Attribute-based re-encryption method for implementing fine-grained attribute cancellation

Abstract

The invention discloses an attribute-based re-encryption method for implementing fine-grained attribute cancellation, and belongs to the field of information security. The method mainly comprises thesteps of A, system initiation; B, encryption; and C, re-encryption: C1, user cancellation information; C2, primary re-encryption; and C3, subsequent re-encryption. According to the method provided bythe invention, an attribute cancellation list is introduced, so that when attribute cancellation occurs in the system, an encryption party can only compute and update a sub-ciphertext corresponding tothe cancelled attribute via an re-encryption algorithm, and does not re-compute the sub-ciphertexts corresponding to the non-cancelled attributes, so that the computation complexity is reduced without affecting the access permissions of the other non-cancelled users at the same time, and the fine-grained attribute permission cancellation is achieved. During the re-encryption process, re-encryption of the file is implemented via simple multi-point operation and modular exponential operation, the complex and time-consuming composite order bilinear operation and multi-linear operation are avoided, the computation complexity is low, and the cancellation efficiency is high.

Description

technical field [0001] The invention relates to an attribute-based re-encryption method for realizing fine-grained attribute revocation. Background technique [0002] The vigorous development of cloud computing and other big data applications has solved the current calculation and storage problems of massive information and data; the arrival of the cloud computing era shows that information technology is rapidly moving towards the road of scale, intensification and specialization. However, cloud computing has problems such as unstable security boundaries, separation of data storage usage rights, and easy disclosure of user privacy information; therefore, how to protect data confidentiality and realize anonymous identity authentication and access control functions has become a very realistic and urgent problem to be solved . Attribute-based (attribute-based) encryption scheme uses attributes to divide users in a fine-grained manner; and uses specific access policies to encry...

AI Technical Summary

Problems solved by technology

In the actual application environment, there are unavoidable situations such as attribute expiration, key leakage, and attribute permission change; however, most existing attribute-based encryption methods often affect the system when revoking a user's attribute permission. other users who have this attribute in the database, it is difficult to revoke the user's attribute permissions efficiently and fine-grained; as a result, when the user's attribute permissions change, the user's access permissions cannot be updated in time to ensure that they cannot use the original key to decrypt the ciphertext

[0003] Wang Pengpian et al. (a CP-ABE scheme that supports complete fine-grained attribute revocation [J]. Journal of Software, 2012, 23(10):2805-2816) proposed a CP that supports complete fine-grained attribute revocation in 2012. -ABE method; this method uses composite order bilinear groups, introduces the idea of ​​double system encryption and binary tree, and can realize the function of fine-grained attribute revocation; this method includes four stages: initialization, key generation, encryption, and decryption; when When the user's attribute permission is revoked, the encryption party uses the re-encryption algorithm to process the existing ciphertext, so that the user whose attribute permission has been revoked cannot use the original key to decrypt the file corresponding to the ciphertext

However, the decryption process of this method requires a lot of time-consuming composite order bilinear pairing operations, and the efficiency is not high; in addition, the length of the ciphertext generated by this method is longer, reaching (3|B|+2r+2)| G 1 |bit, where |B| represents the number of attributes declared in the access policy, r represents the number of revocation events, and |G 1 |Indicates the length of elements in the exchange group on the elliptic curve, which greatly increases the communication burden of the system, so it is less practical

[0004] Shi et al. (Directly revocable key-policy attribute-based encryption with verifiable ciphertext delegation[J]. Information Sciences, 2015, 295:221-231) proposed a key-policy-based attribute-based encryption that supports direct attribute revocation based on multi-linear mapping. Encryption method; however, this method can only realize the revocation of all user attributes, and the revocation granularity is relatively coarse; and this method requires a large number of multi-linear pairing operations in the process of encryption, re-encryption, and decryption, and the efficiency of attribute revocation is low; therefore, it is not applicable In environments with limited computing resources

In addition, the way that the decryption policy is bound to the user key, and the attribute is bound to the ciphertext limits the flexibility and practicability of the method