RESUMO

We introduce for the first time the concept of an information "container" before a standard optical encrypting procedure. The "container" selected is a QR code which offers the main advantage of being tolerant to pollutant speckle noise. Besides, the QR code can be read by smartphones, a massively used device. Additionally, QR code includes another secure step to the encrypting benefits the optical methods provide. The QR is generated by means of worldwide free available software. The concept development probes that speckle noise polluting the outcomes of normal optical encrypting procedures can be avoided, then making more attractive the adoption of these techniques. Actual smartphone collected results are shown to validate our proposal.

RESUMO

In this Letter, we present to the best of our knowledge a new all-optical technique for multiple-image encryption and multiplexing, based on fractal encrypting masks. The optical architecture is a joint transform correlator. The multiplexed encrypted data are stored in a photorefractive crystal. The fractal parameters of the key can be easily tuned to lead to a multiplexing operation without cross talk effects. Experimental results that support the potential of the method are presented.

RESUMO

In experimental optodigital encrypting architectures, the use of a reference wave is essential. In this contribution, we present an experimental alternative to avoid the reference wave during the encrypting procedure in a joint transform correlator architecture by introducing the concept of a master key. Besides, the master key represents an additional security element for the entire protocol. In our method, the master key is holographically processed and used during the encryption process with the encrypting key. We give the mathematical description for the process in case of a single input object and then we extend it to multiple input objects. We present the experimental demonstration of the proposed method including two examples where this technique is successfully applied for several input objects.

RESUMO

We present the first experimental technique to encrypt a movie under a joint transform correlator architecture. We also extend the method to multiplex several movies in a single package. We use a Mach-Zehnder interferometer to encrypt experimentally each movie. One arm of the interferometer is the joint transform correlator and the other arm is the reference wave. We include the complete description of the procedure along with experimental results supporting the proposal.

RESUMO

We demonstrate a smart image-packaging optical technique that uses what we believe is a new concept to save byte space when transmitting data. The technique supports a large set of images mapped into modulated speckle patterns. Then, they are multiplexed into a single package. This operation results in a substantial decreasing of the final amount of bytes of the package with respect to the amount resulting from the addition of the images without using the method. Besides, there are no requirements on the type of images to be processed. We present results that proof the potentiality of the technique.

Assuntos

RESUMO

We introduce a way to encrypt-decrypt a color dynamical phenomenon using a pure optical alternative. We split the three basic chromatic channels composing the input, and then each channel is processed through a 4f encoding method and a theta modulation applied to the each encrypted frame in every channel. All frames for a single channel are multiplexed. The same phase mask is used to encode all the information. Unlike the usual procedure we do not multiplex the three chromatic channels into a single encoding media, because we want to decrypt the information in real time. Then, we send to the decoding station the phase mask and the three packages each one containing the multiplexing of a single channel. The end user synchronizes and decodes the information contained in the separate channels. Finally, the decoding information is conveyed together to bring the decoded dynamical color phenomenon in real-time. We present material that supports our concepts.

RESUMO

We introduce for the first time the concept of an all-optical encrypted movie. This movie joints several encrypted frames corresponding to a time evolving situation employing the same encoding mask. Thanks to a multiplexing operation we compact the encrypted movie information into a single package. But the decryption of this single package implies the existence of cross-talk if we do not adequately pre-process the encoded information before multiplexing. In this regard, we introduce a grating modulation to each encoded image, and then we proceed to multiplexing. After appropriate filtering and synchronizing procedures applied to the multiplexing, we are able to decrypt and to reproduce the movie. This movie is only properly decoded when in possession of the right decoding key. The concept development is carried-out in virtual optical systems, both for the encrypting and the filtering-decrypting stages. Experimental results are shown to confirm our approach.

RESUMO

We demonstrate in this Letter that a joint transform correlator shows vulnerability to known-plaintext attacks. An unauthorized user, who intercepts both an object and its encrypted version, can obtain the security key code mask. In this contribution, we conduct a hybrid heuristic attack scheme merge to a Gerchberg-Saxton routine to estimate the encrypting key to decode different ciphertexts encrypted with that same key. We also analyze the success of this attack for different pairs of plaintext-ciphertext used to get the encrypting code. We present simulation results for the decrypting procedure to demonstrate the validity of our analysis.

RESUMO

We present a method that allows storing multiple encrypted data using digital holography and a joint transform correlator architecture with a controllable angle reference wave. In this method, the information is multiplexed by using a key and a different reference wave angle for each object. In the recovering process, the use of different reference wave angles prevents noise produced by the nonrecovered objects from being superimposed on the recovered object; moreover, the position of the recovered object in the exit plane can be fully controlled. We present the theoretical analysis and the experimental results that show the potential and applicability of the method.

RESUMO

Objects acting as inputs of encrypting optical systems can be regarded as having two independent channels: amplitude and phase. In this context, we can use the term "complex objects" to refer these input objects. In this work we explore the way to perform an undercover operation where one channel (amplitude) is used to depict decoy information to confuse intruders, while the other (phase) operates with the true information. Besides, we use the Gerchberg-Saxton algorithm to transform the amplitude and phase encrypted information into pure phase data, therefore increasing the efficiency of the technique as only a single matrix containing these data needs to be sent. Finally, as an example to show the potential of the method, we combine the separate channels in a multiplexing technique with the Gerchberg-Saxton algorithm to generate an efficient multiuser secure process.

RESUMO

We show that multiple secure data recording under a wavelength multiplexing technique is possible in a joint transform correlator (JTC) arrangement. We evaluate both the performance of the decrypting procedure and the influence of the input image size when decrypting with a wavelength different from that employed in the encryption step. This analysis reveals that the wavelength is a valid parameter to conduct image multiplexing encoding with the JTC architecture. In addition, we study the influence of the minimum wavelength change that prevents decoding cross talk. Computer simulations confirm the performance of the proposed technique.

RESUMO

We propose the use of fractal structured diffractive masks as keys in secure storage-readout systems. A joint transform correlator based on a photorefractive crystal in the Fourier domain is implemented to perform encryption and decryption. We discuss the advantages of encrypting information using this kind of deterministic keys in comparison to conventional random phase masks. Preliminary experimental results are presented to demonstrate the effectiveness of the proposed system.

RESUMO

We analyze the dual random phase encoding technique in the temporal domain to evaluate its potential application for secure data transmission in fiber optic links. To take into account the optical fiber multiplexing capabilities, the noise content of the signal is restricted when multiple channels are transmitted over a single fiber optic link. We also discuss some mechanisms for producing encoded time-limited as well as bandwidth-limited signals and a comparison with another recently proposed technique is made. Numerical simulations have been carried out to analyze the system performance. The results indicate that this multiplexing encryption method could be a good alternative compared with other well-established methods.

RESUMO

We propose a multichanneling encryption method by using multiple random-phase mask apertures in the input plane based on a joint transform correlation scheme. In the proposal, this multiple aperture arrangement is changed as different input objects are inserted and stored. Then, during the decryption step, the appropriate use of the random-phase mask apertures can ensure the retrieval of different information. This approach provides different access levels. Computer simulations show the potential of the technique and experimental results verify the feasibility of this method.