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Hash Calculation

Last updated: 2024-10-24 18:41:53

Overview
Hash calculation is a solution that allows users to verify the integrity of cloud objects that Tencent Cloud Object Storage (COS) provides based on Serverless Cloud Function (SCF). When an object is uploaded to COS, its hash will be auto-calculated and added to the object's custom header to facilitate integrity verification.
Notes
If you have previously added a hash rule to your bucket via the COS console, you can view the hash function you created in the SCF console. Do not delete the function. Otherwise, your rule may not take effect.
Hash calculation is supported in SCF-enabled regions, including Guangzhou, Shanghai, Beijing, Chengdu, Hong Kong (China), Singapore and Silicon Valley. For more supported regions, see the SCF documentation.
If an error is reported during hash calculation, click Log on the right of the function to quickly redirect to the SCF console to view the error logs.
Hash calculation is not supported for files stored in the ARCHIVE or DEEP ARCHIVE storage classes. To calculate the hashes of these files, you need to restore them first. For detailed directions, see Restoring Archived Objects.
The hash calculation feature depends on the SCF service, which provides users with a free tier. You will be billed for the part exceeding the free tier according to SCF pricing.
Directions
1. Log in to the COS console.
2. On the left sidebar, click App Integration > Extended Features and find File Hash Calculation.
3. Click Configure Hash Rule to enter the rule configuration page.
Note: 
 If you haven't activated SCF, go to the SCF console to activate it and authorize the service as instructed.
4. Click Add Function and configure the following parameters:
Function Name: Uniquely identifies a function and cannot be modified after being set. You can view the function in the SCF console.
Associated Bucket: Identifies the COS bucket where the file whose hash is to be calculated resides.
Event Type: An operation that triggers SCF. Take upload as an example. You can initiate an upload by calling the PUT Object or POST Object API. If you choose Create using PUT method as the event type, hash calculation will be triggered only for files uploaded via the PUT Object API.
Trigger Condition: The upload path that will trigger SCF. If you select Specified Range, SCF will be triggered only when a file is uploaded to a path with the specified prefix or suffix. If you select The whole bucket, SCF will be triggered as long as a file is uploaded to any location of the bucket.
SCF Authorization: To enable hash calculation, you need to select this item to authorize SCF to read the corresponding file from your bucket and add the calculated hash to the custom header of the file.
5. Click Confirm.
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You can perform the following operations on the created function:
Click Log to view the historical running status of the hash function. If an error is reported, you can click Log to quickly redirect to the SCF console to view the error log details.
Click More > Edit to modify the hash calculation rule.
Click More > Delete to delete an unwanted hash function.