An attribute-based lightweight cloud data access control using hypergraph structure

Abstract

Cloud file storage systems are the current trend of enterprises and also of individual users. Due to the malicious or unauthorized users, file sharing among the cloud users has become the biggest challenge in the recent times. Attribute-based signcryption (ABSC) is known as the versatile cryptographic primitive which achieves the fine-grained access control over robust cloud storage. ABSC combines attribute-based encryption (ABE) and attribute-based signatures to achieve privacy-oriented confidentiality along with the authenticity. Unfortunately, most of the present ABE and ABSC schemes leverage heavy computational overheads against the key length, the ciphertext size or the expressive access structures used. In this paper, a new ABSC scheme is devised to reduce computational overheads, more particularly, at cloud by introducing the more expressive hypergraph access structure, Attribute HyperGraph. On a positive note, the proposed system outperforms and shows less cloud computational timing without exponentiations unlike Deng et al. (IEEE Access 6:39473–39486, 2018. https://doi.org/10.1109/ACCESS.2018.2843778), Liu et al. (Future Gener Comput Syst 52:67–76, 2015. https://doi.org/10.1016/j.future.2014.10.014) and Li et al. (IEEE Trans Parallel Distrib Syst 25(8):2201–2210, 2014. https://doi.org/10.1109/TPDS.2013.271) schemes. Subsequently, the system does not incur any cryptographic computations associated with designcryption at cloud unlike Deng et al. (2018).

Appendices

Appendix

1.1 Security algorithmic phases of AHG-CPABSC scheme

This appendix section is dedicated to list our security algorithms. Security proof is not within the scope of this paper and will be extended as the future work.

Signature used in the proposed system

The signature used by the system follows Rivest–Shamir–Adleman (RSA) implementation public key cryptography standards (PKCS 1) [29]. The system generates the public key and private key as given follows:

• 1. Two random prime numbers (namely $p$ and $q$) are selected

• 2. $\lambda (n)$ is calculated as $\lambda (n) = {\text{lcm}}(p - 1,q - 1)$, where $\lambda$ is Carmichael’s quotient function, $n = pq$ and ${\text{lcm}}$ is least common multiple

• 3. An integer $e$ is chosen such that $1 < e < \lambda (n)$ and $\gcd (e,\lambda (n)) = 1$, where ${ \gcd }$ is the greater common divisor

• 4. An integer $s$ is computed such that $se \equiv 1 \;\bmod \;\lambda (n)$

Public key $\upsilon = (e,n)$

Private key $r = (d,n)$

The steps for signing the data are as follows:

• 1. The hash of the plaintext is calculated using SHA256 algorithm

• 2. The hash $h$ is encrypted using the RSA private key of the signer (sender) to obtain the signature. $S = h^{d} \;\bmod \; n$

The steps for verifying the data are as follows:

• 1. The hash $h^{\prime }$ of the plaintext is calculated using SHA256 algorithm

• 2. The hash h is obtained by decrypting the signature S using RSA public key of the signer (sender). $h = S^{e} \;\bmod \;n$

• 3. The signature is verified if $h$ and $h^{\prime }$ are equal.