Program conversion device and program execution device

A system comprising a program conversion device for generating, from one original program, one distribution program that is executable on a plurality of program execution devices having different security levels, and a program execution device that operates in accordance with the distribution program, wherein

• the program conversion device comprises:
• a storage unit for storing an original program composed of a plurality of computer instructions;
• an obfuscation unit for obfuscating the original program to generate an obfuscated program;
• a generating unit for generating conversion information that indicates conversion to be applied to the obfuscated program so as to alter an obfuscation level correspondingly to one of the security levels;
• and
• an output unit for outputting a distribution program that is composed of the obfuscated program and the conversion information, and wherein
• the program execution device comprises:
• a storage unit for storing the distribution program generated by the program conversion device for generating, from one original program, the one distribution program that is executable on the plurality of program execution devices having different security levels;
• an acquiring unit for searching the distribution program to acquire conversion information corresponding to a security level of the program execution device from the distribution program;
• a converting unit, if the conversion information is successfully acquired, for converting the obfuscated program that is included in the distribution program to alter the obfuscation level in accordance with the conversion information, so that a unique program that corresponds to the security level of the program execution device is generated;
• and
• a processor for executing the unique program, wherein
• the generating unit generates the conversion information that indicates conversion to be applied to the obfuscated program to lower the obfuscation level, the converting unit converts the obfuscated program to lower the obfuscation level, and the original program stored in the storage unit includes a sub-program composed of one or more instructions, and
• the obfuscation unit includes:
• a dividing sub-unit for dividing the sub-program into a plurality of partial programs and
• an obfuscating sub-unit for obfuscating the plurality of partial programs to generate a plurality of obfuscated partial programs that together constitute the obfuscated program, wherein
• the generating unit encrypts integration information so that the encrypted integration information is generated, the integration information indicating which of the partial programs are to be integrated, and the output unit outputs the distribution program that includes the plurality of obfuscated partial programs and the encrypted integration information, and wherein
• the acquiring unit decrypts the encrypted integration information acquired as the conversion information, the converting unit, if the encrypted integration information is successfully decrypted, decrypts a plurality of encrypted programs indicated by the decrypted integration information, so that a plurality of partial programs of the unique program are generated, and the processor executes the plurality of partial programs generated, and wherein
• the generating unit encrypts the integration information by using a conversion information key, the acquiring unit decrypts the encrypted integration information by using the conversion information key, the obfuscating sub-unit encrypts each partial program by using a program key, and the converting unit decrypts the encrypted program by using the program key.

A system comprising a program conversion device for generating, from one original program, one distribution program that is executable on a plurality of program execution devices having different security levels, and a program execution device that operates in accordance with a distribution program, wherein

• the program conversion device comprises:
• a storage unit for storing an original program composed of a plurality of computer instructions;
• an obfuscation unit for obfuscating the original program to generate an obfuscated program;
• a generating unit for generating conversion information that indicates conversion to be applied to the obfuscated program so as to alter an obfuscation level correspondingly to one of the security levels;
• and
• an output unit for outputting a distribution program that is composed of the obfuscated program and the conversion information, and wherein
• the program execution device comprises:
• a storage unit for storing the distribution program generated by the program conversion device for generating, from one original program, the one distribution program that is executable on the plurality of program execution devices having different security levels;
• an acquiring unit for searching the distribution program to acquire conversion information corresponding to a security level of the program execution device from the distribution program;
• a converting unit, if the conversion information is successfully acquired, for converting the obfuscated program that is included in the distribution program to alter the obfuscation level in accordance with the conversion information, so that a unique program that corresponds to the security level of the program execution device is generated;
• and
• a processor for executing the unique program, wherein
• the generating unit generates the conversion information that indicates conversion to be applied to the obfuscated program to lower the obfuscation level, the converting unit converts the obfuscated program to lower the obfuscation level, and the original program stored in the storage unit includes a sub-program composed of one or more instructions, and
• the obfuscation unit includes:
• a dividing sub-unit for dividing the sub-program into a plurality of partial programs;
• and
• an encrypting sub-unit for encrypting the plurality of partial programs to generate a plurality of encrypted partial programs that together constitute the obfuscated program, wherein
• the generating unit generates the conversion information by encrypting one or more pieces of integration information by using a security level key that corresponds to a security level, each piece of integration information indicating which of the partial programs are to be integrated, and the output unit outputs the distribution program that includes the plurality of encrypted partial programs and the encrypted integration information, and wherein
• the acquiring unit decrypts the encrypted integration information by using a security level key held by the program execution device, the converting unit, if the encrypted integration information is successfully decrypted, decrypts the plurality of encrypted partial programs indicated by the decrypted integration information, so that a plurality of partial programs are generated as parts of the unique program, and the processor executes the unique program that includes the plurality of partial programs generated.

