40-bit encryption

About: 40-bit encryption is a research topic. Over the lifetime, 5434 publications have been published within this topic receiving 149016 citations.

Quantum Homomorphic Encryption for Circuits of Low T-gate Complexity

Abstract: Fully homomorphic encryption is an encryption method with the property that any computation on the plaintext can be performed by a party having access to the ciphertext only. Here, we formally define and give schemes for quantum homomorphic encryption, which is the encryption of quantum information such that quantum computations can be performed given the ciphertext only. Our schemes allow for arbitrary Clifford group gates, but become inefficient for circuits with large complexity, measured in terms of the non-Clifford portion of the circuit (we use the “\(\pi /8\)” non-Clifford group gate, also known as the \(\mathsf{T}\)-gate).

Hidden Link Dynamic Key Manager for use in Computer Systems with Database Structure for Storage and Retrieval of Encrypted Data

Abstract: of Disclosure A computer system (20) with a security domain (22), at least one client business domain (26), and a plurality of client terminals (34) utilizes a hidden link dynamic key manager (24, 84) and a database structure including encrypted data entities (30C, 30D) and a security identification attribute (32) for storage of encrypted data. A method for encryption, storage, decryption, and retrieval of encrypted data operates on the computer system (20), which also includes an information database (62) and a key database (44). The key database (44) is isolated from the information database (62). The security domain (22) includes a system key manager (84) operable to generate system keys with system key common names and an encryption key manager (24) operable to generate encryption keys having encryption key identifications. The key managers (24, 84) operate on a key server (40), which is mirrored by a secondary key server (42). A general security manager (82) also operates on the key server (40) to control access to the security domain (22). The security information attribute (32) is stored with a persistent data entity (30A) that is associated with the other data entities (30C, 30D) by a database schema. The security information attribute (32) includes the encryption key identification (112) for the encryption key used to encrypt the data entities (30C, 30D). The encryption key identification is encrypted by the system key, and the system key common name hash value (114) is also stored in the security information attribute (32). The information data entities (30) are stored on the information database (62), but the encryption key identification (153), encryption key (154), system key common name hash value (156, 157), and system key common name (158) are stored in the key database (44) inside the security domain (22). The system key itself is stored on a Smart Card reader (56) inside the security domain.

Secure content objects

Abstract: A secure content object protects electronic documents from unauthorized use. The secure content object includes an encrypted electronic document, a multi-key encryption table having at least one multi-key component, an encrypted header and a user interface device. The encrypted document is encrypted using a document encryption key associated with a multi-key encryption method. The encrypted header includes an encryption marker formed by a random number followed by a derivable variation of the same random number. The user interface device enables a user to input a user authorization. The user authorization is combined with each of the multi-key components in the multi-key encryption key table and used to try to decrypt the encrypted header. If the encryption marker is successfully decrypted, the electronic document may be decrypted. Multiple electronic documents or a document and annotations may be protected by the secure content object.

Encryption-based selection system for steganography

Abstract: A data security system which produces a steganographic selection key by using an encryption key as both the key and as the data to be encrypted. First an encryption key is copied multiple times to form a data block which is then encrypted using the same key. The resulting ciphertext is then used as a selection key to select locations in a secondary data stream. These selected locations are then modified with the original data to be encoded. Restoration of the original data is accomplished by using the selection key to locate the modified areas of the data stream, extracting the data found there, and then decrypting the extracted data with the cyphertext.

A novel image encryption based on hash function with only two-round diffusion process

Abstract: In this paper, a novel algorithm for image encryption based on hash function is proposed. In our algorithm, a 512-bit long external secret key is used as the input value of the salsa20 hash function. First of all, the hash function is modified to generate a key stream which is more suitable for image encryption. Then the final encryption key stream is produced by correlating the key stream and plaintext resulting in both key sensitivity and plaintext sensitivity. This scheme can achieve high sensitivity, high complexity, and high security through only two rounds of diffusion process. In the first round of diffusion process, an original image is partitioned horizontally to an array which consists of 1,024 sections of size 8 × 8. In the second round, the same operation is applied vertically to the transpose of the obtained array. The main idea of the algorithm is to use the average of image data for encryption. To encrypt each section, the average of other sections is employed. The algorithm uses different averages when encrypting different input images (even with the same sequence based on hash function). This, in turn, will significantly increase the resistance of the cryptosystem against known/chosen-plaintext and differential attacks. It is demonstrated that the 2D correlation coefficients (CC), peak signal-to-noise ratio (PSNR), encryption quality (EQ), entropy, mean absolute error (MAE) and decryption quality can satisfy security and performance requirements (CC 204.8, entropy >7.9974 and MAE >79.35). The number of pixel change rate (NPCR) analysis has revealed that when only one pixel of the plain-image is modified, almost all of the cipher pixels will change (NPCR >99.6125 %) and the unified average changing intensity is high (UACI >33.458 %). Moreover, our proposed algorithm is very sensitive with respect to small changes (e.g., modification of only one bit) in the external secret key (NPCR >99.65 %, UACI >33.55 %). It is shown that this algorithm yields better security performance in comparison to the results obtained from other algorithms.