Attribute-Based Conditional Proxy Re-Encryption with Chosen-Ciphertext Security

Abstract

Proxy re-encryption is a cryptographic primitive which enables a ciphertext encrypted under a delegator's public key to be translated into a ciphertext of a delegatee by a semitrusted proxy. Conditional proxy re-encryption (CPRE) is a variant of proxy re-encryption which allows the delegator to control the delegation of decryption rights with certain conditional value. The existing CPRE schemes left an open problem about how to construct CCA-secure CPRE schemes supporting Boolean predicates over conditions. In this paper, we propose attribute-based CPRE (AB-CPRE) in which the delegator could implement attributed-based control on the delegation of decryption rights by setting conditions in the form of access structure and attribute set. AB-CPRE is suitable for applications where fine-grained control of the decryption delegation is necessary. We formalize definitions and security notions for AB-CPRE and prove that the proposed scheme is chosen-ciphertext secure under the 3-Quotient Decision Bilinear Diffie-Hellman (3-QDBDH) assumption.

Fine-Grained Conditional Proxy Re-Encryption and Application

“…(2) Inheriting the advantages of ciphertext-policy ABE (over key-policy ABE), ciphertext-policy attribute based CPRE is more natural and flexible than its key-policy counterpart in encryption of cloud data, as the former allows the data owner to directly specify the access control policy associated with a ciphertext, under which the ciphertext can be decrypted. It deserves noting that while it is possible to transform ciphertext-policy ABE into key-policy ABE and vice versa [17], it is not clear whether the transformation techniques are applicable to keypolicy/ciphertext-policy attribute based CPRE schemes in [31,38]; our proposal is certainly not a direct transformation of those two schemes, though we have drawn on inspiration from [38].…”

“…Recently, Zhao et al [38] proposed an attribute-based CPRE scheme, which supports fine-grained conditions beyond keyword. Their scheme can be described as E(pk A , m, A)…”

“…However, the key-policy attribute based schemes in [31,38] suffer from two weaknesses. (1) Both schemes require to pre-define the total number N of attributes admitted by the system, and the size of the system's public key is linear to N .…”

Multiparty Access Control of Ciphertext Sharing in Cloud-Based Online Social Networks

“…The users identified by attributes could designate the proxy who can re-encrypt a ciphertext related with a certain access policy to another one with a different access policy. The CP-ABPRE scheme is a tuple of six algorithms [21]:…”

Analysis of Data Encryption Mechanisms for Searchable Encryption

“…Conditional ProxyRE [16] has been introduced to alleviate this problem. Furthermore, recently ABE has been integrated with ProxyRE [17]. However, advantages of using ABE to control delegation of decryption rights compared to just using ABE is insignificant and it only increases one additional level.…”