Efficient biometric identity-based encryption

As a special case of public key encryption, identity-based encryption (IBE) takes any public known information as public key for encryption and then decrypts a ciphertext by a well-generated private key from private key generator (PKG). Unlike the traditional IBE using a text-based identity (e-mail, etc.) as public key, in this paper, we aim to design a secure, time-saving and space-saving biometric identity-based encryption (BIBE) regarding the biometric-based identity (face, etc.) as public key. To overcome the challenge introduced by the fuzziness of biometric identities, First, we propose a provable-secure inner-product encryption (IPE) with short ciphertext and show the IPE is indistinguishable against selective identity, adaptive chosen-plaintext attack (IND-sID-CPA). Then, we construct a distance-based encryption (DBE) leveraging the proposed IPE and prove that the DBE captures the same security with the underlying IPE. Furthermore, we optimize the proposed DBE so that it also has short private key. We theoretically analyze the overhead of IPE, DBE, and optimized DBE (ODBE) in terms of time, space, and communication complexities. We also conduct experiments to measure the time and space costs of the proposed ODBE, and experimental results validate its effectiveness and efficiency.