” New Stream Cipher Designs, LNCS, Vol. 4986, 2008.

  However, conventionally, in order to change the stream cipher to an authenticated cipher, it has been necessary to redesign the algorithm, or to consider incorporating an authentication function from the design stage. Furthermore, there is also the fact that almost all authenticated stream ciphers have been broken by attacks, and there are almost no secure stream ciphers with authentication. At present, no Et-A type scheme has been proposed.

  Therefore, the present invention has been made in view of the above-described problem, and an encrypted stream cipher encryption apparatus and an authenticated stream cipher that can be expanded to an authenticated stream cipher without changing the stream cipher algorithm main body. An object of the present invention is to provide a decryption device, an encryption method, a decryption method, and a program.

  The present invention proposes the following matters in order to solve the above problems. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected and demonstrated, it is not limited to this.

  (1) The present invention is an encryption apparatus for stream cipher with authentication, comprising a key sequence generation means (for example, equivalent to the key sequence generation unit 20 of FIG. 1) for generating a key sequence, and the generated key sequence Dividing means for dividing into two (for example, corresponding to the key sequence dividing unit 30 in FIG. 1), and a first ciphertext generated by performing an exclusive OR operation on one of the divided key sequences and the plaintext An XOR operator (for example, equivalent to the first XOR operator 40 in FIG. 1), a feedback shift register (for example, equivalent to the feedback shift register 50 in FIG. 1), which is a memory for creating a message authenticator, A second XOR operator (for example, equivalent to the second XOR operator 60 in FIG. 1) that performs an exclusive OR operation on any two of the feedback shift registers, and the second XOR operation Output A third XOR operator that performs an exclusive OR operation on the data, the generated ciphertext, and the other key sequence and outputs output data to the feedback shift register (for example, the third XOR in FIG. 1). A computing unit 70), a coupling means for coupling the message authenticator output from the feedback shift register and the generated ciphertext (for example, the coupling unit 80 in FIG. 1), and the coupled authentication An encryption apparatus for stream cipher with authentication, characterized by comprising a transmission means for transmitting a stream cipher (for example, corresponding to the transmission section 90 in FIG. 1) is proposed.

  According to this invention, the key sequence generation means generates a key sequence. The dividing means divides the generated key sequence into two. The first XOR operator performs an exclusive OR operation on one of the divided key sequences and the plaintext to generate a ciphertext. The feedback shift register is a memory for creating a message authenticator. The second XOR operator performs an exclusive OR operation on any two of the feedback shift registers. The third XOR operator performs an exclusive OR operation on the output data of the second XOR operator, the ciphertext, and the other key sequence, and outputs the output data to the feedback shift register. The combining means combines the message authenticator output from the feedback shift register and the generated ciphertext. The transmitting means transmits the combined stream cipher with authentication. Therefore, an authenticated stream cipher can be generated without changing the stream cipher algorithm main body. In addition, since the stream cipher algorithm to be used is not changed at all, if the stream cipher is secure, a secure stream cipher with authentication can be configured. Furthermore, since the operation to be added is small and fast, a high-speed stream cipher with authentication can be realized.

  (2) In the encryption apparatus for stream cipher with authentication of (1), the present invention is characterized in that after the input of the ciphertext is completed, a fixed bit string is input and the feedback shift register is idled. An encryption apparatus for an authenticated stream cipher is proposed.

  According to the present invention, after the ciphertext input is completed, a fixed bit string is input, and the feedback shift register is idled. Thereby, safety can be improved.

  (3) The present invention proposes an encrypted stream cipher encrypting apparatus according to (1), wherein the feedback shift register is a linear feedback shift register. .

  According to the present invention, the feedback shift register is a linear feedback shift register. Therefore, the message authenticator can be generated with a simple configuration and calculation.

  (4) The encrypted stream cipher encrypting apparatus according to (1), wherein the encrypted stream cipher encrypting apparatus includes a non-linear function, and the feedback shift register is a non-linear feedback shift register. Has proposed.

