An Efficient Hash Based Parallel Block Cipher Mode of Operation

Abstract

Block cipher encryption works on fixed length blocks, usually 128bits. The blocks of data are transformed into encrypted data blocks of identical size using a shared session key. A common feature of some modes of block cipher, such as Cipher Block Chaining mode (CBC), Cipher Feedback mode (CFB), Output Feedback mode (OFB), is the sequential processing. The ciphering process of a block cannot begin until the processing of the preceding block is completed. This feature does not make full use of the processing power in multiple processor systems. In this paper, we proposed a Parallel Block Cipher (PBC) mode, in which blocks of cipher can be processed in parallel. Results of speed performance tests of the PBC mode using various settings are presented and compared with the standard CBC mode. The PBC mode was shown to save 60% of execution time when compared with the CBC mode. Furthermore, the hash value of the data file might be utilized to provide integrity check in addition to encryption using AES128. As a result, the PBC mode has a better speed performance on top of the confidentiality and security provided by the CBC mode.