Secure Data Integrity Check Based on Verified Public Key Encryption with Equality Test for Multi-Cloud Storage

Cloud computing eliminates the need for local hardware, addressing the challenge of high computing expenses. However, entrusting data to the cloud may pose the risk of unintentional data loss. Using multiple copies and multi-cloud servers is promising because even if the data on one cloud storage server is compromised, the data proprietor can retrieve the information from alternate cloud storage servers. To protect data security, data needs to be encrypted before uploading to the cloud. However, users cannot directly confirm whether their encrypted documents and copies are stored securely and with integrity on cloud servers. To verify data copies on remote servers without downloading and decrypting, we propose Public Verification Public Key Encryption with Equality Test (PVPKEET). Under PVPKEET, users upload encrypted data to cloud servers, and then the test result and proof will be provided by the cloud server without decryption. The publicly verified proof can be examined by all users, allowing everyone to witness the copies stored correctly. Our approach is resistant to chosen-plaintext attacks and is verifiable. A comparison with prior research demonstrates the efficiency and feasibility of our design.