Blind Recovery of Initial Parameters of Scrambler

In the non-cooperation communication, an eavesdropper didn’t have all parameters. In order to estimate the initial parameters of scrambler, we had to correct the transmission errors and to recover the feedback polynomial and initial state of scrambler. With the property of dual word and technique of multiple streams anti-interference, we generated a new sequence of low-error probability that contained the parameters of scrambler. According to low-weight multiple searching algorithm and fast correlation attacks based on convolutional code, we reconstructed the feedback polynomial and initial state of the new generated sequence. Finally, we recovered the initial parameters of scrambler by the relationship between the new sequence and scrambling sequence. The simulation results verify the efficiency of the reconstruction method that can eliminate the noise interference effectively when the signal-to-noise ratio is 0 dB.