Golden Fish: An Intelligent Stream Cipher Fuse Memory Modules

In this paper, we use a high-order iterated function generated by block cipher as the nonlinear filter to improve the security of stream cipher. Moreover, by combining the published rounds function in block cipher and OFB as the nonlinear functional mode with an extra memory module, we enable to control the nonlinear complexity of the design. This new approach fuses the block cipher operation mode with two memory modules in one stream cipher. The security of this design is proven by the both periodic and nonlinear evaluation. The periods of this structure is guaranteed by the traditional Linear Feedback Shift Register design and the security of nonlinear characteristic is demonstrated by block cipher algorithm design itself, which is remarkably safer than the previous designs of stream cipher. We also can find such design style at SHA3.