Stream-cipher encrypting device, stream-cipher decrypting device, stream-cipher encrypting method, stream-cipher decrypting method, and program

Abstract

A stream-cipher encrypting method includes first step of expanding an initial key in advance to generate an expanded key by a key expanding unit, a second step of inputting the generated expanded key and an initial value in the initialization processing by an initialization processing unit to carry out the initialization processing, a third step by a key-sequence generating unit of inputting a feedback value from a non-linear unit after the initialization processing is finished, parallelly processing non-linear processing, and maintaining and processing rearranging processing and a multiplication result, which is for obtaining the feedback value, as a data table to generate a key sequence by a non-linear function, and a fourth step of carrying out an exclusive-OR operation of the generated key sequence and a plaintext to generate an encrypted text by an encrypted-text generating unit.

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         9 . A stream-cipher encrypting device comprising:
 a key-sequence generating unit that receives input of an expanded key obtained by expanding an initial key and an initial value in initialization processing, receives input of a feedback value from a non-linear unit after the initialization processing is finished, and generates a key sequence;   an input switching unit that inputs the expanded key obtained by expanding the initial key and the initial value to the key-sequence generating unit in the initialization processing and, after the initialization processing is finished, inputs the feedback value from the non-linear unit to the key-sequence generating unit;   an encrypted-text generating unit that   parallelly processes non-linear processing executed by the key-sequence generating,   causes a non-linear function provided in the key-sequence generating unit to maintain rearranging processing and a multiplication result, which is for obtaining the feedback value, as a data table, and   carries out an exclusive-OR operation of the generated key sequence and a plaintext to generate an encrypted text.   
     
     
         10 . A stream-cipher encrypting device comprising:
 an initial-key expanding unit that expands an initial key;   a key-sequence generating unit that receives input of the expanded initial key and an initial value in initial processing, receives input of a feedback value from a non-linear unit after the initialization processing is finished, and generates a key sequence;   an input switching unit that inputs an expanded key obtained by expanding the initial key and the initial value to the key-sequence generating unit in the initialization processing and, after the initialization processing is finished, inputs the feedback value from the non-linear unit to the key-sequence generating unit; and   an encrypted-text generating unit that   parallelly processes non-linear processing executed by the key-sequence generating unit,   causes a non-linear function provided in the key-sequence generating unit to maintain rearranging processing and a multiplication result, which is for obtaining the feedback value, as a data table, and   carries out an exclusive-OR operation of the generated key sequence and a plaintext to generate an encrypted text.   
     
     
         11 . The stream-cipher encrypting device according to  claim 1 , wherein
 the input switching unit is a flip-flop.   
     
     
         12 . A stream-cipher decrypting device comprising:
 a key-sequence generating unit that receives input of an expanded key obtained by expanding an initial key and an initial value in initialization processing, receives input of a feedback value from a non-linear unit after the initialization processing is finished, and generates a key sequence;   an input switching unit that inputs the expanded key obtained by expanding the initial key and the initial value to the key-sequence generating unit in the initialization processing and, after the initialization processing is finished, inputs the feedback value from the non-linear unit to the key-sequence generating unit;   a plaintext generating unit that   parallelly processes non-linear processing executed by the key-sequence generating,   causes a non-linear function provided in the key-sequence generating unit to maintain rearranging processing and a multiplication result, which is for obtaining the feedback value, as a data table, and   carries out an exclusive-OR operation of the generated key sequence and an encrypted text to generate a plaintext.   
     
     
         13 . A stream-cipher encrypting device comprising:
 an initial-key expanding unit that expands an initial key;   a key-sequence generating unit that receives input of the expanded initial key and an initial value in initial processing, receives input of a feedback value from a non-linear unit after the initialization processing is finished, and generates a key sequence;   an input switching unit that inputs an expanded key obtained by expanding the initial key and the initial value to the key-sequence generating unit in the initialization processing and, after the initialization processing is finished, inputs the feedback value from the non-linear unit to the key-sequence generating unit; and   a plaintext generating unit that   parallelly processes non-linear processing executed by the key-sequence generating unit,   causes a non-linear function provided in the key-sequence generating unit to maintain rearranging processing and a multiplication result, which is for obtaining the feedback value, as a data table, and   carries out an exclusive-OR operation of the generated key sequence and an encrypted text to generate a plaintext.   
     
     
         14 . The stream-cipher decrypting device according to  claim 4 , wherein
 the input switching unit is a flip-flop.   
     
     
         15 . A stream-cipher encrypting method comprising:
 a first step of expanding an initial key in advance to generate an expanded key by a key expanding unit;   a second step of inputting the generated expanded key and an initial value in the initialization processing by an initialization processing unit to carry out the initialization processing;   a third step by a key-sequence generating unit of inputting a feedback value from a non-linear unit after the initialization processing is finished, parallelly processing non-linear processing, and maintaining and processing rearranging processing and a multiplication result, which is for obtaining the feedback value, as a data table to generate a key sequence by a non-linear function; and   a fourth step of carrying out an exclusive-OR operation of the generated key sequence and a plaintext to generate an encrypted text by an encrypted-text generating unit.   
     
