| 摘要 |
PURPOSE: An encryption apparatus and method using a CTR(counter) mode of an advanced encryption standard are provided to reduce a series of calculation of an AES algorithm by referring to three states which are stored in a cache. CONSTITUTION: An inputted plane text is divided into a target data block having a size of 128 bits(310). An initialization vector is divided into four 4 byte states. A first cipher text is generated through XOR about encrypted results(320) Three states having a value which is not changed among the four divided states are stored in a cache(330). The N number of the cipher texts is generated by performing the XOR operation of operation results which are obtained with reference to each block and cache about the N number of blocks which is sequent to a first block(340). The first cipher text and the N number of cipher texts are outputted as an encryption result(350). [Reference numerals] (310) Receiving a plane text and dividing the plane text into a target data block having a size of 128 bits, receiving the 128 bit data block for each round and setting the 128 bit data block as an initial vector, and dividing the initial vector into four 4byte states; (320) Generating a first cipher text through the XOR of encrypted results using the initial vector and a first block from the divided target data block; (330) Storing three states having a value which is not changed during a calculation process in each round among the four divided states in a cache; (340) Generating the N number of the cipher texts by performing the XOR operation of the operation results with reference to each block and cache about the N number of blocks which is sequent to a first block; (350) Outputting the first cipher text and the N number of cipher texts as an encryption result; (AA) Start; (BB) End
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