中圖分類號： TP309.7
文獻標識碼： A
DOI： 10.19358/j.issn.2096-5133.2022.06.004
引用格式： 張玉安，王野，漆駿鋒，等. 保留格式加密的雙擾工作模式[J].信息技術與網(wǎng)絡安全，2022，41(6)：22-25，35.

Two-time scrambling mode of FPE schemes

Abstract： Small block sizes may lead to the information leakage of plaintext due to the cipher block repetition in the block cipher′s ECB or CBC mode. This paper presents an innovative block cipher mode for format preserving encryption. Firstly, encrypting an initialization vector as the start point, and then generating the unpredictable sequence by the method of user key functioned nonlinear recursion. By scrambling, the sequence is functioned into the input and the output before and after the block iterative-transformation. The process of transforming the original plaintext into the ciphertext consists of three steps：plaintext scrambling, block cipher encryption and ciphertext scrambling. This makes it difficult for attackers to obtain and accumulate plaintext-ciphertext pairs, as well as to carry out any known-plaintext attacks. To a great extent, this will eliminate the security defects that may arise from the smaller space of plaintext blocks by using a certain block cipher scheme. Therefore, this mode applies to some FPE algorithms or lightweight cipher schemes with smaller block sizes.

Key words : block cipher modes；format preserving encryption；plaintext-ciphertext scrambling