Pipelined Statistical Cipher Feedback: A New Mode for High-Speed Self-Synchronizing Stream Encryption

Abstract

-In this paper, we introduce a new block cipher mode of operation targeted to providing high speed hardware-based self-synchronizing stream encryption. The proposed mode is a modification of statistical cipher feedback (SCFB) mode and is designed to be implemented using pipeline architectures for the block cipher. We refer to the mode as pipelined SCFB mode or PSCFB. In this paper, we consider the implementation characteristics and show that PSCFB is able to achieve speeds that are very close to pipelined block cipher implementations configured for counter mode. Such speeds are achieved with modest latency through the system and a small amount of memory required for the system queues with a provable guarantee of no queue overflow. Further, we examine the characteristics of PSCFB mode in response to bit errors and synchronization losses in the communication channel. Specifically, we show that the error propagation factor is modest and comparable to conventional SCFB and that synchronization recovery delay is reasonable given the expectation that synchronization loss is infrequent. Given the high efficiency and good communication characteristics of the mode, it is concluded that PSCFB is an excellent choice for high speed network applications requiring stream-oriented encryption with self-synchronizing capabilities.

Overview of securing multimedia content using efficient encryption methods and modes

“…It provides automatic resynchronization by modifying block cipher as a stream cipher, which is self-synchronizing (Heys and Zhang, 2011).…”

Hardware implementation of a high speed self-synchronizing cipher mode

“…Based on the proposed structure in [2] and illustrated in Fig. 3, a plaintext queue and ciphertext queue are two significant parts which can affect the speed of the PSCFB system.…”

“…The minimum size of plaintext and ciphertext queue is M = B + 3D − 2 = 444, with B = 128 and input rate D = 116 [2]. This provides the maximum efficiency of D/B = 90.625% without any overflow in the plaintext queue or underflow in the ciphertext queue.…”

“…Pipelined statistical cipher feedback (PSCF-B) [2] mode uses a pipeline architecture in the block cipher based on counter (CTR) mode. In this paper, AES [3] in PSCFB mode with a 128 bit key is used as the block cipher to generate keystream.…”

Error burst analysis of a statistical self-synchronizing mode of block ciphers

“…Further, although SCFB mode is modified from the conventional mode of cipher feedback (CFB) , it is shown in to be much more efficient to apply than CFB, resulting in much higher throughputs for a hardware‐based implementation of a block cipher such as the Advanced Encryption Standard (AES) . In fact, it can be shown that SCFB mode and the derived mode of pipelined SCFB (PSCFB) can approach efficiencies of 100%. In contrast, conventional CFB mode, when implemented to recover from any size of data loss in the channel, has an efficiency of less than 1% when used with AES.…”