The ciphertext-policy attribute-based proxy re-encryption (CP-ABPRE) scheme supports access control and can transform a ciphertext under an access policy to a ciphertext under another access policy without decrypting the ciphertexts, which is flexible and efficient for cloud sharing. The existing CP-ABPRE schemes are constructed by bilinear pairing or multi-linear maps which are fragile when the post-quantum future comes. This paper presents an efficient unidirectional single-hop CP-ABPRE scheme with small public parameters from a lattice. For the transformation between two access structures, they are required to be disjoint. This paper uses the trapdoor sampling technique to generate the decryption key and the re-encryption key in constructing the scheme, and uses the decompose vectors technique to produce the re-encrypted ciphertexts in order to control their noise. Finally, we extended the scheme to a unidirectional single-hop CP-ABPRE scheme with keyword search for searching the encrypted data. Both schemes were proved secure under the learning with errors assumption, which is widely believed to be secure in quantum computer attacks. To the best of our knowledge, our scheme is the first CP-ABPRE scheme based on the learning with errors assumption.
The ciphertext-policy attribute-based proxy re-encryption (CP-ABPRE) scheme supports access control and can transform a ciphertext under an access policy to a ciphertext under another access policy without decrypting the ciphertexts, which is flexible and efficient for cloud sharing. The existing CP-ABPRE schemes are constructed by bilinear pairing or multi-linear maps which are fragile when the post-quantum future comes. This paper presents an efficient unidirectional single-hop CP-ABPRE scheme with small public parameters from a lattice. For the transformation between two access structures, they are required to be disjoint. This paper uses the trapdoor sampling technique to generate the decryption key and the re-encryption key in constructing the scheme, and uses the decompose vectors technique to produce the re-encrypted ciphertexts in order to control their noise. Finally, we extended the scheme to a unidirectional single-hop CP-ABPRE scheme with keyword search for searching the encrypted data. Both schemes were proved secure under the learning with errors assumption, which is widely believed to be secure in quantum computer attacks. To the best of our knowledge, our scheme is the first CP-ABPRE scheme based on the learning with errors assumption.
Cloud-based services have powerful storage functions and can provide accurate computation. However, the question of how to guarantee cloud-based services access control and achieve data sharing security has always been a research highlight. Although the attribute-based proxy re-encryption (ABPRE) schemes based on number theory can solve this problem, it is still difficult to resist quantum attacks and have limited expression capabilities. To address these issues, we present a novel linear secret sharing schemes (LSSS) matrix-based ABPRE scheme with the fine-grained policy on the lattice in the research. Additionally, to detect the activities of illegal proxies, homomorphic signature (HS) technology is introduced to realize the verifiability of re-encryption. Moreover, the non-interactivity, unidirectionality, proxy transparency, multi-use, and anti-quantum attack characteristics of our system are all advantageous. Besides, it can efficiently prevent the loss of processing power brought on by repetitive authorisation and can enable precise and safe data sharing in the cloud. Furthermore, under the standard model, the proposed learning with errors (LWE)-based scheme was proven to be IND-sCPA secure.
Data is typically encrypted before transmission to a cloud server to safeguard user privacy. However, such encryption prevents the server from performing searches on the data, necessitating the introduction of novel cryptographic primitives, such as public key encryption with multi-ciphertext equality test (PKEMET). PKEMET allows the cloud server to execute a single equality test on multiple ciphertexts, determining if the underlying messages are identical disclosing any extra information. Ciphertext-policy attribute-based encryption (CP-ABE) facilitates secure and efficient data sharing in cloud computing environments by supporting fine-grained access control and flexible encryption. In this work, we integrate the concepts of PKEMET and CP-ABE, introducing a novel cryptographic primitive of CP-ABE with multi-ciphertext equality test (CP-ABEMET). We present the first quantum-resistant CP-ABEMET scheme based on the learning with errors (LWE) problem. This scheme enables the receiver to delegate the cloud server to perform a single equality test among multiple messages encrypted under distinct access policies. Importantly, during the multi-ciphertexts equality test, the server gains no knowledge of the encrypted messages. Furthermore, our proposed scheme not only achieves traditional indistinguishability against chosen plaintext attack (IND-CPA) and one-way against chosen plaintext attack (OW-CPA) security but is also proven to be number secure and resilient against collusion attacks. Finally, a comparative performance analysis between our CP-ABEMET and existing equality test schemes demonstrates that our approach is more practical, efficient, and secure.
