Hitachi, Ltd.

Renesas Electronics Corporation

Katsuyuki Okeya

Camille Vuillaume

Masayuki Yoshino

Hiroshi Yoshiura

Makoto Kayashima

Kunihiko Miyazaki

Toru Owada

Isao Echizen

Kousuke Anzai

Jun'ichi Taguchi

Tsuyoshi Takagi

Kazunori Nakano

Shinichiro Harano

Erik Dahmen

A modular multiplication processing apparatus is provided that can process modular multiplication of data exceeding a bit length which a coprocessor can readily process, by using the coprocessor based upon Montgomery multiplication In the modular multiplication processing apparatus, data to be subjected to modular multiplication is decomposed, and the decomposed data elements are transformed into a form suitable for Montgomery multiplication, respectively. Further, after respective data elements are transformed to have sizes that can be inputted into a coprocessor, Montgomery multiplication is repeatedly performed in the coprocessor. A remainder of Montgomery multiplication of an original bit length is restored from the obtained remainder.

Modular multiplication processing apparatus

A technique for efficient encryption for use with devices such as smartcards restricted in memory resource, including a calculation unit for reconstructing a large number of small primes, a sieving unit for checking the divisibility of an integer by small primes, a recoding unit for changing the representation of an integer, and a primality testing unit. The sieving unit eliminates 'bad' candidates by checking their divisibility by small primes reconstructed by the calculation unit. The primality of the remaining candidates is tested using the primality testing unit. The primality testing unit uses the recoding unit to change the representation of prime candidates. The primality testing unit performs a primality test using the representation after change.

Data processing system and data processing method

A system and method for authentication and digital signatures on memory-only supports, comprising a read-once memory unit storing secret arrays, whose contents are destroyed upon reading, a standard memory unit storing encrypted arrays, tree data authenticating the encrypted arrays to one single public key, and a certificate of the public key issued by a certificate authority. The memory support sends its public key and certificate to a verifier, receives a challenge which is signed by elements from secret arrays in the read-once memory. The verifier system checks the authenticity of the data revealed from the read-once memory by encrypting it and comparing the result to one of the encrypted arrays, and verifies that the encrypted array authenticates to the public key using tree data. Finally, the verifier checks the authenticity of the public key using the certificate.

System and method for digital signatures and authentication

A modular multiplication processing apparatus is provided that can process modular multiplication of data exceeding a bit length which a coprocessor can process, by using the coprocessor based upon Montgomery multiplication In the modular multiplication processing apparatus, data to be subjected to modular multiplication is decomposed, and the decomposed data elements are transformed into a form suitable for Montgomery multiplication, respectively. Further, after respective data elements are transformed to have sizes that can be inputted into a coprocessor, Montgomery multiplication is repeatedly performed in the coprocessor. A remainder of Montgomery multiplication of an original bit length is restored from the obtained remainder.

A decryption method of decrypting a plaintext m from a secret exponent d, a public key n, and a ciphertext c includes steps of converting the ciphertext c into a randomized ciphertext t, a step of converting the randomized ciphertext t into a randomized plaintext u, and steps of converting the randomized plaintext u into the plaintext m.

Computation method for modular exponentiation operation in decryption or signature generation

A contents control method for controlling a process on the receiving side which is applied to contents transmitted from the transmitting side to the receiving side, includes a step of adding, when a predetermined block of the transmitted contents is an area where control information for controlling the process substance on the receiving side which is applied to the contents is added, the control information to the block. The method also includes a step of receiving a process designation concerning the transmitted contents, and a step of applying, when user information stored in a receiving side apparatus which receives the transmitted contents, or information concerning the receiving side apparatus satisfies conditions corresponding to the received process designation in the control information added to the block of the contents, a process corresponding to the process designation to the received block.

Method and system for contents control

In scalar multiplication method in which a point on an elliptic curve is randomized, but yet scalar multiplication can be calculated by the computational cost as much as that without randomization, an operation is carried out upon a point randomized and a point not randomized in a scalar multiplication method to calculate a scalar-multiplied point from a scalar value and a point on an elliptic curve. The result of the operation is randomized while the computational cost becomes as much as that without randomization.

Elliptic scalar multiplication system

A cryptographic processing method in which dependence of cryptographic processing process and secret information on each other is cut off; and in which, when a scalar multiplied point is calculated from a scalar value and a point on an elliptic curve in an elliptic curve cryptosystem, a value of a bit of the scalar value is judged; and in which operations on the elliptic curve are executed a predetermined times and in a predetermined order without depending on the judged value of the bit.

Growing community of inventors

Yokohama, Japan

Katsuyuki Okeya