The program uses industrial standard Public-Private Keys to digitally sign documents to prevent illegal modification or piracy. Essentially, you first create a key pair: a Public Key and a Private Key. You keep the Private Key safely while sending the Public Keys to others.

You may use a digital signature for multiple purposes.

• Sign a document using a Private Key: Since only you own the Private key (used to sign the document), if your public key (distributed to the public) can decrypt the file successfully, people can be sure the file is signed by your Private key; in other words, by you. Once signed with the private key, any modification of the document will break the seal.

• Encrypt a document using a Public Key: You can also send a private document to a friend (encrypting the document with your friend’s public key) so that no one else can read it.

Digital signatures can be visible or invisible. Visible signatures appear in documents and both on the Signatures panel and the Sign/Certify panel. Invisible signatures appear only on the Signatures panel and the Sign/Certify panel.

To change the appearance of signatures and specify validation and signature creating choices, select File > Options > Signatures using the signature preferences panel.

Digital signatures can be time stamped for increased security.