# About Digital Certificate

Digital Certificate is one of the signature modules you can use in DocuWorks.

## About Digital Certificate

Digital Certificate provides the function to digitally sign a DocuWorks document and the function of encryption security, based on the Public Key Infrastructure (hereafter called the PKI). In order to use Digital Certificate, you must obtain a valid public key certificate (hereafter called a certificate) from a Certification Authority (CA).

## About signatures with the use of Digital Certificate

A digital signature generally means a signature made electronically, but in this topic refers to signing with the use of a private key possessed only by a specific user on DocuWorks documents, based on the public key cryptographic technology. Upon accepting the signed document, you can extract its signer's public key from the certificate and verify the signature. You can confirm that the DocuWorks document has not been changed since it was signed and that the signer himself / herself owns the private key.

## Difference from DocuWorks Electronic Signature

DocuWorks Electronic Signature is designed to be used within a small number of people who know one another. Using it on an external server or under a service contract with the third-party organization is not assumed.
On the other hand, Digital Certificate is a module based on the standard specifications which DocuWorks and other PKI applications can use in common, and is largely intended for use on the Internet among a large number of people.
Proof Information of Electronic Signature
To use the DocuWorks Electronic Signature function, the users create DocuWorks internal information called "Proof Information" for respective users, and they exchange the information beforehand. "Proof Information" must be exchanged in a trustworthy manner, for example, by hand. When DocuWorks Electronic Signature is to be used in a large group, it is difficult to pass and receive the "Proof Information" among users who don't know one another.
Digital Certificate
The Digital Certificate module uses digital information called "certificate". The "certificate" is in a format which is common to all PKI applications. Once the certificates issued to respective users are exchanged, any PKI applications can be used.
To input/output a "certificate" to/from the PC or to search for a "certificate", use the facility provided by the OS or a PKI application other than DocuWorks.
When you have acquired a "certificate", you can use various PKI applications including S/MIME mail, Web services access, digital signing, IC cards, and business-application software.

When using the Digital Certificate module among a large group of people, you may select a setting where a user is recognized as acceptable if the user has registered with a Certification Authority (CA) that issues "certificates."
In the cases of contacting a user whom you are not familiar with, you can use a setting where you trust a person if the person has been issued a "certificate" from a trusted Certification Authority.
In order to use the Digital Certificate module, you must have a "certificate" issued separately from DocuWorks. To have a certificate issued, you usually set up a certificate issuing server or sign a contract with a certificate issuing service.