Operation scenarios:

An error may occur when data is transmitted between the client and the server. The integrity of uploaded data can be guaranteed by MD5 authentication. Data can be uploaded successfully only when the MD5 checksum of data received by the server is consistent with that set by the user.

Prerequisites:

l Upload check scenario: Users calculate the MD5 checksum of the object to be uploaded locally.

l Download check scenario: The MD5 checksum of the object is set by customizing metadata when it is uploaded.

Operation steps:

l Upload check scenario:

Step 1: Users calculate the MD5 checksum of the file to be uploaded locally and make a record.

Step 2: When uploading an object, set Content-MD5 of the request message as the locally calculated checksum. The message is as follows.

PUT /{Bucket}/{Key} HTTP/1.1

Host: xxx-zos.ctyun.cn

X-Amz-Content-Sha256: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855

X-Amz-Date: 20220406T134209Z

Authorization: authorization string

Content-MD5: ContentMD5

Body

Step 3: After receiving the upload request, the server will automatically check the MD5 of the object. The upload will succeed if the checksum is consistent. Otherwise the upload will fail.

l Download check scenario:

Step 1: The user has recorded the metadata of the object by customizing the metadata when uploading the object. By carrying the following field identifier in the request parameter

x-amz-meta-<…>: MD5

Step 2: After downloading the data, the user can get the MD5 information of custom metadata from the downloaded response message. At this point,

the user can recalculate the checksum of the object and compare it with the custom metadata, so as to verify whether the checksum of the downloaded object is consistent with that of the original object.

Zettabyte Object Storage