光学加密技术研究进展
时间：2021-04-28 16:18:28 来源：星星阅读网 本文已影响 人 
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Abstract： Optical techniques have shown great potential in information security.This paper reviews the most recent technological and application advances of optical encryption of 2D and 3D objects.The main optical encryption techniques and encryption algorithms are summarized and illustrated in detail.Challenges and developments，which are the subject of the contributions to this focus paper，are also discussed，and prospects are predicted.
Key words： information security； optical encryption； random phase； digital holography
1 Introduction
With the rapid development of internet and modern communications techniques，information security has become a serious problem.Optical encryption techniques have attracted significant interest and emerged as one type of the most important means for information security.Optical system offers the possibility of highspeed parallel processing and provides many degrees of freedom to handle parameters such as the amplitude，phase，wavelength，and polarization of the light wave[1].So recent progress in the development of optical components and systems and their increasingly improved technical performance suggest that optical encryption has significant potential for security applications.Indeed，many optical security systems and methods have been proposed to protect the information and information transmission[2-5].
A typical optical encryption system employs two random phase masks introduced in the spatial and Fourier planes in a standard 4f coherent optical system[6].Such a doublerandom phase encoding （DRPE） technique is to convert a primary image into a stationary white noise by the two independent random phase masks.However，the technique is prone to impulse attacks[7].Recently，many schemes to improve the DRPE have been investigated，such as using the fractional Fourier transform[8]，Fresnel transform[9]，Gyrator transform[10]，linear canonical transform[11]，Hartley transform[12]，fractional Mellin transform[13]，joint transform correlation[14]，excusiveOR encryption[15]，etc.Theoretical and experimental results have indicated that the performances of optical encryption systems using the DRPE can be enhanced significantly using these methods.
Because the accurate extraction of a complex field is important for image decryption，digital holography has been proposed in optical encryption system[16].Recently，several types of holography，i.e.，offaxis digital holography，phaseshifting digital holography[17-18]，and optical scanning holography[19-20]，have been developed.It was shown that 2D images encrypted by doublerandom phase encoding could be recorded in digital holography.Holograms of 2D images or 3D objects can be encrypted with phaseshifting digital holography by means of inserting a phase mask in one of the paths of the signal or the reference beam[21-22].It is also well known that digital holography is an effective method to encrypt 3D objects and information.Many other schemes to encrypt 3D objects have been proposed，including virtual optics[23]，fringe projection encoding[24]，and diffractive imaging[25].
