Academy & Industry Research Collaboration Center
It has been shown that the encrypted information or cipher-text produced by symmetric-key block ciphers with Electronic codebook mode is vulnerable to cipher-text searching, replay, insertion and deletion because it encrypts each block independently. To compensate for this, each block of the encrypted information should be encrypted dependently. The encrypted information should be operated with a special mode. The operation mode should be changed. This paper analysis what an operational mode of block ciphers needs to feedback exactly and proposes a simple real-time changing operation mode technique that extends the existing mode changing opportunity. The new change operation mode technique considers the sign differences between the intra-feedback information and the public-feedback information, and then adaptively determines the corresponding change operation mode factor for each data block.