A system comprising a program conversion device for generating, from one original program, one distribution program that is executable on a plurality of program execution devices having different security levels, and a program execution device that operates in accordance with a distribution program, wherein

• the program conversion device comprises:
• a storage unit for storing an original program composed of a plurality of computer instructions;
• an obfuscation unit for obfuscating the original program to generate an obfuscated program;
• a generating unit for generating conversion information that indicates conversion to be applied to the obfuscated program so as to alter an obfuscation level correspondingly to one of the security levels;
• and
• an output unit for outputting a distribution program that is composed of the obfuscated program and the conversion information, and wherein
• the program execution device comprises:
• a storage unit for storing the distribution program generated by the program conversion device for generating, from one original program, the one distribution program that is executable on the plurality of program execution devices having different security levels;
• an acquiring unit for searching the distribution program to acquire conversion information corresponding to a security level of the program execution device from the distribution program;
• a converting unit, if the conversion information is successfully acquired, for converting the obfuscated program that is included in the distribution program to alter the obfuscation level in accordance with the conversion information, so that a unique program that corresponds to the security level of the program execution device is generated;
• and
• a processor for executing the unique program, wherein
• the generating unit generates the conversion information that indicates conversion to be applied to the obfuscated program to lower the obfuscation level, the converting unit converts the obfuscated program to lower the obfuscation level, and the obfuscation unit inserts a redundant block composed of one or more redundant instructions into the original program, so that the obfuscated program is generated, and wherein
• the generating unit encrypts position information so that encrypted position information is generated as the conversion information, the position information indicating a position in the original program at which the redundant block is inserted, and the output unit outputs the distribution program that includes the encrypted position information and the obfuscated program into which the redundant block is inserted, and wherein
• the acquiring unit decrypts the encrypted position information acquired as the conversion information, the converting unit, if the encrypted position information is successfully decrypted, invalidates one or more instructions of the distribution program stored at a storage location indicated by the decrypted position information, and the processor executes the unique program that includes the one or more invalidated instructions.

A system comprising a program conversion device for generating, from one original program, one distribution program that is executable on a plurality of program execution devices having different security levels, and a program execution device that operates in accordance with a distribution program, wherein

• the program conversion device comprises:
• a storage unit for storing an original program composed of a plurality of computer instructions;
• an obfuscation unit for obfuscating the original program to generate an obfuscated program;
• a generating unit for generating conversion information that indicates conversion to be applied to the obfuscated program so as to alter an obfuscation level correspondingly to one of the security levels;
• and
• an output unit for outputting a distribution program that is composed of the obfuscated program and the conversion information, and wherein
• the program execution device comprises:
• a storage unit for storing the distribution program generated by the program conversion device for generating, from one original program, the one distribution program that is executable on the plurality of program execution devices having different security levels;
• an acquiring unit for searching the distribution program to acquire conversion information corresponding to a security level of the program execution device from the distribution program;
• a converting unit, if the conversion information is successfully acquired, for converting the obfuscated program that is included in the distribution program to alter the obfuscation level in accordance with the conversion information, so that a unique program that corresponds to the security level of the program execution device is generated;
• and
• a processor for executing the unique program, wherein
• the generating unit generates the conversion information that indicates conversion to be applied to the obfuscated program to lower the obfuscation level, the converting unit converts the obfuscated program to lower the obfuscation level, and the obfuscation unit inserts a check program for detecting any tampering with the original program into the original program, so that the obfuscated program is generated, and wherein
• the generating unit encrypts check information that includes position information and an invalidated program, so that the conversion information is generated, the position information indicating a position in the original program at which the check program is inserted, and the invalidated program being an invalidated version of the check program causing no checking operation to be performed, and the output unit outputs the distribution program that includes the encrypted check information and the obfuscated program into which the check program is inserted, and wherein
• the acquiring unit decrypts the encrypted check information acquired as the conversion information, the generating unit, if the encrypted check information is successfully decrypted, replaces one or more instructions of the distribution program stored at a storage location indicated by the decrypted position information with the invalidated program included in the generated check information, and the processor executes the unique program that includes the invalidated program.

