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A Compact Multi-Identity Fully Homomorphic Encryption Scheme Without Fresh Ciphertexts

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Titel: A Compact Multi-Identity Fully Homomorphic Encryption Scheme Without Fresh Ciphertexts
Autoren: Ziwei Wang, Ruwei Huang, Xiyi Wei
Quelle: Applied Sciences ; Volume 15 ; Issue 1 ; Pages: 473
Verlagsinformationen: Multidisciplinary Digital Publishing Institute
Publikationsjahr: 2025
Bestand: MDPI Open Access Publishing
Schlagwörter: fully homomorphic encryption, identity-based encryption, multi-identity, learning with errors, fresh ciphertext
Geographisches Schlagwort: agris
Beschreibung: The lattice-based multi-identity fully homomorphic encryption scheme combines the quantum security of lattice cryptography with the advantage of identity-based encryption. However, existing schemes face challenges such as large key sizes, inefficient ciphertext expansion processes, and reliance on outdated trapdoor designs, limiting their compactness and practicality. In this study, we propose a novel Compact Multi-Identity Fully Homomorphic Encryption Scheme (WZ-MIBFHE) that eliminates the need for fresh ciphertexts during expansion. First, we construct a compact identity-based encryption scheme by combining the YJW23 trapdoor and ABB10 under the standard model, proving its IND-sID-CPA security. The scheme is then adapted to ensure correctness and security when integrated with the decomposition method for ciphertext expansion. This adaptation also utilizes approximation errors to reduce overall noise. Finally, we expand the modified IBE scheme’s ciphertext using the decomposition method to construct the WZ-MIBFHE scheme. Compared to existing methods, WZ-MIBFHE reduces the lattice dimension to nlogq+logbq, improves public and private key sizes, and significantly lowers ciphertext expansion rates by removing the need for fresh ciphertexts. These improvements enhance both the compactness and efficiency of the scheme, making it a promising solution for multi-identity homomorphic encryption.
Publikationsart: text
Dateibeschreibung: application/pdf
Sprache: English
Relation: https://dx.doi.org/10.3390/app15010473
DOI: 10.3390/app15010473
Verfügbarkeit: https://doi.org/10.3390/app15010473
Rights: https://creativecommons.org/licenses/by/4.0/
Dokumentencode: edsbas.ABD87299
Datenbank: BASE
Beschreibung
Abstract:The lattice-based multi-identity fully homomorphic encryption scheme combines the quantum security of lattice cryptography with the advantage of identity-based encryption. However, existing schemes face challenges such as large key sizes, inefficient ciphertext expansion processes, and reliance on outdated trapdoor designs, limiting their compactness and practicality. In this study, we propose a novel Compact Multi-Identity Fully Homomorphic Encryption Scheme (WZ-MIBFHE) that eliminates the need for fresh ciphertexts during expansion. First, we construct a compact identity-based encryption scheme by combining the YJW23 trapdoor and ABB10 under the standard model, proving its IND-sID-CPA security. The scheme is then adapted to ensure correctness and security when integrated with the decomposition method for ciphertext expansion. This adaptation also utilizes approximation errors to reduce overall noise. Finally, we expand the modified IBE scheme’s ciphertext using the decomposition method to construct the WZ-MIBFHE scheme. Compared to existing methods, WZ-MIBFHE reduces the lattice dimension to nlogq+logbq, improves public and private key sizes, and significantly lowers ciphertext expansion rates by removing the need for fresh ciphertexts. These improvements enhance both the compactness and efficiency of the scheme, making it a promising solution for multi-identity homomorphic encryption.
DOI:10.3390/app15010473