Аннотация:Cloud technologies are widely used for storage services. However, the single cloud cannot ensure the reliability of data. To solve the security issue, we present a multi-cloud based storage architecture called WA-RRNS that combines weighted access scheme and threshold secret sharing redundant residue number system with multiple failure detection/recovery mechanisms and homomorphic ciphers. For better tradeoffs between security and performance, WA-RRNS uses parameters to adjust redundancy, encryption-decryption speed, and data loss probability. Theoretical and experimental analysis with real data shows that our approach provides a secure way to mitigate the uncertainty of the use of untrusted and not reliable cloud storage.