A program execution method for use by a program execution device that operates in accordance with a distribution program generated by a program conversion device that generates, from one original program, one distribution program that is executable on a plurality of program execution devices having different security levels, wherein

• the program conversion device comprises:
• a storage unit for storing an original program composed of a plurality of computer instructions;
• an obfuscation unit for obfuscating the original program to generate an obfuscated program;
• a generating unit for generating conversion information that indicates a conversion to be applied to the obfuscated program so as to alter an obfuscation level correspondingly to one of the security levels;
• and
• an output unit for outputting a distribution program that is composed of the obfuscated program and the conversion information, wherein the conversion information indicates that the alteration to be applied to the obfuscation level of the obfuscated program is to lower the obfuscation level, and wherein
• the program execution method comprises:
• an acquiring step of searching using an acquiring unit the distribution program to acquire conversion information corresponding to a security level of the program execution device from the distribution program;
• a converting step of converting using a converting unit, if the conversion information is successfully acquired, the obfuscated program that is included in the distribution program to alter the obfuscation level in accordance with the conversion information, so that a unique program that corresponds to the security level of the program execution device is generated;
• and
• a processing step of executing using a processor the unique program, wherein
• the generating unit generates the conversion information that indicates conversion to be applied to the obfuscated program to lower the obfuscation level, the converting unit converts the obfuscated program to lower the obfuscation level, and the original program stored in the storage unit includes a sub-program composed of one or more instructions, and
• the obfuscation unit includes:
• a dividing sub-unit for dividing the sub-program into a plurality of partial programs and
• an obfuscating sub-unit for obfuscating the plurality of partial programs to generate a plurality of obfuscated partial programs that together constitute the obfuscated program, and wherein
• the generating unit encrypts integration information so that encrypted integration information is generated, the integration information indicating which of the partial programs are to be integrated, and the output unit outputs the distribution program that includes the plurality of obfuscated partial programs and the encrypted integration information, and wherein
• the acquiring unit decrypts the encrypted integration information acquired as the conversion information, the converting unit, if the encrypted integration information is successfully decrypted, decrypts a plurality of encrypted programs indicated by the decrypted integration information, so that a plurality of partial programs of the unique program are generated, and the processor executes the plurality of partial programs generated, and wherein
• the generating unit encrypts the integration information by using a conversion information key, the acquiring unit decrypts the encrypted integration information by using the conversion information key, the obfuscating sub-unit encrypts each partial program by using a program key, and the converting unit decrypts the encrypted program by using the program key.