  According to the present invention, a nonlinear function is provided, and the feedback shift register is a nonlinear feedback shift register. That is, the configuration is more complicated than in the case of the linear feedback shift register, but the message authenticator can be generated even if the nonlinear feedback shift register is used.

  (5) The present invention relates to the encrypted stream cipher encrypting apparatus according to (1), wherein when the feedback shift register is in units of words, the output data is multiplied by a coefficient. A device is proposed.

  According to the present invention, when the feedback shift register is in units of words, the output data is multiplied by the coefficient. As a result, processing in bit units can be performed.

  (6) The present invention is an authentication stream cipher decryption device for decrypting an authenticated stream cipher, and a receiving means for receiving the authenticated stream cipher (for example, corresponding to the receiving unit 110 in FIG. 3); Separation means for separating the ciphertext from the received stream cipher with authentication (for example, equivalent to the separation unit 120 in FIG. 3) and key sequence generation means for generating a key sequence (for example, the key sequence generation unit 20 in FIG. 3) 3), a dividing means for dividing the generated key sequence into two (for example, equivalent to the key sequence dividing unit 30 in FIG. 3), and the exclusive OR of the one of the divided key sequences and the ciphertext A first XOR operator (for example, equivalent to the first XOR operator 40 in FIG. 3) that performs an operation to generate plaintext, and a feedback shift register (for example, FIG. 3) that is a memory for creating a message authenticator Three Feedback shift register 50) and a second XOR operator (for example, the second XOR operator 60 in FIG. 3) that performs an exclusive OR operation on any two of the feedback shift registers. ), And a third XOR operator (for example, FIG. 5) that performs an exclusive OR operation between the output data of the second XOR operator, the ciphertext, and the other key sequence and outputs the output data to the feedback shift register. 3 is equivalent to the third XOR operator 100), and a decryption apparatus for an authenticated stream cipher is provided.

  According to this invention, the receiving means receives the stream cipher with authentication. The separating means separates the ciphertext from the received authenticated stream cipher. The key sequence generation unit generates a key sequence. The dividing means divides the generated key sequence into two. The first XOR operator performs an exclusive OR operation on one of the divided key sequences and the ciphertext to generate plaintext. The feedback shift register is a memory for creating a message authenticator. The second XOR operator performs an exclusive OR operation on any two of the feedback shift registers. The third XOR operator performs an exclusive OR operation on the output data of the second XOR operator, the ciphertext, and the other key sequence, and outputs the output data to the feedback shift register. Therefore, the authenticated stream cipher can be decrypted without changing the stream cipher algorithm main body.

  (7) In the decryption apparatus for authenticated stream cipher according to (6), the present invention is characterized in that after the ciphertext has been input, a fixed bit string is input and the feedback shift register is idled. And a decryption apparatus for an authenticated stream cipher.

  According to the present invention, after the ciphertext input is completed, a fixed bit string is input, and the feedback shift register is idled. Thereby, safety can be improved.

  (8) The present invention proposes a decryption apparatus for authenticated stream ciphers, wherein the feedback shift register is a linear feedback shift register for the decryption apparatus for authenticated stream ciphers of (6). .

  According to the present invention, the feedback shift register is a linear feedback shift register. Therefore, the message authenticator can be generated with a simple configuration and calculation.

  (9) The present invention relates to the apparatus for decrypting authenticated stream ciphers of (6), comprising a nonlinear function, wherein the feedback shift register is a nonlinear feedback shift register. Has proposed.

  According to the present invention, a nonlinear function is provided, and the feedback shift register is a nonlinear feedback shift register. That is, the configuration is more complicated than in the case of the linear feedback shift register, but the message authenticator can be generated even if the nonlinear feedback shift register is used.

  (10) The present invention relates to the decryption apparatus for authenticated stream cipher according to (6), wherein when the feedback shift register is in units of words, the output data is multiplied by a coefficient. A device is proposed.

