Patent application number | Description | Published |
20080256362 | Method and apparatus for digital signature authentication, and computer product - An apparatus for digital signature authentication includes a dividing unit that divides streaming data into plural pieces of partial data in a predetermined unit; a first creating unit that creates a hash value string including plural hash values corresponding to the pieces of partial data; a second creating unit that creates a first binary tree using the hash value string; and a third creating unit that creates a digital signature of a signer using a root value of the first binary tree. | 10-16-2008 |
20090013379 | METHODS AND APPARATUS FOR VERIFYING ELECTRONIC MAIL - A computer extracts the header information from an electronic mail, including an originality guarantee. The computer generates a header characterization for the header information subject to originality guarantee, and extracts message body information from the electronic mail and generates a body characterization for the message body information as well. The generated characterization set applies the header characterization and the body characterization, combined. The verification information is added to the generated characterization set for applying a signature, and characterization set is linked to electronic mail. | 01-08-2009 |
20090193256 | ELECTRONIC SIGNATURE METHOD, APPARATUS, AND RECORDING MEDIUM HAVING ELECTRONIC SIGNATURE PROGRAM RECORDED THEREON - A computer divides a target electronic document into a plurality of document segments. Then, the computer generates a signature (s, t) that includes a set of two values having a signature value s forming a signature on the electronic document and a deletion signature value t used for deletion, the signature value s which serves as a body of the signature being formed by a superposition of signature information on the individual document segments. Then, in a case where one of the plurality of document segments obtained by the division is to be extracted, the computer superimposes deletion information of a document segment to be deleted on the deletion signature value t to generate a new signature value t′, and produces an updated signature (s, t′). | 07-30-2009 |
20090207997 | ELLIPTIC CURVE CRYPTOSYSTEM APPARATUS, STORAGE MEDIUM STORING ELLIPTIC CURVE CRYPTOSYSTEM PROGRAM AND ELLIPTIC CURVE CRYPTOSYSTEM ARITHMETIC METHOD - A scalar multiplication can be performed on an elliptic curve cryptosystem at a high speed. P is set as an initial value of Q[0], and 2×P is set as an initial value of Q[1]. An elliptic curve doubling ECDBL of Q[d[i]] is performed, and an arithmetic result is stored in Q[2]. An elliptic curve addition ECADD of Q[0] and Q[1] is performed, and an arithmetic result is stored in Q[1]. Q[2−d[i]] is stored in Q[0]. Q[1+d[i]] is stored in Q[1]. The elliptic curve addition ECADD and the elliptic curve doubling ECDBL are concurrently performed in the respective processors. | 08-20-2009 |
20090210715 | Document verification apparatus, document verification method, and computer product - In verifying a digital document, an input of a digital document is received and the digital document is divided into arbitrary constituent parts. A normal random number or a pseudo random number is assigned to each of the constituent parts according to the order in which the constituent parts appear in the digital document. Thus, verification of the authenticity of a digital document is enabled even when an alteration, such as a change of the order of the partial documents or a copy thereof, has been made to the digital document. | 08-20-2009 |
20090265558 | DOCUMENT VERIFYING APPARATUS, DOCUMENT VERIFYING METHOD, AND COMPUTER PRODUCT - A computer-readable recording medium stores therein a document verifying program. The document verifying program causes a computer to execute receiving input of an electronic document; dividing the electronic document received into arbitrary components; calculating a hash value for each of the components; correlating, for each component, the hash value calculated for the component and a random number allocated to the component according to an appearance position of the component in the electronic document; creating for each component and based on the hash value and the random number correlated for the component at the correlating, a first digital signature and a second digital signature that are different from each other; and appending to each component, the first digital signature and the second digital signature created for the component at the creating. | 10-22-2009 |
20090290189 | Electronic document managing apparatus - An integrator acquires an electronic document and revised documents revised by different revisers (administrative department, accounting department) in parallel, and makes reference to the electronic document to judge whether each partial document is not disclosed in each revised document with respect to each sub-document in the electronic document. When each sub-document is not disclosed in at least one of the revised documents, whether each sub-document is to be disclosed is determined in regard to each sub-document based on a policy P that specifies disclosure/nondisclosure of each sub-document divided from the electronic document, and a revised document obtained by integrating the revised documents is created based on a determination result. | 11-26-2009 |
