Attribute Revocable Multi-Authority Attribute-Based Encryption with Forward Secrecy for Cloud Storage

Abstract

SUMMARYInternet of Things (IoT) has been widely applied in various fields. IoT data can also be put to cloud, but there are still concerns regarding security and privacy. Ciphertext-Policy Attribute-Based Encryption (CP-ABE) is attracted attention in cloud storage as a suitable encryption scheme for confidential data share and transmission. In CP-ABE, the secret key of a user is associated with a set of attributes; when attributes satisfy the access structure, the ciphertext is able to be decrypted. It is necessary that multiple authorities issue and manage secret keys independently. Authorities that generate the secret key can be regarded as managing the attributes of a user in CP-ABE. CP-ABE schemes that have multiple authorities have been proposed. The other hand, it should consider that a user's operation at the terminals is not necessary when a user drop an attribute and key is updated and the design of the communication system is a simple. In this paper, we propose CP-ABE scheme that have multiple key authorities and can revoke attribute immediately with no updating user's secret key for attribute revocation. In addition, the length of ciphertext is fixed. The proposed scheme is IND-CPA secure in DBDH assumption under the standard model. We compare the proposed scheme and the other CP-ABE schemes and show that the proposed scheme is more suitable for cloud storage. key words: ciphertext-policy attribute-based encryption, multiple key authorities, attribute revocation, forward secrecy

SEM-ACSIT: Secure and Efficient Multiauthority Access Control for IoT Cloud Storage

“…The scheme can efficiently attain multi-level privacy preservation without extra signatures. Nomura et al [25] proposed a multi-authority attribute-based encryption scheme with attribute revocation for cloud storage. It can revoke an attribute without updating a user's secret key.…”

vFAC: Fine-Grained Access Control with Versatility for Cloud Storage

“…Let l denote the number of rows of the access matrix, |I| (|I| ≤ l) denote the number of rows used for decryption in the access matrix, P denote bilinear pair operation, and E denote exponential operation. In TABLE II, we found that the schemes in [16]- [18], [22] have no offline encryption mechanism, which cause the number of operations in encryption phase linearly increasing with l. In [16], [18], [22], the user directly decrypts the original ciphertext, so the exponential operations and the number of bilinear pair operations also linearly increase with |I| in the decryption phase, leading to high computational complexity. In the decryption process of vFAC, only one exponent operation is involved.…”

“…Therefore, the length of public/private key of AA is linearly related to |U |. The users private key in [16], [18], [20], [22] is directly generated by AA based on the user's attributes, so the length of private key is linearly related to |S|. When the number of attributes increases, the user's storage cost increases too.…”

“…YMCZZ in [18] is accountable, but its method of solving the key escrow problem will cause the waste of resources, which is difficult to implement under actual conditions. Besides, the schemes in [18], [20], [22] may have the problem of system construction if too many attributes are added to attribute authorities due to lack in the feature of large universe. Because our proposed vFAC provides all the features listed in table I, it is more comprehensive than other schemes.…”

“…In [20], [22], the length of the public/private key of each AA is linearly related to the number of its attributes. Therefore, the length of public/private key of AA is linearly related to |U |.…”