Building a block cipher mode of operation with feedback keys

In this paper, we propose two block cipher modes of operation (BCMO for short), named the Key Stream Protection Chain mode (KSPC for short) and Output Dual Chaining mode (ODC for short), which differ from other existing BCMOs in that in the KSPC, the ciphertext block and in the ODC, the block cipher encryption unit´s output are fed back to the encryption system to be one of the inputs of the next block ciphering. We also evaluate three existing BCMOs, including the Cipher Block Chaining mode (CBC), the Propagating Cipher Block Chaining mode (PCBC) and the Output Feedback mode (OFB), and discuss the security of the these modes when they face chosen-plaintext attacks. At last, we explain why our new BCMOs´ security levels are higher than those of the existing three.