Choose an integrity check
For an upload you control, compute a checksum from the source and compare it with a checksum returned or stored by the service. Confirm which checksum algorithm and upload mode are supported; multipart workflows may calculate or expose checksums differently.
Also verify the expected object size and metadata. A matching size alone cannot detect every content change, while a checksum comparison should use the same byte representation and algorithm at both ends.
Plan verification for the access path
Read the stored object back in a test or verification flow and validate it when end-to-end assurance is required. For large objects, use a streaming calculation rather than loading the entire body into memory.
Keep verification results associated with the object version or upload identifier, and alert on mismatches. Define what happens on failure—such as quarantine and retry—without replacing a known-good object until the new copy passes validation.