1. A program obfuscating apparatus which obfuscates an information security program instructing execution of a security operation that processes target information securely and reliably with use of key information, the program obfuscating apparatus comprising: an acquisition unit operable to acquire the information security program in which a plurality of basic operations are placed in an order determined by the key information such that an operation result of the plurality of basic operations is equivalent to an operation result of the security operation, the plurality of basic operations being one or more first basic operations and one or more second basic operations, each of the first basic operations requiring a plurality of inputs, and each of the second basic operations requiring only part of the plurality of inputs; a transformation unit operable to place an input dependent conversion operation and an input dependent inverse conversion operation before and after each of the second basic operations, respectively, the input dependent conversion operation depending on, among the plurality of inputs, one or more inputs unrequired for the second basic operation, and the input dependent inverse conversion operation being an inverse conversion of the input dependent conversion operation; a table generating unit operable to, for each of the second basic operations, (i) generate a table which yields an operation result equivalent to an operation result of a set of operations including the input dependent conversion operation placed immediately before the second basic operation, the second basic operation, and the input dependent inverse conversion operation placed immediately after the second basic operation, and (ii) generate a reference instruction to refer to the table; and an output unit operable to output an obfuscated program including the generated tables and the generated reference instructions.