20100005306 | STORAGE MEDIA STORING ELECTRONIC DOCUMENT MANAGEMENT PROGRAM, ELECTRONIC DOCUMENT MANAGEMENT APPARATUS, AND METHOD TO MANAGE ELECTRONIC DOCUMENT - An electronic document management apparatus acquires an electronic document comprised of a plurality of components for each of which a first digital signature and a second digital signature are uniquely specified. The electronic document is linked to an aggregate digital signature which aggregates the first digital signatures. After that the apparatus accepts designation of a component to be “hiding prohibited” within the electronic document. Whether or not the component designated to be “hiding prohibited” is at that time in a state of “hiding allowed and deletion allowed” is judged. When the judgment reveals that the state is “hiding allowed and deletion allowed”, the second digital signature specified for the component designated to be “hiding prohibited” is deleted. Then the state of the component subject to be “hiding prohibited” is changed from “hiding allowed and deletion allowed” to “hiding prohibited and deletion allowed”. | 01-07-2010 |
20100169653 | APPARATUS, METHOD, AND PROGRAM FOR DIGITAL SIGNATURE - A digital signature method to generate a signature for an electronic document, the method including: initializing a signature t of each of the document segments of electronic document and twice raising the signature t to the power of a hash value of each of the document segments and digitally signing the raised signature to produce a signature s serving as the signature of the electronic document; and revising a document segment; wherein, in the revising, to delete a document segment, the signature t is raised twice to the power of the hash value of the document segment unless the document segment is sanitization prohibited, or the signature t is raised to the power of the hash value of the document if the document segment is sanitization prohibited, and the document segment is deleted; to sanitize a document segment, the document segment is replaced with the hash value thereof. | 07-01-2010 |
20100232601 | ELLIPTIC CURVE ARITHMETIC PROCESSING UNIT AND ELLIPTIC CURVE ARITHMETIC PROCESSING PROGRAM AND METHOD - An apparatus for executing cryptographic calculation on the basis of an elliptic point on an elliptic curve includes: a memory for storing a first value including a plurality of digits; and a processor for executing a process including: obtaining a second value representing a point on the elliptic curve; calculating output values by using a predetermined equation, each digit of the first value, and the second value; determining whether at least one of the second value and the output values indicates a point of infinity; terminating the calculation when at least one of the second value and the output values indicates the point at infinity; and completing calculation when both the second value and the output values do not indicate the point at infinity, so as to obtain a result of the cryptographic calculation. | 09-16-2010 |
20110072278 | DATA PROCESSING APPARATUS AND DIGITAL SIGNATURE METHOD - A data processing apparatus includes, an input unit to accept information on one or more deletion-target data blocks specified from a plurality of data blocks, a hash generating unit to calculate a hash value of each of the plurality of data blocks, an auxiliary data generating unit to calculate auxiliary data β=g | 03-24-2011 |
20110078458 | CONTENTS PROCESSING DEVICE AND CONTENTS PARTIAL INTEGRITY ASSURANCE METHOD - A contents processing device includes a management data storage unit to store an updater identifier and a private key, an accepting unit to accept a content which is divided into a plurality of blocks, an updating type indicating a type of an updating as to the content, an updated block to be updated of the content, and an updated position, an inserting unit to generate an updated content by inserting the updating block into the updated position of the content, a first hash value calculating unit to calculate a hash value as to the updated block, a signature unit to read out the updater identifier and the private key from the management data storage unit to generate a digital signature using the private key as to updating record information including the updater identifier, the updated position, the hash value as to the updated block, and the updating type. | 03-31-2011 |
20110194693 | CRYPTOGRAPHIC PROCESSING APPARATUS AND METHOD - A cryptographic processing apparatus that encrypts plaintext using a fixed-value common key that is shared with other cryptographic processing apparatus, includes an acquiring unit that acquires random information being used within the cryptographic processing apparatuses, an encrypting unit that encrypts encryption target data using key information and outputs encrypted data when the encryption target data and the key information is set, a transmitting unit that transmits, to the other cryptographic processing apparatus, the encrypted data; and a setting unit that sets the fixed-value common key as the key information and the random information as the encryption target data when the random information is acquired by the acquiring unit, and sets the encrypted data as the key information and at least one portion of the plaintext as the target data when the encrypted data is acquired. | 08-11-2011 |