Abstract: Certification/verification of authenticity and integrity of a digital document can be achieved, using meta information and content information and third-party certification thereof is achieved.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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 ?=gH1(mod N) of a signer based on predetermined values g and N and a product H1 of the hash values of one or more deletion-target data blocks, a digital signature generating unit to calculate intermediate data ?=gH2(mod N) based on the predetermined values g and N and a product H2 of the hash values of one or more remaining data blocks to generate a digital signature for a combination of the intermediate data ? and position data of one or more deletion-target data blocks with a signing key of a modifier.

Abstract: Disclosed is a digital document management program capable of achieving a third-party certification of document information with reduced amount of meta data. At the registration time of new document information, the digital document management program manages a digital signature created in association with document information. At the correction time of the document information, the program acquires partial identification information related to a corrected part of the document information before correction, creates a digital signature to be appended to the corrected document information, and manages the digital signature and partial identification information related to the corrected part of the document information in association with the corrected document information.

Abstract: 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.

Abstract: A method for generating a digital signature with respect to an electronic document, the method including: inputting a target electronic document and a corresponding digital signature ?; dividing the target electronic document into a plurality of partial documents mi; and when a revision of the partial documents is to be performed, in a case where deletion of the one partial document is to be performed, when sanitization is not prohibited, exponentiating the digital signature ? twice with a hash value Gi, when sanitization is prohibited, exponentiating ? with the Gi; in a case where sanitization is to be performed, replacing a partial document by Gi; in a case where deletion is to be prohibited, exponentiating ? with a hash value Hi; in a case where the sanitization is to be prohibited, exponentiating ? with Gi; and updating ?.

Abstract: 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.

Abstract: 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”.

Abstract: An elliptic curve cryptosystem apparatus performing an elliptic curve cryptosystem process has a coordinate transforming unit for transforming coordinates (X:Y:Z) on a point P on an elliptic curve over a finite field GF(p^m) to coordinates (r1×(X?s1):r2×(Y?s2):r3×(Z?s3)) (where, p is a prime number, m is an integer not less than 1, r1, r2 and r3 are integers not less than 1 and not larger than (p?1), s1, s2 and s3 are integer not less than 0 and not larger than (p?1), and a code “^” represents power), and a scalar multiplication operating unit for performing scalar multiplication on the point on the elliptic curve transformed by the coordinate transforming unit, wherein at least one of the parameters s1, s2 and s3 has a value other than 0. The apparatus can perform the scalar multiplication in the elliptic curve cryptosystem, with resistance to side channel attacks.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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?).

Abstract: An encryption device performs elliptic curve encryption using a secret key. The encryption device includes an operation unit for performing scalar multiplication of a point on an elliptic curve a storage unit having a plurality of data storing areas and a determiner unit for determining, in accordance with a bit sequence of a given value (d) and with a random value (RNG), an address of one of the plurality of data storage areas that is to be coupled to the operation means for each scalar multiplication.

Abstract: 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.