  According to the present invention, when the feedback shift register is in units of words, the output data is multiplied by the coefficient. As a result, processing in bit units can be performed.

  (11) The present invention is an encryption method in an encryption apparatus for an authenticated stream cipher, and includes a first step (for example, corresponding to step S101 in FIG. 2) for reading an initial key and an initial vector, and an initialization process A second step (for example, corresponding to step S102 in FIG. 2), a third step for executing key sequence generation processing and generating a key sequence (for example, corresponding to step S103 in FIG. 2), A fourth step (for example, corresponding to step S104 in FIG. 2) for dividing the generated key sequence into two, an exclusive OR operation between the one key sequence and the plaintext, and outputting a ciphertext Exclusive of any two of the fifth step (for example, equivalent to step S105 in FIG. 2) and the feedback shift register that is a memory for creating the message authenticator A sixth step (for example, in step S106 in FIG. 2) is performed by performing an exclusive OR operation on the data that has undergone the OR operation, the other divided key sequence, and the ciphertext, and sequentially inputting them to the feedback shift register. And a seventh step (for example, corresponding to step S107 in FIG. 2) of inputting a fixed bit string and performing idle rotation of the feedback shift register to output a message authenticator after the ciphertext input is completed. An eighth step of combining the message authenticator and the generated ciphertext (for example, corresponding to step S108 in FIG. 2), and a step of transmitting the combined message authenticator and the generated ciphertext. 9 has been proposed (for example, corresponding to step S109 in FIG. 2).

  According to the present invention, the initial key and the initial vector are read and the initialization process is performed. Next, a key sequence generation process is executed to generate a key sequence. The generated key sequence is divided into two, an exclusive OR operation is performed on one of the divided key sequences and the plaintext, and a ciphertext is output. Of the feedback shift register, which is a memory for creating a message authenticator, the exclusive OR operation of the data obtained by performing the exclusive OR operation of any two registers and the other divided key sequence and the ciphertext is performed. And sequentially input to the feedback shift register. After the ciphertext is input, a fixed bit string is input, the feedback shift register is rotated, and a message authenticator is output. Then, the message authenticator and the generated ciphertext are combined, and the combined message authenticator and the generated ciphertext are transmitted. Therefore, an authenticated stream cipher can be generated without changing the stream cipher algorithm main body. In addition, since the stream cipher algorithm to be used is not changed at all, if the stream cipher is secure, a secure stream cipher with authentication can be configured. Furthermore, since the operation to be added is small and fast, a high-speed stream cipher with authentication can be realized.

  (12) The present invention is a decryption method in a decryption apparatus for an authenticated stream cipher, and includes a first step (for example, corresponding to step S201 in FIG. 4) for receiving the authentic stream cipher and the reception The second step of separating the ciphertext from the authenticated stream cipher (for example, equivalent to step S202 of FIG. 4) and the third step of reading the initial key and initial vector (for example, equivalent to step S203 of FIG. 4) ), A fourth step (for example, corresponding to step S204 in FIG. 4) for performing the initialization process, and a fifth step (for example, step in FIG. 4) for executing the key series generation process and generating the key series 6) (corresponding to step S206 in FIG. 4), one of the divided key sequences and the encryption Among the seventh step (for example, corresponding to step S207 in FIG. 4) and a feedback shift register that is a memory for creating a message authenticator. Eighth step (for example, for performing exclusive OR operation of data obtained by performing exclusive OR operation of two registers and the other divided key sequence and ciphertext, and sequentially inputting to the feedback shift register And the ninth step (for example, FIG. 4), after inputting the ciphertext, inputting a fixed bit string, emptying the feedback shift register, and outputting a message authenticator. Corresponding to step S209) and the first message verifying whether or not the output message authenticator matches the separated message authenticator Step (e.g., corresponding to step S210 in FIG. 4) proposes a decoding method characterized by comprising a, a.

