Showing papers on "40-bit encryption published in 1993"

Description of a New Variable-Length Key, 64-bit Block Cipher (Blowfish)

Abstract: Blowfish, a new secret-key block cipher, is proposed. It is a Feistel network, iterating a simple encryption function 16 times. The block size is 64 bits, and the key can be any length up to 448 bits. Although there is a complex initialization phase required before any encryption can take place, the actual encryption of data is very efficient on large microprocessors.

SAFER K-64: A Byte-Oriented Block-Ciphering Algorithm

Abstract: A new non-proprietary secret-key block-enciphering algorithm, SAFER K-64 (for Secure And Fast Encryption Routine with a Key of length 64 bits) is described. The blocklength is 64 bits (8 bytes) and only byte operations are used in the processes of encryption and decryption. New cryptographic features in SAFER K-64 include the use of an unorthodox linear transform, called the Pseudo-Hadamard Transform, to achieve the desired “diffusion” of small changes in the plaintext or the key over the resulting ciphertext and the use of additive key biases to eliminate the possibility of “weak keys”. The design principles of K-64 are explained and a program is given, together with examples, to define the encryption algorithm precisely.

Encryption and authentication method and circuit for synchronous smart card

Abstract: Encryption circuits and methods, in particular for smart cards, are disclosed. Smart cards without microprocessors may be authenticated very simply by using encryption with a secret card data table on which recursive cycles are executed. During each cycle, a word is read out of the table, said word being at an address that is at least partially defined by the word read out in the previous cycle. The new address preferably consists of several bits from the previous word and a bit from internal card data, external data supplied by a card reader, or a register containing a partial encryption result.

A software-optimized encryption algorithm

Abstract: We describe a fast, software-oriented, encryption algorithm. Computational cost on a 32-bit processor is about 5 elementary machine instructions per byte of text. The cipher is a pseudorandom function; under control of a key (first pre-processed into an internal table) it stretches a short index into a much longer pseudorandom string. This string can be used as a one-time pad.

Novel image encryption technique and its application in progressive transmission

Abstract: A novel image encryption technique is proposed. The encrypted image is obtained by randomly changing the phase spectra of the original image. Therefore, the resulting image is unrecognized and the image encryption is achieved. The phase spectra of the original image are added with the binary phase spectra of a pseudo-noise. This type of image encryption is similar to the private-key cryptographic system. The attack study for the proposed image encryption scheme is also conducted. It is shown that the possibility of a successful attack for a 512 × 512 encrypted image is, at most, 1.25 × 10 -11 which requires 84 years by the state-of-the-art technology. The application of this type of encryption for the progressive transmission is also conducted. It is found that any part of the encrypted image can be used to reconstruct a meaningful original image. In addition, the encrypted image is insensitive to the presence of data loss. Therefore, in avoiding the network congestion it is suitable for the multimedia communications.

Joint encryption and message-efficient secure computation

Abstract: This paper connects two areas of recent cryptographic research: secure distributed computation, and group-oriented cryptography. We construct a probabilistic public-key encryption scheme with the following properties: - It is easy to encrypt using the public keys of any subset of parties, such that it is hard to decrypt without the cooperation of every party in the subset. - It is easy for any private key holder to give a "witness" of its contribution to the decryption (e.g., for parallel decryption). - It is "blindable": From an encrypted bit it is easy for anyone to compute a uniformly random encryption of the same bit. - It is "xor-homomorpbic": From two encrypted bits it is easy for anyone to compute an encryption of their xor. - It is "compact": The size of an encryption does not depend on the number of participants.Using this joint encryption scheme as a tool, we show how to reduce the message complexity of secure computation versus a passive adversary (gossiping faults).

A Software-Optimised Encryption Algorithm

Abstract: We describe a fast, software-oriented, encryption algorithm. Computational cost on a 32-bit processor is about 5 elementary machine instructions per byte of text. The cipher is a pseudorandom function; under control of a key (first pre-processed into an internal table) it stretches a short index into a much longer pseudorandom string. This string can be used as a one-time pad.

Encryption communication system

Abstract: An encryption communication system including: a communication center having at least a key information generating unit for generating key generating information used for encryption communication; and a plurality of user computers, each interconnected by a plurality of paths through the communication center, and each having at least an encryption key generating unit and an encryption processing unit. The communication center generates the key generating information Z based on predetermined modulo arithmetic formula. The user computer sends a password PW to the communication center, receives the key generating information therefrom, and generates an encryption key K used between the user computer and another party's computer based on predetermined modulo arithmetic formula. Further, the communication center provides a plurality of modulus numbers to share prime numbers assigned to at least two paths between the user computer and the other party's computer, and between the user computer and another party's computer, so that is possible to reduce the number of prime numbers.

Copying machine with encryption function

Abstract: Information is read from a medium such as paper in which information is written. The read information is enciphered. When encryption processing is performed, an encryption key is used. As the encryption key, an encryption key generated for each encryption is used, or an encryption key already generated is used again. The enciphered information is written into another medium such as paper. When decryption processing is performed, information is read from the medium in which the enciphered information is written. The read information is deciphered using as a decryption key the same key as the encryption key used when the encryption processing is performed. The deciphered information is written into another medium such as paper.

Synchronous smart card authentication and encryption circuit and method

Abstract: Encryption circuits and methods, in particular for smart cards, are disclosed Smart cards without microprocessors may be authenticated very simply by using encryption with a secret card data table on which recursive cycles are executed During each cycle, a word is read out of the table, said word being at an address that is at least partially defined by the word read out in the previous cycle The new address preferably consists of several bits from the previous word and a bit from internal card data, external data supplied by a card reader, or a register containing a partial encryption result

Devices for implementing public key cryptography and digital signatures

Abstract: The present invention provides a public key cryptosystem which comprises an encryption device, said device having means for encrypting information including a feed-back loop which evaluates a one-way or a one-way trap door function incorporating modular exponentiation with a small positive exponent and thereby processes successively the blocks into which the information has been divided, to encrypt the information; and a compatible decryption device. The encryption and decryption devices of the present invention provide an outstandingly high rate of encryption and decryption without impairing the level of security associated with public key cryptosystems.

A successful attack against the DES

Abstract: It is shown that the Data Encryption Standard (DES) function is divided into 68 subfunctions, and therefore the exhaustive key search attack could be done by a pipelining method. A chip is designed whose purpose is to attack the DES and a searching machine is detailed based on it. It is shown that the DES could be broken, easily and cheaply, by this machine.

Application of the isomorphic emphasis to spectrum scrambling encryption over analog speech channels

Abstract: In mobile communication, there is the danger that the content of communication may be intercepted. The encryption which protects confidentiality is studied from various approaches. The existing method, which merely adds an encryption function, increases the effective modulation index above the level without encryption and brings on a spread of radio frequency bandwidth. It has been shown that the effective modulation index can be maintained, when isomorphic emphasis applies to spectrum inversion encryption. It is established that isomorphic emphasis maintains this feature, even if it applies to an arbitrary spectrum scramble pattern. This circuitry configuration is the most economical when introduced into PM transmission.