This article deals with designing an efficient post-quantum lattice based encryption scheme that relies on the multi-authority Ciphertext-Policy Attribute-Based Encryption (CP-ABE). The security of the proposed scheme is based on the hardness of the ring learning with errors (RLWE) problem. The construction of the proposed scheme is done using the Shamir's threshold secret sharing along with the Lagrange interpolation during the key generation and decryption processes in order to achieve the segmentation and restoration of private keys. A comparative study with the existing state of art schemes has been performed to show the feasibility and efficiency of the proposed scheme. Furthermore, experiments on the proposed scheme have been conducted to illustrate the computational time required during the key generation, encryption and decryption processes.
Ciphertext policy attribute-based encryption (CP-ABE) is a promising cryptographic technology that provides fine-grained access control as well as data confidentiality. It enables one sender to encrypt the data for more receivers, and to specify a policy on who can decrypt the ciphertext using his/her attributes alone. However, most existing ABE schemes are constructed on bilinear maps and they cannot resist quantum attacks. In this paper, we propose a multi-authority CP-ABE (MA-CPABE) scheme on ideal lattices which is still secure in post-quantum era. On one hand, multiple attribute authorities are required when user's attributes cannot be managed by a central authority. On the other hand, compared with generic lattice, the ideal lattice has extra algebraic structure and can be used to construct more efficient cryptographic applications. By adding some virtual attributes for each authority, our scheme can support flexible threshold access policy. Security analysis shows that the proposed scheme is secure against chosen plaintext attack (CPA) in the standard model under the ring learning with errors (R-LWE) assumption.
To protect the privacy of cloud data, encryption before uploading provides a solution. However, searching for target data in ciphertext takes effort. Therefore, searchable encryption has become an important research topic. On the other hand, since the advancement of quantum computers will lead to the crisis of cracking traditional encryption algorithms, it is necessary to design encryption schemes that can resist quantum attacks. Therefore, we propose a multi-keyword searchable identity-based proxy re-encryption scheme from lattices. In addition to resisting quantum attacks, the proposed scheme uses several cryptographic techniques to improve encryption efficiency. First, identity-based encryption is used to reduce the computation and transmission costs caused by certificates. Second, the proposed scheme uses proxy re-encryption to achieve the purpose of outsourced computing, allowing the proxy server to reduce the computation and transmission costs of the users. Third, the proposed multi-keyword searchable encryption can provide AND and OR operators to increase the flexibility of searchability. Moreover, the access structure of the proposed scheme is not based on a linear secret sharing scheme (LSSS), avoiding the errors caused by an LSSS-based structure in decryption or search results. Finally, we also give formal security proof of the proposed scheme under the decisional learning with errors assumption.
Identity-based proxy re-encryption (IB-PRE) is a kind of public key cryptography that allows a proxy to convert the ciphertext based on Alice’s identity into another ciphertext of the same message for Bob. It has important applications in cloud computing, distributed systems and secure e-mail forwarding. So far, the existing lattice-based IB-PRE schemes are designed on the general lattice and their security is based on the learning with errors (LWE) assumption. In this paper, we propose an IB-PRE scheme over NTRU lattices with the desirable properties of anonymity, unidirectionality, backward collusion safeness and multi-hop. Our IB-PRE scheme is provable secure under adaptive chosen-plaintext and adaptive chosen-identity attacks. And, in the random oracle model, the security of our scheme is based on the decisional Ring-LWE assumption. Besides, the key and ciphertext sizes of our IB-PRE scheme are short, only one or two ring elements, and our scheme could encrypt n bits in each encryption process.