  According to the present invention, the authenticated stream cipher is received, and the ciphertext is separated from the received authenticated stream cipher. Next, an initial key and an initial vector are read and an initialization process is performed. Furthermore, a key sequence generation process is executed to generate a key sequence. The generated key sequence is divided into two, an exclusive OR operation is performed on one of the divided key sequences and the ciphertext, and a plaintext is output. Of the feedback shift register, which is a memory for creating a message authenticator, the exclusive OR operation of the data obtained by performing the exclusive OR operation of any two registers and the other divided key sequence and the ciphertext is performed. And sequentially input to the feedback shift register. After the ciphertext is input, a fixed bit string is input, the feedback shift register is rotated, and a message authenticator is output. Then, it is verified whether or not the output message authenticator matches the separated message authenticator. Therefore, the stream cipher with authentication can be decrypted without changing the stream cipher algorithm main body, and authentication can be performed by checking the message authenticator.

  (13) The present invention is a program for executing an encryption method in an encrypted stream cipher encryption apparatus, and is a first step for reading an initial key and an initial vector (for example, corresponding to step S101 in FIG. 2) ), A second step (for example, corresponding to step S102 of FIG. 2) for executing the initialization process, and a third step (for example, step of FIG. 2) for executing the key series generation process and generating the key series S103), a fourth step (for example, equivalent to step S104 in FIG. 2) for dividing the generated key sequence into two, and an exclusive OR operation between the one key sequence and the plaintext. Among the fifth step (for example, corresponding to step S105 in FIG. 2) for outputting the ciphertext and the feedback shift register that is a memory for creating the message authenticator, A sixth step of performing an exclusive OR operation of the data obtained by performing the exclusive OR operation of the two registers, the other divided key sequence, and the ciphertext, and sequentially inputting them to the feedback shift register ( For example, the seventh step (e.g., corresponding to step S106 in FIG. 2) and after inputting ciphertext is completed, a fixed bit string is input, the feedback shift register is idled, and a message authenticator is output (for example, FIG. 2), the eighth step of combining the message authenticator and the generated ciphertext (for example, corresponding to step S108 of FIG. 2), the combined message authenticator and the generation Has proposed a program for executing the ninth step (for example, corresponding to step S109 in FIG. 2) for transmitting the encrypted ciphertext.

  According to the present invention, the initial key and the initial vector are read and the initialization process is performed. Next, a key sequence generation process is executed to generate a key sequence. The generated key sequence is divided into two, an exclusive OR operation is performed on one of the divided key sequences and the plaintext, and a ciphertext is output. Of the feedback shift register, which is a memory for creating a message authenticator, the exclusive OR operation of the data obtained by performing the exclusive OR operation of any two registers and the other divided key sequence and the ciphertext is performed. And sequentially input to the feedback shift register. After the ciphertext is input, a fixed bit string is input, the feedback shift register is rotated, and a message authenticator is output. Then, the message authenticator and the generated ciphertext are combined, and the combined message authenticator and the generated ciphertext are transmitted. Therefore, an authenticated stream cipher can be generated without changing the stream cipher algorithm main body. In addition, since the stream cipher algorithm to be used is not changed at all, if the stream cipher is secure, a secure stream cipher with authentication can be configured. Furthermore, since the operation to be added is small and fast, a high-speed stream cipher with authentication can be realized.

  (14) The present invention is a program for executing a decryption method in a decryption apparatus for an authenticated stream cipher, and includes a first step (for example, in step S201 in FIG. Equivalent), a second step of separating the ciphertext from the received stream cipher with authentication (eg, equivalent to step S202 of FIG. 4), and a third step of reading the initial key and initial vector (eg, FIG. 4) (corresponding to step S203 of FIG. 4), a fourth step of executing initialization processing (for example, corresponding to step S204 of FIG. 4), and a fifth step of executing key sequence generation processing to generate a key sequence ( For example, corresponding to step S205 in FIG. 4), a sixth step (for example, corresponding to step S206 in FIG. 4) for dividing the generated key sequence into two, A seventh step (for example, equivalent to step S207 in FIG. 4) that performs an exclusive OR operation on one of the divided key sequences and the ciphertext and outputs a plaintext, and a memory for creating a message authenticator Among the certain feedback shift registers, the exclusive OR operation of the data obtained by performing the exclusive OR operation of any two registers, the other divided key sequence, and the ciphertext is performed, and sequentially in the feedback shift register. After the eighth step (for example, corresponding to step S208 in FIG. 4) and ciphertext input, a fixed bit string is input, the feedback shift register is rotated, and a message authenticator is output. 9 (for example, corresponding to step S209 in FIG. 4), the output message authenticator and the separated message authenticator are combined. Tenth step of verifying whether (e.g., corresponding to step S210 in FIG. 4) proposes a program for executing a, a.

