A Public Key Identity-Based Revocation Scheme:

Multi-Recipient Encryption allows users to send secure messages to any chosen set of registered users. In ACISP’21, Blazy et al. proposed a multi-recipient encryption with attribute-hiding revocation where ciphertexts do not reveal any information about the users that have been revoked. However, their work only achieved secret key instantiations of multi-recipient encryption with attribute-hiding revocation. Our work gives the first public-key Identity-Based Revocation with fully attribute-hiding security and computational function privacy. For this purpose, we construct the first fully attribute-hiding Non-zero Inner-Product Encryption (NIPE) with computational function privacy. Toward this goal, we also study the relationship between Zero Inner-Product Encryption (ZIPE) and Non-Zero Inner-Product Encryption (NIPE). We propose a compiler to convert a fully attribute-hiding secure ZIPE into a fully attribute-hiding secure NIPE. We then construct the ZIPE with the necessary security properties. This construction along with the compiler produces the first NIPE with the said full attribute-hiding security. We also argue that this NIPE construction achieves computational function privacy due to a falsifiable assumption. A variation of Attrapadung and Libert’s transformation (PKC’11) on our NIPE thus achieves the first attribute-hiding identity-based revocation (IBR) scheme in the standard model. We further show that our IBR construction achieves function privacy under another novel assumption which we show to be falsifiable.