Apparatus and method for authenticating digital signatures and computer-readable recording medium thereof
AssigneeFujitsu Limited
InventorSyuichi Satake
Life of this patent
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Abstract
In an apparatus for authenticating a digital signature, a signature generating part encrypts a digital document by using a private key defined by a signer and digest information for checking whether the digital document has been tampered with, and generates a digital signature. A signature synthesizing part creates image information by synthesizing the digital signature and a predetermined mark. And an image embedding part embeds the image information created by said signature synthesizing part into an indicated position in the digital document.
Claims12
An apparatus for authenticating a digital signature, comprising:
- a signature generating part encrypting a digital document by using a private key defined by a signer and digest information for checking whether the digital document has been tampered with, and generating a digital signature;
- a signature synthesizing part creating image information by synthesizing the digital signature and a predetermined mark, which enables a receiver to visually recognize a mark of the signer, wherein the digital signature is embedded in a predetermined color other than a color used for the mark of the signer in the predetermined mark;
- and
- an image embedding part embedding the image information created by said signature synthesizing part into an indicated position in the digital document.
An apparatus for authenticating a digital signature, comprising:
- a signature extracting part extracting the digital signature from image information embedded into a digital document, said image information capable of showing a predetermined mark, which enables a receiver to visually recognize a mark of a signer of the digital signature, wherein the digital signature is extracted from a predetermined color other than a color used for the mark of the signer in the predetermined mark;
- a digest obtaining part decrypting the digital signature by a public key opened by a signer and obtaining first digest information for checking whether the digital document has been tampered with;
- and
- an authenticating part determining whether second digest information regenerated based on the digital document identically corresponds to the first digest information obtained by said digest obtaining part and authenticating the digital signature based on a result of the determination.
A method for authenticating a digital signature, comprising
- (a) encrypting a digital document by using a private key defined by a signer and digest information for checking whether the digital document has been tampered with, and generating a digital signature;
- (b) creating image information by synthesizing the digital signature and a predetermined mark, which enables a receiver to visually recognize a mark of the signer, wherein the digital signature is embedded in a predetermined color other than a color used for the mark of the signer in the predetermined mark;
- and
- (c) embedding the image information created in said step (b) into an indicated position in the digital document.
A method for authenticating a digital signature, comprising
- (a) extracting the digital signature from image information embedded into a digital document, said image information showing a predetermined mark, which enables a receiver to visually recognize a mark of a signer of the digital signature, wherein the digital signature is extracted from a predetermined color other than a color used for the mark of the signer in the predetermined mark;
- (b) decrypting the digital signature by a public key opened by a signer and obtaining first digest information for checking whether the digital document has been tampered with;
- and
- (c) determining whether second digest information regenerated based on the digital document identically corresponds to the first digest information and authenticating the digital signature based on a result of the determination.
A computer-readable recording medium having a program recorded therein for causing a computer to authenticate a digital signature, said program comprising the codes of:
- (a) encrypting a digital document by using a private key defined by a signer and digest information for checking whether the digital document has been tampered with, and generating a digital signature;
- (b) creating image information by synthesizing the digital signature and a predetermined mark, which enables a receiver to visually recognize a mark of the signer, wherein the digital signature is embedded in a predetermined color other than a color used for the mark of the signer in the predetermined mark;
- and
- (c) embedding the image information into an indicated position in the digital document.
A computer-readable recording medium having a program recorded therein for causing a computer to authenticate a digital signature, said program comprising the codes of:
- (a) extracting the digital signature from image information embedded into a digital document, said image information showing a predetermined mark, which enables a receiver to visually recognize a mark of a signer of the digital signature, wherein the digital signature is extracted from a predetermined color other than a color used for the mark of the signer in the predetermined mark;
- (b) decrypting the digital signature by a public key opened by a signer and obtaining first digest information for checking whether the digital document has been tampered with;
- and
- (c) determining whether second digest information regenerated based on the digital document identically corresponds to the first digest information and authenticating the digital signature based on a result of the determination.
Dependencies are inferred from the claim text.