  According to the present invention, the authenticated stream cipher is received, and the ciphertext is separated from the received authenticated stream cipher. Next, an initial key and an initial vector are read and an initialization process is performed. Furthermore, a key sequence generation process is executed to generate a key sequence. The generated key sequence is divided into two, an exclusive OR operation is performed on one of the divided key sequences and the ciphertext, and a plaintext is output. Of the feedback shift register, which is a memory for creating a message authenticator, the exclusive OR operation of the data obtained by performing the exclusive OR operation of any two registers and the other divided key sequence and the ciphertext is performed. And sequentially input to the feedback shift register. After the ciphertext is input, a fixed bit string is input, the feedback shift register is rotated, and a message authenticator is output. Then, it is verified whether or not the output message authenticator matches the separated message authenticator. Therefore, the stream cipher with authentication can be decrypted without changing the stream cipher algorithm main body, and authentication can be performed by checking the message authenticator.

  According to the present invention, it is possible to generate an authenticated stream cipher without changing the stream cipher algorithm main body. Further, there is an effect that the stream cipher with authentication can be decrypted without changing the stream cipher algorithm main body, and authentication can be performed by checking the message authenticator. In addition, since the stream cipher algorithm to be used is not changed at all, if the stream cipher is secure, a secure stream cipher with authentication can be configured. Furthermore, since the operation to be added is small and fast, a high-speed stream cipher with authentication can be realized. In addition, since tampering can be checked without decryption, the amount of calculation can be reduced when only tampering checking is desired.

It is a figure which shows the structure of the encryption apparatus of the stream cipher with authentication which concerns on this embodiment. It is a figure which shows the process of the encryption apparatus of the stream cipher with authentication which concerns on this embodiment. It is a figure which shows the structure of the decoding apparatus of the stream cipher with authentication which concerns on this embodiment. It is a figure which shows the process of the decoding apparatus of the stream cipher with authentication which concerns on this embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Note that the constituent elements in the present embodiment can be appropriately replaced with existing constituent elements and the like, and various variations including combinations with other existing constituent elements are possible. Therefore, the description of the present embodiment does not limit the contents of the invention described in the claims.

<Configuration of encryption device for stream cipher with authentication>
As shown in FIG. 1, the encryption apparatus for stream cipher with authentication according to the present embodiment includes an initialization processing unit 10, a key sequence generation unit 20, a key sequence division unit 30, and a first XOR operator 40. And a feedback shift register 50, a second XOR operator 60, a third XOR operator 70, a combiner 80, and a transmitter 90.

  The initialization processing unit 10 reads an initial key and an initial vector and performs initialization processing. The key sequence generation unit 20 executes a key sequence generation process to generate a key sequence. The key sequence dividing unit 30 divides the generated key sequence into two. Here, one is used for encryption and the other is used for creating a message authenticator.

  The first XOR operator 40 performs an exclusive OR operation on one of the divided key sequences and the plaintext to generate a ciphertext. The feedback shift register 50 is a memory for creating a message authenticator, and may be a linear feedback shift register or a non-linear feedback shift register. In addition, the feedback shift register 50 has the same length as the message authenticator, and when the feedback shift register 50 is in word units, a feedback shift register in bit units can be configured by multiplying by the coefficient α.