     
         16 . A stream-cipher encrypting method comprising:
 a first step of expanding an initial key to generate an expanded key by a key expanding unit;   a second step of inputting the generated expanded key and an initial value in the initialization processing by an initialization processing unit to carry out the initialization processing;   a third step by a key-sequence generating unit of inputting a feedback value from a non-linear unit after the initialization processing is finished, parallelly processing non-linear processing, and maintaining and processing rearranging processing and a multiplication result, which is for obtaining the feedback value, as a data table to generate a key sequence by a non-linear function; and   a fourth step of carrying out an exclusive-OR operation of the generated key sequence and a plaintext to generate an encrypted text by an encrypted-text generating unit.   
     
     
         17 . A stream-cipher decrypting method comprising:
 a first step of expanding an initial key in advance to generate an expanded key by a key expanding unit;   a second step of inputting the generated expanded key and an initial value in the initialization processing by an initialization processing unit to carry out the initialization processing;   a third step by a key-sequence generating unit of inputting a feedback value from a non-linear unit after the initialization processing is finished, parallelly processing non-linear processing, and maintaining and processing rearranging processing and a multiplication result, which is for obtaining the feedback value, as a data table to generate a key sequence by a non-linear function; and   a fourth step of carrying out an exclusive-OR operation of the generated key sequence and an encrypted text to generate a plaintext by a plaintext generating unit.   
     
     
         18 . A stream-cipher encrypting method comprising:
 a first step of expanding an initial key in advance to generate an expanded key by a key expanding unit;   a second step of inputting the generated expanded key and an initial value in the initialization processing by an initialization processing unit to carry out the initialization processing;   a third step by a key-sequence generating unit of inputting a feedback value from a non-linear unit after the initialization processing is finished, parallelly processing non-linear processing, and maintaining and processing rearranging processing and a multiplication result, which is for obtaining the feedback value, as a data table to generate a key sequence by a non-linear function; and   a fourth step of carrying out an exclusive-OR operation of the generated key sequence and an encrypted text to generate a plaintext by a plaintext generating unit.   
     
     
         19 . Apparatus comprising a non-transitory computer readable storage medium having a computer program encoded thereon and stored in a computer readable format, the computer program being executable by a computer to cause the computer to execute a stream-cipher encrypting method comprising:
 a first step of expanding an initial key in advance to generate an expanded key by a key expanding unit;   a second step of inputting the generated expanded key and an initial value in the initialization processing by an initialization processing unit to carry out the initialization processing;   a third step by a key-sequence generating unit of inputting a feedback value from a non-linear unit after the initialization processing is finished, parallelly processing non-linear processing, and maintaining and processing rearranging processing and a multiplication result, which is for obtaining the feedback value, as a data table to generate a key sequence by a non-linear function; and   a fourth step of carrying out an exclusive-OR operation of the generated key sequence and a plaintext to generate an encrypted text by an encrypted-text generating unit.   
     
     
         20 . Apparatus comprising a non-transitory computer readable storage medium having a computer program encoded thereon and stored in a computer readable format, the computer program being executable by a computer to cause the computer to execute a stream-cipher encrypting method comprising:
 a first step of expanding an initial key to generate an expanded key by a key expanding unit;   a second step of inputting the generated expanded key and an initial value in the initialization processing by an initialization processing unit to carry out the initialization processing;   a third step by a key-sequence generating unit of inputting a feedback value from a non-linear unit after the initialization processing is finished, parallelly processing non-linear processing, and maintaining and processing rearranging processing and a multiplication result, which is for obtaining the feedback value, as a data table to generate a key sequence by a non-linear function; and   a fourth step of carrying out an exclusive-OR operation of the generated key sequence and a plaintext to generate an encrypted text by an encrypted-text generating unit.   
     
     
         21 . Apparatus comprising a non-transitory computer readable storage medium having a computer program encoded thereon and stored in a computer readable format, the computer program being executable by a computer to cause the computer to execute a stream-cipher decrypting method comprising:
 a first step of expanding an initial key in advance to generate an expanded key by a key expanding unit;   a second step of inputting the generated expanded key and an initial value in the initialization processing by an initialization processing unit to carry out the initialization processing;   a third step by a key-sequence generating unit of inputting a feedback value from a non-linear unit after the initialization processing is finished, parallelly processing non-linear processing, and maintaining and processing rearranging processing and a multiplication result, which is for obtaining the feedback value, as a data table to generate a key sequence by a non-linear function; and   a fourth step of carrying out an exclusive-OR operation of the generated key sequence and an encrypted text to generate a plaintext by a plaintext generating unit.   
     
     
         22 . Apparatus comprising a non-transitory computer readable storage medium having a computer program encoded thereon and stored in a computer readable format, the computer program being executable by a computer to cause the computer to execute a stream-cipher decrypting method comprising:
 a first step of expanding an initial key to generate an expanded key by a key expanding unit;   a second step of inputting the generated expanded key and an initial value in the initialization processing by an initialization processing unit to carry out the initialization processing;   a third step by a key-sequence generating unit of inputting a feedback value from a non-linear unit after the initialization processing is finished, parallelly processing non-linear processing, and maintaining and processing rearranging processing and a multiplication result, which is for obtaining the feedback value, as a data table to generate a key sequence by a non-linear function; and   a fourth step of carrying out an exclusive-OR operation of the generated key sequence and an encrypted text to generate a plaintext by a plaintext generating unit.