Patent ID: 8296559

Claim:
A computer-implemented method comprising: generating, by a mail client of a sender client device, a public and private key pair; generating, by the mail client, a self-signed certificate of a sender that includes the public key of the public and private key pair, wherein the sender acts as its own certificate of authenticity issuer for the self-signed certificate; forming, by the mail client, an introduction message comprising the self-signed certificate of the sender and an authenticated attribute, the introduction message addressed to a recipient, wherein the authenticated attribute is out of band proof comprising a password-based encryption (PBE) of a hash of the self-signed certificate that is based on a user-selected password for the introduction message; and sending, by the mail client, the introduction message to the recipient; wherein when the introduction message is received at a mail client of the recipient, the introduction message triggers the mail client of the recipient to provide a user interface that queries the recipient to confirm the user-selected password for the introduction message and to accept the self-signed certificate upon confirmation of the user-selected password.