  The second XOR operator 60 performs an exclusive OR operation on any two of the feedback shift registers 50. The third XOR operator 70 performs an exclusive OR operation between the output data of the second XOR operator 60, the ciphertext, and the other key sequence, and outputs the output data to the feedback shift register 50.

  The combining unit 80 combines the message authenticator output from the feedback shift register 50 and the generated ciphertext. The transmitting unit 90 transmits the combined authenticated stream cipher to the decryption device.

<Processing of encryption device for authenticated stream cipher>
With reference to FIG. 2, processing of the encryption apparatus for the stream cipher with authentication according to the present embodiment will be described.

  First, the initialization processing unit 10 reads an initial key and an initial vector (step S101), and performs an initialization process (step S102). The key sequence generation unit 20 executes key sequence generation processing and generates a key sequence (step S103). Then, the key sequence dividing unit 30 divides the generated key sequence into two (step S104).

  The first XOR operator 40 performs an exclusive OR operation on one of the divided key sequences and the plaintext, and outputs a ciphertext (step S105). Further, the third XOR operator 70 is the other key divided from the data obtained by performing the exclusive OR operation of any two registers in the feedback shift register 50 that is a memory for creating the message authenticator. An exclusive OR operation between the sequence and the ciphertext is performed and sequentially input to the feedback shift register 50 (step S106).

  After the ciphertext input is completed, a fixed bit string is input, the feedback shift register 50 is rotated, and a message authenticator is output (step S107). The combining unit 80 combines the message authenticator and the generated ciphertext (step S108), and the transmitting unit 90 transmits the combined message authenticator and the generated ciphertext (step S109).

  Therefore, the stream cipher with authentication can be generated without changing the stream cipher algorithm main body. In addition, since the stream cipher algorithm to be used is not changed at all, if the stream cipher is secure, a secure stream cipher with authentication can be configured. Furthermore, since the operation to be added is small and fast, a high-speed stream cipher with authentication can be realized. In addition, since tampering can be checked without decryption, the amount of calculation can be reduced when only tampering checking is desired.

<Configuration of Decryption Apparatus for Stream Cipher with Authentication>
As shown in FIG. 3, the decryption apparatus for authenticated stream cipher according to the present embodiment includes an initialization processing unit 10, a key sequence generation unit 20, a key sequence division unit 30, and a first XOR operator 40. And a feedback shift register 50, a second XOR operator 60, a third XOR operator 100, a receiver 110, a separator 120, and a verifier 130. In addition, since it has the same function about the component which attaches | subjects the code | symbol same as said encryption apparatus of stream encryption with authentication, the detailed description is abbreviate | omitted.

  The third XOR operator 100 performs an exclusive OR operation between the output data of the second XOR operator 60, the ciphertext, and the other key sequence, and outputs the output data to the feedback shift register 50. The receiving unit 110 receives the authenticated stream cipher from the authenticated stream cipher encryption apparatus.

  The separation unit 120 separates the received authenticated stream cipher into a ciphertext and a message authenticator. The verification unit 130 compares the message authenticator output from the feedback shift register 50 with the message authenticator obtained by separation and verifies whether or not they match.

<Processing of Decryption Device for Stream Cipher with Authentication>
With reference to FIG. 4, the processing of the decryption apparatus for the stream cipher with authentication according to the present embodiment will be described.

  First, the receiving unit 110 receives the authenticated stream cipher (step S201), and separates the ciphertext from the authenticated stream cipher received by the separating unit 120 (step S202). Next, the initialization processing unit 10 reads an initial key and an initial vector (step S203), and performs an initialization process (step S204). The key sequence generation unit 20 executes key sequence generation processing to generate a key sequence (step S205). Then, the key sequence dividing unit 30 divides the generated key sequence into two (step S206).

  The first XOR operator 40 performs an exclusive OR operation on one of the divided key sequences and the ciphertext, and outputs a plaintext (step S207). Further, the third XOR operator 100 is the other key divided from the data obtained by performing the exclusive OR operation of any two registers in the feedback shift register 50 which is a memory for creating the message authenticator. An exclusive OR operation between the sequence and the ciphertext is performed and sequentially input to the feedback shift register 50 (step S208).

