Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A method and an apparatus capable of realizing at a high speed an elliptic curve cryptography in a finite field of characteristic 2, in which the elliptic curve is given by y2+xy=x3+ax2+b (b?0) and an elliptic curve cryptography method which can protect private key information against leaking from deviation information of processing time to thereby defend a cipher text against a timing attack and a differential power analysis attack are provided. To this end, an arithmetic process for executing scalar multiplication arithmetic d(x, y) a constant number of times per bit of the private key d is adopted. Further, for the scalar multiplication d(x, y), a random number k is generated upon transformation of the affine coordinates (x, y) to the projective coordinates for thereby effectuating the transformation (x, y)?[kx, ky, k] or alternatively (x, y)?[k2x, k3y, k]. Thus, object for the arithmetic is varied by the random number (k).

Abstract: In encryption techniques using an elliptic curve, in order to use a homogeneous coordinate system [X, Y, Z], a high speed [X1, Y1, Z1, (Z1)2, (Z1)3] for the addition and a high speed [X1, Y1, Z1] for the doubling the following schemes are provided: (1) Addition is executed by [X3, Y3, Z3]=[X1, Y1, Z1, (Z1)2, (Z1)3]+[X2, Y2, Z2]. (2) Doubling is executed by a conventional [X3, Y3, Z3]=2[X1, Y1, Z1] and an addition operation is executed by [X3, Y3, Z3]=[X1, Y1, Z1, (Z1)2, (Z1)3]+[X2, Y2, Z2]. It is also required to speed up the multiplication modulo operation.

Abstract: Hash values, keys and cipher text which have a high degree of data scrambling are generated rapidly. When a message is sent, divisional data of the message are input, and injection extension processing is performed so that the data length of output data is longer than the data length of input data. Further, hash values are generated by a hash function containing multiplication processing, cyclic shift processing, etc.

Abstract: A digital signature generating/verifying method using a public key encryption scheme which ensures high security, reduction in length of the digital signature and independency of the length of the digital signature on that the order of a base point. In generating a digital signature, a first hash value (e) satisfying a condition that e=H(M) is determined for a given message (M) by using a hash function (H), a numerical value (x) is obtained from translation of a random number, a hash value (r) satisfying a condition that r=h(x) is determined by using a hash function (h) whose output value is shorter than that of the first hash function (H), and the digital signature is generated by using the hash values (e) and (r) as determined.

Abstract: The present invention provides a symmetric-key cryptographic technique capable of realizing both high-speed cryptographic processing having a high degree of parallelism, and alteration detection.

Abstract: The present invention provides a symmetric-key cryptographic technique capable of realizing both high-speed cryptographic processing having a high degree of parallelism, and alteration detection.

Abstract: A key recovery method and system capable of key recovery without informing a third party of one's own secret key are disclosed. For realization of the method, a transmitting information processor generates a data value satisfying a relational expression by which if one of data obtained by converting a first public key and used as a cipher text generating parameter and data obtained by converting at least one second public key is decided, the other can be determined. The transmitting processor transmits a cipher text applied with the generated data value to a first receiving information processor which has a secret key paired with the first public key and at least one second receiving information processor which has a secret key paired with the second public key.

Abstract: A method and apparatus for generating a highly secured hash value without deteriorating the processing speed is provided. A hash function such that when a message M is given, the message M is compressed so as to have a certain kind of characteristics of cipher is realized. In a step, (1) one to one expanding process so that divided data of the message is inputted and longer data is outputted is executed, and (2) a plurality of cyclic shifting processes in which the number of shifting is different are executed. Consequently, the hash function can be calculated at higher speed than a conventional method of simple repetitive compression of divided data of a message.

Abstract: Hash values, keys and cipher text which have a high degree of data scrambling are generated rapidly. When a message is sent, divisional data of the message are input, and injection extension processing is performed so that the data length of output data is longer than the data length of input data. Further, hash values are generated by a hash function containing multiplication processing, cyclic shift processing, etc.