Yutaka Kawai

Learn More
In this paper, we propose a reasonable definition of predicate-hiding inner product en-cryption (IPE) in a public key setting, which we call inner product encryption with cipher-text conversion (IPE-CC), where original ciphertexts are converted to predicate-searchable ones by an helper in possession of a conversion key. We then define a notion of full(More)
Secret handshake allows two members in the same group to authenticate each other secretly. In previous works of secret handshake schemes, two types of anonymities against the group authority (GA) of a group G are discussed: 1)Even GA cannot identify members, namely nobody can identify them (No-Traceability), 2)Only GA can identify members (Traceability). In(More)
In this paper, we introduce a general notion of functional proxy-re-encryption (F-PRE), where a wide class of functional encryption (FE) is combined with proxy-re-encryption (PRE) mechanism. The PRE encryption system should reveal minimal information to a proxy, in particular, hiding parameters of re-encryption keys and of original ciphertexts which he(More)