We show how optical encryption methods based on double random phase keys are vulnerable to an organized attack of the chosen-ciphertext type. The decryption key can be easily obtained by an opponent who has repeated access to either the encryption or decryption machines. However, we have also devised a solution that prevents the attack. Our results cast doubts on the present security of these techniques.
"The first three attacks need to know some available resources in advance, e.g. some pairs (or one pair) of designed plaintexts (like impulse functions) and the corresponding ciphertexts, which have been reported in    to attack DRPEs. The motivation of the above attacks is to decipher the decryption keys and then use them to decode other ciphertexts encoded by the same keys. "
[Show abstract][Hide abstract] ABSTRACT: We report a simultaneous image compression and encryption scheme based on solving a typical optical inverse problem. The secret images to be processed are multiplexed as the input intensities of a cascaded diffractive optical system. At the output plane, a compressed complex-valued data with a lot fewer measurements can be obtained by utilizing error-reduction phase retrieval algorithm. The magnitude of the output image can serve as the final ciphertext while its phase serves as the decryption key. Therefore the compression and encryption are simultaneously completed without additional encoding and filtering operations. The proposed strategy can be straightforwardly applied to the existing optical security systems that involve diffraction and interference. Numerical simulations are performed to demonstrate the validity and security of the proposal.
Journal of optics 12/2015; 17(12). DOI:10.1088/2040-8978/17/12/125701 · 2.06 Impact Factor
"It allows to break the data encrypted with DRPE for a satisfactory time. The analysis of the cryptographic security of the DRPE method was performed in the works [Carnicer et al. (2005); Peng, Wei et al. (2006); Peng et al. (2007); Peng, Zhang et al. (2006); Frauel et al. (2007); Qin, Peng (2009); Qin, He et al. (2009)]. "
[Show abstract][Hide abstract] ABSTRACT: Known techniques of breaking Double Random Phase Encoding (DRPE), which bypass the resource-intensive brute-force method, require at least two conditions: the attacker knows the encryption algorithm; there is an access to the pairs of source and encoded images. Our numerical results show that for the accurate recovery by numerical brute-force attack, someone needs only some a priori information about the source images, which can be quite general. From the results of our numerical experiments with optical data encryption DRPE with digital holography, we have proposed four simple criteria for guaranteed and accurate data recovery. These criteria can be applied, if the grayscale, binary (including QR-codes) or color images are used as a source.
4th International Conference of Photonics and Information Optics, PhIO, Moscow, Russian Federation; 10/2015
"On the other hand, in practice, the encryption algorithms can also be realized and implemented in digital forms. In such scenarios, the conventional optical encryption system has shown to be vulnerable to some formulated attacks       . "
[Show abstract][Hide abstract] ABSTRACT: In this study, we investigate the integration of compressive sensing (CS) and photon-counting imaging (PCI) techniques with a ptychography-based optical image encryption system. Primarily, the plaintext real-valued image is optically encrypted and recorded via a classical ptychography technique. Further, the sparse-based representations of the original encrypted complex data can be produced by combining CS and PCI techniques with the primary encrypted image. Such a combination takes an advantage of reduced encrypted samples (i.e., linearly projected random compressive complex samples and photon-counted complex samples) that can be exploited to realize optical decryption, which inherently serves as a secret key (i.e., independent to encryption phase keys) and makes an intruder attack futile. In addition to this, recording fewer encrypted samples provides a substantial bandwidth reduction in online transmission. We demonstrate that the fewer sparse-based complex samples have adequate information to realize decryption. To the best of our knowledge, this is the first report on integrating CS and PCI with conventional ptychography-based optical image encryption.
Journal of optics 06/2015; 17(6). DOI:10.1088/2040-8978/17/6/065704 · 2.06 Impact Factor
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