The Autocorrelation, the Spectrum, and Phase Retrieval

Tharrmashastha Sapv, Debajyoti Bera, Arpita Maitra +1 more

Debajyoti Bera, Subhamoy Maitra, Tharrmashastha Sapv

Debajyoti Bera, Subhamoy Maitra, Tharrmashastha Sapv

Meihua Liao, Dajiang Lu, Wenqi He +1 more

The speckle correlation technique is applied to ciphertext-only attack (COA) on optical cryptosystem based on double random phase encoding. According to the inherent merits of speckle correlation, we have revealed a fact that the ciphertext’s autocorrelation is essentially identical to the plaintext’s own autocorrelation. Then, a plaintext image can be directly reconstructed from the autocorrelation of its corresponding ciphertext by employing a iterate phase-retrieval algorithm. This could then lead to a potential security flaw because an unauthorized user could directly retrieve the plaintext from an intercepted ciphertext by performing proposed COA approach. Meanwhile, a series of numerical simulations will also be provided to verify the validity and feasibility of our proposed COA method.

E. Wolf

Xiao A. Shen, R. Hartman, Ravinder Kachru

We propose a novel approach to time-domain storage of serial optical data. In this approach, two identical impulse-equivalent sequences are used as write and read pulses to store and later retrieve optical information. These pulse sequences are both amplitude and phase modulated in such a way that their autocorrelations resemble, as closely as theoretically possible, the autocorrelation of a single large brief pulse to ensure faithful data retrieval. Such impulse-equivalent sequences are known to exist for all lengths, permitting the storage of large-bandwidth data. The advantages of this approach include modest laser power requirement, high signal fidelity, and encrypted recording.