Attribute-Based Keyword Search Encryption Scheme with Verifiable Ciphertext via Blockchains

In order to realize the sharing of data by multiple users on the blockchain, this paper proposes an attribute-based searchable encryption with verifiable ciphertext scheme via blockchain. The scheme uses the public key algorithm to encrypt the keyword, the attribute-based encryption algorithm to encrypt the symmetric key, and the symmetric key to encrypt the file. The keyword index is stored on the blockchain, and the ciphertext of the symmetric key and file are stored on the cloud server. The scheme uses searchable encryption technology to achieve secure search on the blockchain, uses the immutability of the blockchain to ensure the security of the keyword ciphertext, uses verify algorithm guarantees the integrity of the data on the cloud. When the user’s attributes need to be changed or the ciphertext access structure is changed, the scheme uses proxy re-encryption technology to implement the user’s attribute revocation, and the authority center is responsible for the whole attribute revocation process. The security proof shows that the scheme can achieve ciphertext security, keyword security and anti-collusion. In addition, the numerical results show that the proposed scheme is effective.