Identity-based Matchmaking Encryption (IB-ME) is a new form of encryption that enables anonymous communication by specifying identities for both sender and receiver. Its applications in network services put forward higher requirements for the security of IB-ME. According to existing research, the security definition of IB-ME against chosen-plaintext attacks or chosen-ciphertext attacks is still vague. In this paper, we give the first clear definition of CCA-security of IB-ME and propose the first CCA-secure IB-ME scheme under the standard assumptions in the standard model. We first construct a CCA-secure anonymous IBE scheme by combining anonymous hierarchical IBE with CHK CPA-CCA conversion at EUROCRYPT’04. Our proposed IB-ME scheme is a variant of two-level IBE, whose first level is this CCA-secure anonymous IBE, and the second level is a signature derived from this IBE. And its security is proven under standard assumptions and standard model.
Indistinguishability Obfuscation from Well-Founded Assumptions
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It is tricky to determine whether two ciphertexts contain the same message when the messages are encrypted with different public keys. public key encryption with equality test (PKEET) addresses this problem without decryption. By integrating PKEET with identity-based encryption, identity-based encryption with equality test (IBEET) simplifies the certificate management in PKEET. In this paper, we first propose an IBEET scheme that can resist offline message recovery attacks (OMRA) and requires neither the dual-tester setting nor the group mechanism. With the help of some mathematical assumptions, we demonstrate the security of our scheme. Experiment results reveal that our scheme is efficient. From the perspective of usability, we explain why our scheme is more appropriate to be applied in healthcare social Apps than other OMRA-resistant schemes.
Anonymous Identity Based Encryption (AIBET) scheme allows a tracer to use the tracing key to reveal the recipient's identity from the ciphertext while keeping other data anonymous. This special feature makes AIBET a promising solution to distributed IoT data security since it can preserve both the privacy and the anonymity of a communication network but still give the server the ability to revoke the anonymity of some specific users in necessary situations (such as when their illegal behavior are detected). In this paper, we construct an efficient quantum-safe Hierarchical Identity-Based cryptosystem with Traceable Identities (AHIBET) with fully anonymous ciphertexts. We prove the security of our AHIBET scheme under the Learning with Errors (LWE) problem in the standard model.
Spatial encryption (SE), which involves encryption and decryption with affine/vector objects, was introduced by Boneh and Hamburg at Asiacrypt 2008. Since its introduction, SE has been shown as a versatile and elegant tool for implementing many other important primitives such as (Hierarchical) Identity-based Encryption ((H)IBE), Broadcast (H)IBE, Attribute-based Encryption, and Forward-secure cryptosystems. This paper revisits SE toward a more compact construction in the lattice setting. In doing that, we introduce a novel primitive called Delegatable Multiple Inner Product Encryption (DMIPE). It is a delegatable generalization of Inner Product Encryption (IPE) but different from the Hierarchical IPE (HIPE) (Okamoto and Takashima at Asiacrypt 2009). We point out that DMIPE and SE are equivalent in the sense that there are security-preserving conversions between them. As a proof of concept, we then successfully instantiate a concrete DMIPE construction relying on the hardness of the dec
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