Patent ID: 7788484

Claim:
A method for authenticating electronic mail using hierarchical identity-based cryptography, comprising: in a hierarchy associated with a domain name service, wherein a first domain resides above a second domain, for the second domain, generating a second public key and second private key pair, wherein the second public key is derived using the domain name service and the second private key is generated using a first private key associated with the first domain; for an email server within the second domain, generating a third private key based on the first private key of the first domain; for each of a plurality of users, generating a respective public key and private key pair, wherein a respective public key for a user is derived from an associated user name and a respective private key for a user is generated using the third private key; receiving an email message from a sender to a recipient, wherein the email message is signed using a corresponding private key of the sender; and authenticating the sender using a corresponding public key of the sender, wherein the public key of the sender is derived using the domain name service.