Cloud storage provides users with outsourcing file storage. However, as the number of data outsourcing surges, deduplication has become critical. At present, a quite effective and commonly used method for data compression is deduplication, that is, to identify redundant data blocks in the data and store only one copy of them. The previous scheme can satisfy different users to encrypt the same file into the same ciphertext, which exposes the consistency of the file. Later, another scheme is proposed in which a centralized server is taken as a deduplication aid. However, with the increase in the number of users, the deduplication efficiency also reduces. In view of the current security and low deduplication efficiency of cloud storage, this study proposes a cross-domain deduplication scheme. The proposed scheme generates random tags and fixed-length random ciphertext for each data to ensure data confidentiality in the case of cross-domain deduplication, resist violent attacks and protect the information equality from being disclosed. In addition, the implementation of the proposed scheme and its function are analyzed. The safety analysis shows that the scheme realizes the privacy protection regarding data content, equality information and data integrity while resisting brute force attacks. The performance analysis demonstrates that it outperforms the existing scheme in terms of repeated search calculation cost and time complexity, which enables lightweight characteristics.