A non-transitory computer-readable storage medium storing a program-execution program for use by a program execution device that operates in accordance with a distribution program generated by a program conversion device that generates, from one original program, one distribution program that is executable on a plurality of program execution devices having different security levels, wherein

• the program conversion device comprises:
• a storage unit for storing an original program composed of a plurality of computer instructions;
• an obfuscation unit for obfuscating the original program to generate an obfuscated program;
• a generating unit for generating conversion information that indicates a conversion to be applied to the obfuscated program so as to alter an obfuscation level correspondingly to one of the security levels;
• and
• an output unit for outputting a distribution program that is composed of the obfuscated program and the conversion information, wherein the conversion information indicates that the alteration to be applied to the obfuscation level of the obfuscated program is to lower the obfuscation level, and wherein
• the program-execution program comprises code that causes the program execution device to perform:
• an acquiring step of searching using an acquiring unit the distribution program to acquire conversion information corresponding to a security level of the program execution device from the distribution program;
• a converting step of converting using a converting unit, if the conversion information is successfully acquired, the obfuscated program that is included in the distribution program to alter the obfuscation level in accordance with the conversion information, so that a unique program that corresponds to the security level of the program execution device is generated;
• and
• a processing step of executing using a processor the unique program, wherein
• the generating unit generates the conversion information that indicates conversion to be applied to the obfuscated program to lower the obfuscation level, the converting unit converts the obfuscated program to lower the obfuscation level, and the original program stored in the storage unit includes a sub-program composed of one or more instructions, and
• the obfuscation unit includes:
• a dividing sub-unit for dividing the sub-program into a plurality of partial programs and
• an obfuscating sub-unit for obfuscating the plurality of partial programs to generate a plurality of obfuscated partial programs that together constitute the obfuscated program, and
• wherein the generating unit encrypts integration information so that encrypted integration information is generated, the integration information indicating which of the partial programs are to be integrated, and the output unit outputs the distribution program that includes the plurality of obfuscated partial programs and the encrypted integration information, and wherein
• the acquiring unit decrypts the encrypted integration information acquired as the conversion information, the converting unit, if the encrypted integration information is successfully decrypted, decrypts a plurality of encrypted programs indicated by the decrypted integration information, so that a plurality of partial programs of the unique program are generated, and the processor executes the plurality of partial programs generated, and wherein
• the generating unit encrypts the integration information by using a conversion information key, the acquiring unit decrypts the encrypted integration information by using the conversion information key, the obfuscating sub-unit encrypts each partial program by using a program key, and the converting unit decrypts the encrypted program by using the program key.

An integrated circuit that operates in accordance with a distribution program generated by a program conversion device that generates, from one original program, one distribution program that is executable on a plurality of program execution devices having different security levels, wherein

• the program conversion device comprises:
• a storage unit for storing an original program composed of a plurality of computer instructions;
• an obfuscation unit for obfuscating the original program to generate an obfuscated program;
• a generating unit for generating conversion information that indicates a conversion to be applied to the obfuscated program so as to alter an obfuscation level correspondingly to one of the security levels;
• and
• an output unit for outputting a distribution program that is composed of the obfuscated program and the conversion information, wherein the conversion information indicates that the alteration to be applied to the obfuscation level of the obfuscated program is to lower the obfuscation level, and wherein
• the integrated circuit comprises:
• a storage unit for storing the distribution program generated by the program conversion device;
• an acquiring unit for searching the distribution program to acquire conversion information corresponding to a security level of the program execution device from the distribution program;
• a converting unit, if the conversion information is successfully acquired, for converting the obfuscated program that is included in the distribution program to alter the obfuscation level in accordance with the conversion information, so that a unique program that corresponds to the security level of the program execution device is generated;
• and
• a processor for executing the unique program, wherein
• the generating unit generates the conversion information that indicates conversion to be applied to the obfuscated program to lower the obfuscation level, the converting unit converts the obfuscated program to lower the obfuscation level, and the original program stored in the storage unit includes a sub-program composed of one or more instructions, and
• the obfuscation unit includes:
• a dividing sub-unit for dividing the sub-program into a plurality of partial programs and an obfuscating sub-unit for obfuscating the plurality of partial programs to generate a plurality of obfuscated partial programs that together constitute the obfuscated program, and wherein
• the generating unit encrypts integration information so that encrypted integration information is generated, the integration information indicating which of the partial programs are to be integrated, and the output unit outputs the distribution program that includes the plurality of obfuscated partial programs and the encrypted integration information, and wherein
• the acquiring unit decrypts the encrypted integration information acquired as the conversion information, the converting unit, if the encrypted integration information is successfully decrypted, decrypts a plurality of encrypted programs indicated by the decrypted integration information, so that a plurality of partial programs of the unique program are generated, and the processor executes the plurality of partial programs generated, and wherein
• the generating unit encrypts the integration information by using a conversion information key, the acquiring unit decrypts the encrypted integration information by using the conversion information key, the obfuscating sub-unit encrypts each partial program by using a program key, and the converting unit decrypts the encrypted program by using the program key.