  After the ciphertext input is completed, a fixed bit string is input, the feedback shift register 50 is rotated, and a message authenticator is output (step S209). Then, the verification unit 130 verifies whether or not the output message authenticator matches the separated message authenticator (step S210).

  Accordingly, the stream cipher with authentication can be decrypted without changing the stream cipher algorithm main body, and authentication can be performed by checking the message authenticator.

  Note that the processing of the authentication stream cipher encryption apparatus and the authentication stream cipher decryption apparatus is recorded on a computer-readable recording medium, and the program recorded on the recording medium is stored in the authentication stream cipher encryption apparatus and The authentication stream cipher encryption apparatus and the authentication stream cipher decryption apparatus according to the present invention can be realized by causing the authentication stream cipher decryption apparatus to read and execute the authentication. The computer system here includes an OS and hardware such as peripheral devices.

  Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW (World Wide Web) system is used. The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line.

  The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

  The embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to the embodiments, and includes designs and the like that do not depart from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10; Initialization process part 20; Key sequence production | generation part 30; Key sequence division | segmentation part 40; 1st XOR operator 50; Feedback shift register 60; 2nd XOR operator 70; 3rd XOR operator 80; Unit 90; transmission unit 100; third XOR operator 110; reception unit 120; separation unit 130; verification unit

Claims (14)

