Microsoft Fax protects valuable and confidential documents through encryption and digital signatures. An encrypted fax can be read only by the intended recipient, who has a set of keys to unlock it or a password. A digitally signed fax allows a recipient to verify that the purported sender of the fax is the actual sender. You can use a digital signature on its own or add a digital signature to a fax protected with password or key encryption.
Password and key encryption.
You can encrypt a fax or binary file by using either a simple password or a public or private key pair. Password encryption, which is the simplest security method, scrambles a fax based on a specific password. The fax recipients can only unscramble the fax if they know the password. Password encryption does not require the exchange of public keys with your recipients, but you will need to tell them the password that you used to secure the fax.
When you use key encryption, Microsoft Fax assigns you two security keys, a private key and a public key. You can exchange public keys with anyone you choose. When you send a key-encrypted message, Microsoft Fax uses the recipient's public key and your private key to encrypt the message. When the message is received, Microsoft Fax uses your public key and the recipient's private key to decrypt it. Using your own private key ensures that the message could have been sent only by you. Using the recipient's public key ensures that only the recipient can unlock the message.You can store and maintain the public keys you receive from other users in your Microsoft Exchange Personal Address Book.
Note
Microsoft Fax applies security only to those faxes that have been sent as editable files. Rendered faxes cannot be secured.
Digital signatures.
Using a digital signature to secure a fax is similar to notarizing a document; it verifies for the recipient that the person who signed the document is the person who sent it. Digital signatures prevent anyone but the sender from modifying the document while it is being sent.
Digital signatures can only be used with binary file documents, that is, those that have been attached to mail messages (not rendered). Before you can use digital signatures, you must establish security and exchange public keys with a recipient as described later in this section.