HIBE: Hierarchical Identity-Based Encryption

Cryptosystems fundamentally deal with the issue of securing data communication. Public key infrastructure (PKI) model requires an authenticated public key for encryption that has to be obtained prior to initiating communication. The identity-based encryption (IBE) essentially removes the public key distribution by using an arbitrary string, e.g., an email address or a phone number, as the public key. A private key generator (PKG) delegates private keys to corresponding users for decryption. In trivial identity-based encryption schemes, a single private key generator for all the users makes key generation computationally inefficient. The hierarchical identity-based encryption (HIBE) eliminates this bottleneck of verifying the proofs of identity, generating private keys and establishing secure paths to transfer these keys. In HIBE, a root PKG with a secret master key distributes the workload by mirroring an organization hierarchy, delegating the process of key generation, and authenticating identities of users to lower level PKGs.