Public-Key Revocation and Tracing Schemes with Subset Difference Methods Revisited
Kwangsu Lee, Woo Kwon Koo, Dong Hoon Lee, Jong Hwan Park · 2015
Trace and revoke is broadcast encryption with the traitor tracing functionality. It is a very powerful primitive since it can revoke users whose private keys are compromised by finding them using a tracing algorithm if a pirate decoder is given. Public-key trace and revoke (PKTR) is a special type of trace and revoke such that anyone can run the tracing algorithm and anyone can create an encrypted message by using a public key. Although public-key trace and revoke schemes are attractive tools, the currently known PKTR schemes are a little bit inefficient in terms of the private key size and the public key size compared with public-key broadcast encryption schemes. In this paper, we propose a new technique to construct an efficient PKTR scheme by using the subset cover framework. First, we introduce a new concept of public-key encryption named single revocation encryption (SRE) and propose an efficient SRE scheme in the random oracle model. The universe of SRE consists of many groups and each group consists of many members. A user in SRE is represented as a group that he belongs and a member in the group. In SRE, a sender can create a ciphertext for a specified group where one member in the group is revoked, and a receiver can decrypt the ciphertext if he belongs to the group in the ciphertext and he is not revoked in the group.