An encryption device for an authenticated stream cipher,
Key sequence generation means for generating a key sequence;
Dividing means for dividing the generated key sequence into two;
A first XOR operator that performs an exclusive OR operation between the one of the divided key sequences and the plaintext to generate a ciphertext;
A feedback shift register which is a memory for creating a message authenticator;
A second XOR operator that performs an exclusive OR operation on any two of the feedback shift registers;
A third XOR operator that performs an exclusive OR operation between the output data of the second XOR operator, the generated ciphertext, and the other key sequence, and outputs the output data to the feedback shift register;
Combining means for combining the message authenticator output from the feedback shift register and the generated ciphertext;
Transmitting means for transmitting the combined stream cipher with authentication;
An apparatus for encrypting stream cipher with authentication, comprising:   2. The apparatus for encrypting stream cipher with authentication according to claim 1, wherein after the input of the ciphertext is completed, a fixed bit string is input to rotate the feedback shift register.   2. The encrypted stream cipher encryption apparatus according to claim 1, wherein the feedback shift register is a linear feedback shift register.   The apparatus for encrypting stream cipher with authentication according to claim 1, further comprising a non-linear function, wherein the feedback shift register is a non-linear feedback shift register.   2. The encrypted stream cipher encryption apparatus according to claim 1, wherein when the feedback shift register is in units of words, the output data is multiplied by a coefficient. An apparatus for decrypting an authenticated stream cipher that decrypts an authenticated stream cipher,
Receiving means for receiving the authenticated stream cipher,
Separating means for separating the ciphertext from the received stream cipher with authentication;
Key sequence generation means for generating a key sequence;
Dividing means for dividing the generated key sequence into two;
A first XOR operator that performs an exclusive OR operation between the divided one key sequence and ciphertext to generate plaintext;
A feedback shift register which is a memory for creating a message authenticator;
A second XOR operator that performs an exclusive OR operation on any two of the feedback shift registers;
A third XOR operator that performs an exclusive OR operation between the output data of the second XOR operator, the ciphertext, and the other key sequence, and outputs the output data to the feedback shift register;
An apparatus for decrypting authenticated stream ciphers, comprising:   7. The apparatus for decrypting authenticated stream cipher according to claim 6, wherein after the input of the ciphertext is completed, a fixed bit string is input to rotate the feedback shift register.   The apparatus for decrypting authenticated stream cipher according to claim 6, wherein the feedback shift register is a linear feedback shift register.   7. The apparatus for decrypting authenticated stream cipher according to claim 6, further comprising a nonlinear function, wherein the feedback shift register is a nonlinear feedback shift register.   7. The apparatus for decrypting authenticated stream cipher according to claim 6, wherein when the feedback shift register is in units of words, the output data is multiplied by a coefficient. An encryption method in an encrypted stream cipher encryption device,
A first step of reading an initial key and an initial vector;
A second step of performing an initialization process;
Executing a key sequence generation process to generate a key sequence;
A fourth step of dividing the generated key sequence into two parts;
A fifth step of performing an exclusive OR operation of the one divided key sequence and the plaintext, and outputting a ciphertext;
An exclusive OR operation of data obtained by performing an exclusive OR operation on any two of the feedback shift registers, which are memories for creating a message authenticator, and the other divided key sequence and ciphertext And sequentially inputting the feedback shift register to the feedback shift register,
A seventh step of inputting a fixed bit string after the end of ciphertext input, performing idle rotation of the feedback shift register, and outputting a message authenticator;
An eighth step of combining the message authenticator and the generated ciphertext;
A ninth step of transmitting the combined message authenticator and the generated ciphertext;
An encryption method comprising: A decryption method in a decryption device for an authenticated stream cipher,
A first step of receiving the authenticated stream cipher;
A second step of separating ciphertext from the received authenticated stream cipher;
A third step of reading an initial key and an initial vector;
A fourth step of performing initialization processing;
A fifth step of executing a key sequence generation process to generate a key sequence;
A sixth step of dividing the generated key sequence into two parts;
A seventh step of performing an exclusive OR operation between the one divided key sequence and the ciphertext, and outputting a plaintext;
An exclusive OR operation of data obtained by performing an exclusive OR operation on any two of the feedback shift registers, which are memories for creating a message authenticator, and the other divided key sequence and ciphertext And an eighth step of sequentially inputting to the feedback shift register,
A ninth step of inputting a fixed bit string after the ciphertext input is completed, performing idle rotation of the feedback shift register, and outputting a message authenticator;
A tenth step of verifying whether the output message authenticator matches the separated message authenticator;
A decoding method characterized by comprising: A program for executing an encryption method in an encrypted stream cipher encryption device,
A first step of reading an initial key and an initial vector;
A second step of performing an initialization process;
Executing a key sequence generation process to generate a key sequence;
A fourth step of dividing the generated key sequence into two parts;
A fifth step of performing an exclusive OR operation of the one divided key sequence and the plaintext, and outputting a ciphertext;
An exclusive OR operation of data obtained by performing an exclusive OR operation on any two of the feedback shift registers, which are memories for creating a message authenticator, and the other divided key sequence and ciphertext And sequentially inputting the feedback shift register to the feedback shift register,
A seventh step of inputting a fixed bit string after the end of ciphertext input, performing idle rotation of the feedback shift register, and outputting a message authenticator;
An eighth step of combining the message authenticator and the generated ciphertext;
A ninth step of transmitting the combined message authenticator and the generated ciphertext;
A program for running. A program for executing a decryption method in a decryption device for an authenticated stream cipher,
A first step of receiving the authenticated stream cipher;
A second step of separating ciphertext from the received authenticated stream cipher;
A third step of reading an initial key and an initial vector;
A fourth step of performing initialization processing;
A fifth step of executing a key sequence generation process to generate a key sequence;
A sixth step of dividing the generated key sequence into two parts;
A seventh step of performing an exclusive OR operation between the one divided key sequence and the ciphertext, and outputting a plaintext;
An exclusive OR operation of data obtained by performing an exclusive OR operation on any two of the feedback shift registers, which are memories for creating a message authenticator, and the other divided key sequence and ciphertext And an eighth step of sequentially inputting to the feedback shift register,
A ninth step of inputting a fixed bit string after the ciphertext input is completed, performing idle rotation of the feedback shift register, and outputting a message authenticator;
A tenth step of verifying whether the output message authenticator matches the separated message authenticator;
A program for running.

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