Post-quantum secure recipient revocable broadcast encryption supporting anonymity

Abstract

Recipient revocable broadcast encryption (RRevocBE), introduced by Susilo et al. is a cryptographic primitive which allows public revocation of users from encrypted message without decrypting it therefore with the help of RRevocBE we can revoke some users without knowledge of plaintext. We have proposed the first k-LWE based RRevocBE which is secure against post-quantum attack. All the existing similar constructions are bilinear pairing based. Hence, these are not secure in post-quantum cryptographic world. Moreover, our scheme achieves anonymity by concealing the user indices at the time of decryption. Further, it is adaptive secure and does not use random oracles in security proof. More interestingly, the secret key and ciphertext consists of single vector of size m + 1 where m is an integer. We also implemented this post quantum secure RRevocBE construction and achieved reasonable computation time which are given in Table 1. For 128 bit of security we have to select $n = 320, \log _{2}(p) \leq 18.85$, α = .0001 and m = 681. We computed the running time complexity of RRevocBE in terms of encryption, revoke and decryption time for 128-bit security level. We employed SageMath (version 9.2) for implementation with a workstation comprising an Intel Core i9 1.60 GHz processor with 64-bit Linux Lite (v 5.2) operating system. Results are documented in Table 1.