Digital Signature

About Digital Signature

Digital Signature uses Public Key cryptography, a technology used for e-mail, and other data encryption. A pair key consisting of two related keys are generated before sending data; one is called the "private" key, and the other is called the "public" key. The private key must be kept secretly by the message receiver (the one who generated the pair key). On the other hand, the public key can be sent to anybody, because it cannot decipher the message encrypted using the other public keys. The message encrypted using the public key can only be decrypted by the related private key. Thus the sender can use the public key to encrypt message, and nobody except for the private key holder can decrypt the data. Digital Signature works in the opposite way. Now the private key holder sends non-encrypted data along with the message encrypted with the private key. Anybody is able to read the data, and if the attached encrypted data can be decrypted by the public key, the data is proved that it was sent by the private key holder. The message cannot be decrypted if it is altered by an unauthorized, so it also secures the data from couterfeiting.

PostgreSQL CE office attaches an unique encrypted message using the private key, and send the certificates to the certified qualifiers. The certificate requires the digital ID certificate, equivalent to the public key, for a verification. PostgreSQL CE office sends the public key along with the certificate to the qualifier, and it is also open to download at our web site. Therefore, any third party can also verify that the qualifier's certificate is valid and issued by PostgreSQL CE office.

1. PostgreSQL CE office attaches a Digital Signature using the private key.
2. PostgreSQL CE office sends a certificate and the Digital ID certificate via e-mail.
   
3. A certified qualifier can verify the signature using the Digital ID certificate.
4. A certified qualifier sends his certificate to a third party if requested.
5. A third party downloads the Digital ID certificate from PostgreSQL CE office.
6. A third party can verify the signature using the Digital ID certificate.

How to import the Digital ID Certificate

The digital ID certificate, sent via the e-mail to qualifiers or downloaded from this site, are equivalent to the public key. Here are the steps to import the digital ID certificate into Acrobat 6.0 or Adobe Reader 6.0.

1. By double-clicking the digital ID certificate (extension .fdf), Acrobat or Adobe Reader will start, and [Data Exchange File - Import Contact] dialog box will be displayed.
   

2. In the [Data Exchange File - Import Contact] dialog box, click [Set Contact Trust...], and open the [Import Contact Settings] dialog box.

3. Check the [Trust signatures created with this certificate] box, and click [Import].

4. In the [Import Complete] dialog box, click [OK].
   

Comfirming the Digital Signature

After importing the digital ID certificate, a verification is automatically done whenever the certificate is opened with Acrobat 6.0 or Adobe Reader 6.0. You can check if the certificate is successfully verified by looking at the left bottom part of the displayed certificate. The certificate will show the image as below.

• Before importing the digital ID certificate
  

• After importing the digital ID certificate
  

Navigation Tab also shows the following difference before/after importation.

• Before importing the digital ID certificate
  

• After importing the digital ID certificate
  

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