Supplementary Information

A starting digest file is generated after you start verifying trace file integrity. In a starting digest file, the following fields related to the previous digest file will be left empty:

• previous_digest_bucket
• previous_digest_object
• previous_digest_hash_value
• previous_digest_hash_algorithm
• previous_digest_signature

CTS will still send a digest file even if no operations have occurred in your account within the one-hour time period recorded by the digest file. The last field log_files:[] of the digest file will be left empty. It helps you to confirm that no trace files have been sent within the one-hour time period recorded by the digest file.

A digest file contains the digital signature and Hash value of the previous digest file (if any) so that a chain is formed. You can verify digest files successively within a specified time, starting with the latest one.

A digest file is sent to the OBS bucket that stores trace files recorded in the file.

A digest file is stored in a folder different from that for trace files, making it easy for you to execute fine-grained security policies.