Verifiable Random Functions from Identity-Based Key Encapsulation

We propose a methodology to construct verifiable random functions from a class of identity based key encapsulation mechanisms (IB-KEM) that we call VRF suitable. Informally, an IB-KEM is VRF suitable if it provides what we call unique decapsulation (i.e. given a ciphertext C produced with respect to an identity ID, all the secret keys corresponding to identity ID , decapsulate to the same value, even if ID = ID ) and it satisfies an additional property that we call pseudorandom decapsulation. In a nutshell, pseudorandom decapsulation means that if one decapsulate a ciphertext C, produced with respect to an identity ID, using the decryption key corresponding to any other identity ID the resulting value looks random to a polynomially bounded observer. Interestingly, we show that most known IB-KEMs already achieve pseudorandom decapsulation. Our construction is of interest both from a theoretical and a practical perspective. Indeed, apart from establishing a connection between two seeming...

• Type: Conference
• Year: 2009
• Where: EUROCRYPT
• Authors: Michel Abdalla, Dario Catalano, Dario Fiore
• Keywords: Cryptography, Decryption Key Corresponding, EUROCRYPT 2009, Identity Id, Pseudorandom Decapsulation