54 results about "Known-plaintext attack" patented technology
Filter
Efficacy Topic
Property
Owner
Technical Advancement
Application Domain
Technology Topic
Technology Field Word
Patent Country/Region
Patent Type
Patent Status
Application Year
Inventor
The known-plaintext attack (KPA) is an attack model for cryptanalysis where the attacker has access to both the plaintext (called a crib), and its encrypted version (ciphertext). These can be used to reveal further secret information such as secret keys and code books. The term "crib" originated at Bletchley Park, the British World War II decryption operation.
The invention relates to an image encryption method and an image decryption method with visual security and data security based on compressed sensing. The image encryption method comprises the steps of: firstly, utilizing an SHA 256 hash function to obtain a 256-bit hash value of a plaintext image as an image secret key, and calculating initial numerical values of one-dimensional skew tent chaotic mapping and zigzag scrambling; carrying out sparse processing on the plaintext image, and carrying out zigzag scrambling on a coefficient matrix; and then utilizing the one-dimensional skew tent chaotic mapping to generate a measurement matrix, measuring and quantifying a scrambling matrix to obtain a compressed and encrypted image, and embedding the image into a carrier image with visual significance to obtain a final ciphertext image with visual significance. The image encryption method realizes the visual security and data security of the plaintext image, has large secret key space, is highly sensitive to plaintext, has higher capacity of resisting brute-force attack, chosen-plaintext attack and known-plaintext attack, does not need an additional storage space, and can transmit and store the ciphertext image quickly and effectively.
The present invention provides an encryption method for a video data, which comprises the following procedures: the macro block information of the video data is abstracted; a primary scrambling matrix is created; the macro block information is scrambled according to the primary scrambling matrix; the scrambling result of the primary scrambling matrix is divided into a plurality of areas, and a relative area scrambling rule for each area is determined; a secondary scrambling matrix for the entire video data is gained according to the collocation result by the coding information and the relative area scrambling rule of the macro block in each area; the scrambling result of the primary scrambling matrix is scrambled again according to the secondary scrambling matrix; a stream data is built and an encryption result is gained. The present invention solves the problem of the existing macro block scrambling algorithm that a partial encryption effect is inadequate, provides a better visual encryption effect, and the known plain textattack is ineffective. In conclusion, the present invention does not increase the stream, the speed is quick, the computing source occupation is low, the security is high, and the present invention is more suitable for the most real time application scene of the video encryption.
A Method and Apparatus for a Security System for Wireless Networks is described. The technique involves encryption and decryption at the Physical layer. It also develops a criterion for choosing the encryption / decryption methodology for a particular embodiment for communication systems typically using a Viterbi Decoder and describes how the difficult-to-invert property of the Viterbi Decoder can be utilized to provide security against known-plaintext attacks. Some candidate encryption / decryption methodologies satisfying the developed criterion are also discussed.
The embodiment of the invention discloses a streaming media video encryption method and device based on H.264. The encryption method includes the steps that context-based adaptive variable length coding and QTC encryption are synchronously performed on the QTC, and the processed QTC is obtained; the prediction mode and motion vectors are scrambled, and the scrambled prediction mode and the scrambled motion vectors are obtained; multiplexing is performed on the processed QTC, the scrambled prediction mode and the scrambled motion vectors, and encrypted video data streams are input. Through the encryption method and device, the intra-frame prediction mode scrambling method in the prior art is improved, and Friedman key guessing and known plaintext attach can be prevented; safety of motion content is enhanced; the method is easy to achieve, real-time application complexity of data encryption in real-time application can be reduced, and the code error robustness of transmission of encrypted code streams is improved.
A configuration method of an optical signal, an encryption device, and an encryptionsystem makes it possible for a legitimate communicating party to ensure information-theoretic security against a known plain textattack and to communicate long-distance. By adding a transmission information data sequence randomization device to the Yuen encrypted communications device according to the present information, which divides transmission information data into blocks, appends sequence numbers thereto, randomly switches the sequence of the blocks with a digitized signal of output of an electrical noise generator, and inputs same into a transmission data generator of a conventional Yuen encrypted optical transmitter, the relation between a known transmission information data sequence (plain text) and an optical signal which is outputted from the transmitter is randomized, allowing forcibly making even a circumstance wherein a known-plain textattack would be possible into a cipher-text-only attack, realizing information-theoretic security against a known-plain text attack.
The invention discloses a region-of-interest medical image chaoticencryption method based on an information entropy update key, and relates to the technical field of image information security, whichcan overcome the security defects that an existing medical image encryption technology is low in encryption efficiency and cannot resist attacks of known plaintexts and selected plaintexts. Accordingto the information entropy updating key-based region-of-interest medical image chaotic encryption and decryption method provided by the invention, the region-of-interest of the medical image is processed by utilizing wavelet transform, so that the frequency domain encryption of the image is realized. Meanwhile, the hyperchaotic system is used for scrambling and diffusing the region of interest ofthe medical image, so that the protection of the image in a spatial domain is realized. Besides, according to the information entropy key updating method designed by the invention, the key is not only related to the parameters of the chaoticsystem, but also related to the plaintext image, so that known plaintext attacks or selected plaintext attacks can be resisted.
The invention relates to a multi-diffusion image encryption and decryption method based on cellular neural network chaos, which relates to the technical field of image encryption and solves the problems that the existing image encryption method is insufficient in key space and insufficient in randomness and solves the safety defects that known plaintext attacks and selected plaintext attacks can not be effectively resisted. A chaos control table and a quantum exchange table are generated by a quantumcellular neural network, intra-block and inter-block scrambling for plaintext images is carried out, and the correlation between image pixels is removed through multiple chaoticdiffusion steps with positive and negative diffusion and dynamic diffusion included. A quantumcellular neural network hyperchaotic system has a higher key dimension, larger key space, stronger sensitivity and stronger ability to resist various safety attacks, and as a quantum chaoticsystem is a novel nano-scale device which mutually transmits information under Coulomb interaction between quantum dots and a quantum cellular automata, the quantum cellular neural network hyperchaotic system has the advantages ofultra-high integration, low power consumption, lead-free integration and the like.
The invention relates to the technical field of image information security and optical information processing, can effectively resist known-plaintextattack and chosen-plaintextattack, and solves the problem of being inconvenient in key management and transmission on an aspect of key generation so as to further guarantee security. The optical imageencryption method based on four-step generalized phase shifting and multi-step Fresnel transform comprises the following steps of: 1) a key generation part: two random phase masks which perform a main key function are independently generated by Tinkerbell chaotic systems controlled by different chaotic parameters; 2) an image encryption part: four holograms are used for obtaining an encrypted image; and 3) an image decryption part: after an input image is subjected to Fresnel inverse transform of which the distance is Z2, the input image is subjected to complex conjugation modulation by a second chaotic random phase mask and is subjected to the complex conjugation modulation by a first chaotic random phase mask, and then, the obtained input image is subjected to the Fresnel inverse transform of which the distance is Z to obtain a decrypted image. The method is mainly applied to the field of image information security.