Hitachi, Ltd.

Tokyo, Japan

Soichi Furuya

Kazuo Takaragi

Dai Watanabe

Masashi Takahashi

Kunihiko Miyazaki

Hisayoshi Sato

Hiroyuki Kurumatani

Hiroo Okamoto

Takaharu Noguchi

Manabu Sasamoto

Hiroyuki Koreeda

Shigeru Hirahata

Makoto Aikawa

Michael Roe

A symmetric-key cryptographic technique capable of realizing both high-speed cryptographic processing having a high degree of parallelism, and alteration detection. The invention includes dividing plaintext composed of redundancy data and a message to generate plaintext blocks each having a predetermined length; generating a random number sequence based on a secret key, generating a random number block corresponding to one of the plaintext blocks from the random number sequence, outputting a feedback value obtained as a result of operation on the one plaintext block and the random number block, the feedback value being fed back for using the operation on another plaintext block, and performing an encryption operation using the one plaintext block, random number block, and feedback value.

Method and apparatus for symmetric-key decryption

In a buffer and a state included in a pseudorandom number generating apparatus, the state has the configuration of assuming that the unit length of data processing is n, the state has a size of 3&#xd7;n bits, and the buffer has a capacity of 32&#xd7;n bits, and according to clock control, a state transformation section (state transformation function) for conducting a state alteration from time t to time t+1 uses a nonlinear function F (having an n-bit input and an n-bit output) twice, or two different nonlinear functions F and G respectively once. The state transformation section has such a configuration that a nonlinear function such as a round function of a block cipher sufficiently evaluated as to the cryptographic security and implementation.

Pseudorandom number generating apparatus or encryption or decryption apparatus using the same

A symmetric-key cryptographic technique capable of realizing both high-speed cryptographic processing having a high degree of parallelism, and alteration detection. The invention includes dividing plaintext composed of redundancy data and a message to generate plaintext blocks each having a predetermined length, generating a random number sequence based on a secret key, generating a random number block corresponding to one of the plaintext blocks from the random number sequence, outputting a feedback value obtained as a result of operation on the one plaintext block and the random number block, the feedback value being fed back for using in the operation on another plaintext block, and performing an encryption operation using the one plaintext block, random number block, and feedback value.

An encryption system comprises a pseudo-random number generator (KS) for generating a long pseudo-random sequence (S) from a shorter encryption key (K) and, if necessary, a nonce value (N), and a mixing function (MX) for combining the sequence with a plaintext message (P) on a block-by-block basis, where successive blocks (S(i)) of 128 bits of the sequence are combined with successive 64-bit blocks of plaintext (P(i)) to produce successive 64-bit blocks of ciphertext. The blockwise use of a long pseudo-random sequence preserves the advantages of a block cipher in terms of data confidentiality and data integrity, as well as benefiting from the speed advantages of a stream cipher.

Cryptographic apparatus and method

A symmetric-key cryptographic technique capable of realizing both high-speed cryptographic processing having a high degree of parallelism, and alteration detection. The invention includes dividing plaintext composed of redundancy data and a message to generate plaintext blocks each having a predetermined length, generating a random number sequence based on a secret key, generating a random number block corresponding to one of the plaintext blocks from the random number sequence, outputting a feedback value obtained as a result of operation on the one plaintext blocks and the random number block, the feedback value being fed back for using in the operation on another plaintext blocks, and performing an encryption operation using the one plaintext blocks, random number block, and feedback value.

Method and apparatus for symmetric-key encryption

Encrypting/decrypting conversion method and apparatus capable of controlling dynamically cyclic shift independent of data to undergo encrypting/decrypting conversion includes two or more different fixed circulating shift processing means for shifting cyclically the data by a fixed bit number leftward or rightward, a cyclic shift processing selecting means for selecting fixed cyclic shift processing means. The selecting sequence determined by the cyclic shift processing means is determined on the basis of data for determining the shift number selecting sequence.

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Fujisawa, Japan

Soichi Furuya