Cryptoanalysis On The Random Phase And Polarization Encoding Encryption System

In the big data era,traditional information security technology based on mathematical principles is far from meeting people's needs,so it is necessary to develop some faster and more secure information security technologies.Optical information security technology is one of the new information security technologies developed in recent years.In last decade,scholars in this area have proposed various optical encryption methods.It is an important research direction to analyze the security of these encryption systems and apply them.Each optical encryption system should be subject to a rigorous and comprehensive cryptographic analysis before it is applied to practice.Cryptographic analysis of optical encryption systems has great value both in the practical applications and the integrity of the information security theory.Most optical encryption systems are symmetric cryptosystems.The input and output of such systems have a strong linear relationship and are easily cracked by various attack algorithms.A novel cyphertext-only attack on the optical encryption system based on the joint transform correlator architecture is proposed.In this method,we can split the cyphertext into many small sub-images,calculate the autocorrelation of each subimage and average them out to generate an estimation of the plaintext's energy spectral density by using the imaging correlation method,then reconstruct the plaintext information by using a phase retrieval algorithm.The reconstructed plaintext information has a high correlation coefficient with the original plaintext.Compared with the existing cyphertext-only attack method on this encryption system,our method requires less resources and is therefore more valuable.We also make a cyphertext-only attack on the cyphertext obtained by experiment,this is the first experimental analysis of cyphertext-only attack to the optical encryption system based on the joint transform correlator architecture.A novel chosen-plaintext attack on the double random polarization encoding encryption system is proposed.In this method,we find that there is a strong linear relationship between the plaintexts and the cyphertexts by analyzing the encryption system.We choose two special polarization states as plaintexts information,and get the corresponding cyphertexts.We can get a set of equations containing parameters of the key in the Fourier plane by simplifying the equations of the encryption process.Then we calculate the key in the Fourier plane by solving the equations,and the key in the input plane can be further derived.So that we can use the keys to recover more plaintextinformation.Our research is the first cryptographic analysis on the double random polarization encoding encryption system.Cryptographic analysis shows that these two types of optical encryption systems have serious security risks and need to be considered when designing new optical encryption systems.