If your email account uses a BlackBerry Enterprise Server that supports this feature, you can digitally sign or encrypt messages to add another level of security to email and PIN messages that you send from your BlackBerry smartphone. Digital signatures are designed to help recipients verify the authenticity and integrity of messages that you send. When you digitally sign a message using your private key, recipients use your public key to verify that the message is from you and that the message hasn't been changed.
Encryption is designed to keep messages confidential. When you encrypt a message, your smartphone uses the recipient’s public key to encrypt the message. Recipients use their private key to decrypt the message.
To send an encrypted PIN message, you must have a PIN and an email address for the contact in your contact list. Your smartphone uses the email address in your contact list to locate a PGP key or certificate for the contact.