A system having (i) a program conversion device for generating, from one original program, one distribution program that is executable on a plurality of program execution devices having different security levels and (ii) a program execution device that operates in accordance with a distribution program,

• the program conversion device comprising:
• a storage unit for storing an original program composed of a plurality of computer instructions;
• an obfuscation unit for obfuscating the original program to generate an obfuscated program;
• a generating unit for generating conversion information that indicates conversion to be applied to the obfuscated program so as to alter an obfuscation level correspondingly to one of the security levels;
• and
• an output unit for outputting a distribution program that is composed of the obfuscated program and the conversion information, and
• the program execution device comprising:
• a storage unit for storing the distribution program generated by the program conversion device;
• an acquiring unit for searching the distribution program to acquire conversion information corresponding to a security level of the program execution device from the distribution program;
• a converting unit operable, if the conversion information is successfully acquired, to convert the obfuscated program that is included in the distribution program to alter the obfuscation level in accordance with the conversion information, so that a unique program that corresponds to the security level of the program execution device is generated;
• and
• a processor for executing the unique program.

A system having (i) a program conversion device for generating, from one original program, one distribution program that is executable on a plurality of program execution devices having different security levels and (ii) a program execution device that operates in accordance with a distribution program,

• the program conversion device comprising:
• a storage unit for storing an original program composed of a plurality of computer instructions;
• an obfuscation unit for obfuscating the original program to generate an obfuscated program;
• a generating unit for generating conversion information that indicates conversion to be applied to the obfuscated program so as to alter an obfuscation level correspondingly to one of the security levels;
• and
• an output unit for outputting a distribution program that is composed of the obfuscated program and the conversion information, and
• the program execution device comprising:
• a storage unit for storing the distribution program generated by the program conversion device;
• an acquiring unit for searching the distribution program to acquire conversion information corresponding to a security level of the program execution device from the distribution program;
• a converting unit operable, if the conversion information is successfully acquired, to convert the obfuscated program that is included in the distribution program to alter the obfuscation level in accordance with the conversion information, so that a unique program that corresponds to the security level of the program execution device is generated;
• and
• a processor for executing the unique program, wherein
• the generating unit generates the conversion information that indicates conversion to be applied to the obfuscated program to lower the obfuscation level, the converting unit converts the obfuscated program to lower the obfuscation level, and the original program stored in the storage unit includes a sub-program composed of one or more instructions, and
• the obfuscation unit includes:
• a dividing sub-unit for dividing the sub-program into a plurality of partial programs and
• an obfuscating sub-unit for obfuscating the plurality of partial programs to generate a plurality of obfuscated partial programs that together constitute the obfuscated program, and wherein
• the generating unit encrypts integration information so that encrypted integration information is generated, the integration information indicating which of the partial programs are to be integrated, and the output unit outputs the distribution program that includes the plurality of obfuscated partial programs and the encrypted integration information, and wherein
• the acquiring unit decrypts the encrypted integration information acquired as the conversion information, the converting unit, if the encrypted integration information is successfully decrypted, decrypts a plurality of encrypted programs indicated by the decrypted integration information, so that a plurality of partial programs of the unique program are generated, and the processor executes the plurality of partial programs generated, and wherein
• the generating unit encrypts the integration information by using a conversion information key, the acquiring unit decrypts the encrypted integration information by using the conversion information key, the obfuscating sub-unit encrypts each partial program by using a program key, and the converting unit decrypts the encrypted program by using the program key.