Welcome to the resource topic for 2023/780
Title:
An Anonymous Multi-receiver Certificateless Hybrid Signcryption (AMCLHS) using mKEM-DEM for Broadcast Communication
Authors: Alia Umrani, Apurva K Vangujar, Paolo Palmieri
Abstract:Confidentiality, authentication, and anonymity are the fundamental security requirements in broadcast communication that can be achieved by Digital Signature (DS), encryption, and pseudo-anonymous identity techniques. Signcryption offer both DS and encryption in a single logical step with high efficiency. Similarly, anonymous multireceiver signcryption ensure receiver privacy by generating identical ciphertext for multiple receivers while keeping their identities private. While signcryption is a significant improvement over “sign then encrypt”, it still incurs higher computational and communication cost and does not provide the required level of security.
In this paper, we propose a multiple-recipient Key Encapsulation Mechanism (mKEM) - Data Encapsulation Mechanism (DEM) based Anonymous Multireceiver Certificateless Hybrid Signcryption (AMCLHS). The AMCLHS uses a combination of symmetric key and asymmetric key cryptography to signcrypt an arbitrary length message in broadcast communication and has two unique settings as follows:
Pseudo-Identity PID Settings: We introduce a new algorithmic step in AMCLHS construction where each user (sender and receiver) is assigned a PID to enable the sender to signcrypt identical messages for multiple receivers while keeping the identities of other receivers anonymous.
The receiver anonymity is achieved by choosing random Real-Identity (ID_R) to generate PID of the users in key generation algorithm of AMCLHS scheme. Our approach relies on the Elliptic Curve Discrete Logarithm (ECDL) hardness assumptions, the hash function, and verification-based secret key of the Register Authority (RA), using time Delta T.
mKEM-DEM Settings: We introduce the first construction that achieves optimal ciphertext from the Diffie-Hellman (DH) assumption using mKEM-DEM for Signcryption. Our scheme uses mKEM to generate a symmetric key for multiple-receivers and DEM to signcrypt message using the previously generated symmetric key and the sender’s private key. mKEM for key setup and Signcryption for confidentiality and forward security, and DEM for key generation and unsigncryption for indistinguishability under Indistinguishability against Chosen Ciphertext Attack (IND-CCA2).
Our scheme relies on DH and Bilinear Pairing (BP) assumption and uses a single key for all messages, which minimizes ciphertext length and ultimately reduces complexity overhead.
The scheme operates in a multireceiver certificateless environment, preventing the key escrow problem, and demonstrates cryptographic notions for Indistinguishability under Chosen-Ciphertext Attack (IND-CCA2) and Existential Unforgeability against Chosen Message Attack (EUF-CMA) for Type-I and Type-II adversaries under q-Decisional Bilinear Diffie-Hellman Inversion (q-DBDHI) and ECDL hard assumptions. We compare the proposed scheme with existing multireceiver hybrid signcryption schemes in terms of computation cost, communication cost, and security requirements. We show that, compared to existing multireceiver schemes which has overall cost of O(n^2), our scheme is computationally more efficient and has optimal communication cost, with signcryption cost linear O(n) to the number of designated receivers while the unsigncryption cost remains constant O(1). Our scheme achieves confidentiality, authentication, anonymity, and simultaneously achieves unlinkability, non-repudiation, and forward security.
ePrint: https://eprint.iacr.org/2023/780
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