OpenOffice.org OpenOffice - 3.3 Guide de démarrage rapide télécharger pdf (Page 287)

Figure 281: Sending a document as an email message

7) Type a subject for your email and click Send documents. OOo sends the e-

mails.

Digital signing of documents

To sign a document digitally, you need a personal key, also known as a certificate.

A personal key is stored on your computer as a combination of a private key, which

must be kept secret, and a public key, which you add to your documents when you

sign them. You can get a certificate from a certification authority, which may be a

private company or a governmental institution.

When you apply a digital signature to a document, a kind of checksum is computed

from the document’s content plus your personal key. The checksum and your public

key are stored together with the document.

When someone later opens the document on any computer with a recent version of

OpenOffice.org, the program will compute the checksum again and compare it with

the stored checksum. If both are the same, the program will signal that you see the

original, unchanged document. In addition, the program can show you the public key

information from the certificate. You can compare the public key with the public key

that is published on the web site of the certificate authority. Whenever someone

changes something in the document, this change breaks the digital signature.

On Windows operating systems, the Windows features of validating a signature are

used. On Solaris and Linux systems, files that are supplied by Thunderbird, Mozilla or

Firefox are used. For a more detailed description of how to get and manage a

certificate, and signature validation, see “About Digital Signatures” in the OOo Help.

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OpenOffice.org OpenOffice - 3.3 Guide de démarrage rapide Page 287