Systems and methods performed for generating authentication information for an image using optical computing are provided. When a user takes a photo of an object, an optical authentication system receives light reflected and/or emitted from the object. The system also receives a random key from an authentication server. The system converts the received light to plenoptic data and uploads it to the authentication server. In addition, the system generates an optical hash of the received light using the random key, converts the generated optical hash to a digital optical hash, and uploads the digital optical hash to the authentication server. When the authentication server receives the upload, it verifies whether the time of the upload is within a certain threshold time from the sending of the random key and whether the digital optical hash was generated from the same light as the plenoptic data.

A system includes first and second sets of communication devices. A processor coupled to the first set of communication devices produces a first encoded vector and transmits the first encoded vector to the second set of communication devices via a communication channel that applies a channel transformation to the first encoded vector during transmission. A processor coupled to the second set of communication devices receives the transformed signal, detects an effective channel thereof, and identifies left and right singular vectors of the effective channel. A precoding matrix is selected from a codebook of unitary matrices based on a message, and a second encoded vector is produced based on a second known vector, the precoding matrix, a complex conjugate of the left singular vectors, and the right singular vectors. The second encoded vector is sent to the first set of communication devices for identification of the message.

A digital communication method over an optical channel. Bob modulates a coherent optical signal with a random envelope phase φr, known to him and not to Alice, and transmits the modulated coherent optical signal (envelope) over the optical channel to Alice. Alice further modulates the envelope with a key phase φk, based on a secret key and a selected modulation scheme, to create a cipher envelope, and sends the cipher envelope towards Bob along the optical channel. Bob then demodulates a received version of the cipher envelope by removing the random envelope phase φr (known to Bob) and then measures the phase of the resulting demodulated coherent optical signal with the coherent detector to extract, to within a certain margin of error, the key phase φk, from which Alice's secret key can be decoded. Bob then uses the secret key for encrypting messages sent to Alice over any digital network.

A method for physical layer secure transmission against an arbitrary number of eavesdropping antennas includes: S1: communication between legitimate transmitter Alice and legitimate receiver Bob is confirmed; S2: Alice randomly generates a key bit b.sub.k with M.sub.S bits, maps the key bit b.sub.k into a key symbol K, and performs an XOR on the key bit b.sub.k and to-be-transmitted confidential information b to obtain an encrypted bits b.sub.s; S3: Bob transmits a pilot sequence to Alice, and Alice calculates a candidate precoding space W and transmits modulated symbol streams s=(s.sub.1, . . , s.sub.N) by using precoding W(e); S4: Bob measures received signal strength of each antenna, estimates the corresponding antenna vector e, inversely maps the vector e to obtain key symbols and key bits, and demodulates the received symbol streams in sequence at each activated antenna to obtain demodulated ciphertext bits; S5: Bob performs an XOR on observed key bits and the demodulated ciphertext bits to obtain the confidential information.

Systems and method are provided for using chaotic signals for low probability of detection (LPD) communications. Embodiments of the present disclosure provide systems and methods for synchronizing chaotic systems and then encoding information on a signal in a way that produces little or no signature (e.g., using a bit flipping technique or a chaos control encoding technique). Systems and methods in accordance with embodiments of the present disclosure can work with noise larger than the signal, so they are suitable for communication in noisy environments.

Provided are methods and systems for invalidating user security tokens. An example method may include providing, by one or more nodes in a cluster, a list of revoked security tokens. The method may include receiving, by the one or more nodes, an indication of invalidating a user security token associated with a user device. The indication may include a request from the user to invalidate the user security token. The method may further include, in response to the receiving, adding, by the one or more nodes, the user security token to the list of revoked security tokens. The user security token can be added to the list of revoked security tokens prior to the expiration time of the user security token. The method may further include replicating, by the one or more nodes, the list of revoked security tokens between further nodes of the cluster.

A method of encoding data includes identifying multiple complex number pairs of a data vector and generating a transformed data vector by applying a non-linear transformation to each complex number pair from the multiple complex number pairs. The non-linear transformation includes modifying a phase of a first complex number from each complex number pair. The phase modification is based on a value associated with a second complex number from each complex number pair. A signal representing the transformed data vector is sent to multiple transmitters for transmission to multiple receivers. A signal representing the non-linear transformation is sent to a compute device for transmission of the non-linear transformation to the multiple receivers prior to transmission of the signal representing the transformed data vector from the multiple transmitters to the multiple receivers, for recovery of the data vector at the multiple receivers.

Methods, systems, and devices for wireless communications are described. A user equipment (UE) and a serving base station may locally store secret information (e.g., side information, such as a secret key, a public key, etc.) that is used to protect physical (PHY) layer channel or signal transmissions. The UE and the serving base station may determine a next value of a pseudo random sequence that is a function of a current value of the pseudo random sequence and the secret information and may use the next value to determine a time-varying parameter. The UE and the serving base station may use this time-varying parameter to determine which tones, which symbols periods, or which sequence, is being used for a subsequent communication of a PHY layer channel or signal.

Provided are a light source for use in the field of quantum communication, and an encoding device using the light source. When the light source is applied to Z basis encoding, a high and stable extinction ratio can be provided, and two consecutive optical pulses having a stable phase relation can be provided for encoding under an X basis.

Provided are a light source for use in the field of quantum communication, and an encoding device using the light source. When the light source is applied to Z basis encoding, a high and stable extinction ratio can be provided, and two consecutive optical pulses having a stable phase relation can be provided for encoding under an X basis.