Identity-Based Encryption (IBE) is a type of public key encryption in which the public key of a user is some unique information about the identity of that user, such as his/her email address. A trusted third-party server, called the private-key generator, uses a cryptographic algorithm to calculate the corresponding private key from the public key. In this way, users can generate their own private keys directly from the server as needed, without the need to distribute their public keys.