Generic Request Pre-signing

[rittneje]

The Question

We need to create a pre-signed URL for STS GetCallerIdentity. We are able to do so easily with both the Golang SDK and Python (botocore). However, in the .NET SDK, we can only find pre-signing functionality specific to S3. Is generic pre-signing functionality missing?

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This is a ❓ general question

[ashishdhingra]

Hi @rittneje,

Good morning.

Thanks for posting guidance question. Yes, you are correct. Looking at https://github.com/aws/aws-sdk-net/tree/master/sdk/src/Services/SecurityToken, looks like create pre-signed URL for STS GetCallerIdentity is missing in .NET SDK. The Ruby Presigner version uses the custom implementation, refer https://github.com/aws/aws-sdk-ruby/blob/version-3/gems/aws-sdk-core/lib/aws-sdk-sts/presigner.rb). As a workaround, you may take some guidance from Ruby version and implement your helper method to generate presigned URL.

Hope this helps.

Thanks,
Ashish

[rittneje]

Does the .NET SDK expose Sigv4 itself? The Ruby code you linked references Aws::Sigv4::Signer. The Java, Python, and Golang SDKs also allow public access to it. I would prefer not to have to implement that manually.

[ashishdhingra]

Does the .NET SDK expose Sigv4 itself? The Ruby code you linked references Aws::Sigv4::Signer. The Java, Python, and Golang SDKs also allow public access to it. I would prefer not to have to implement that manually.

@rittneje Please refer https://github.com/aws/aws-sdk-net/blob/master/sdk/src/Core/Amazon.Runtime/Internal/Auth/AWS4Signer.cs for SigV4 signing.

[rittneje]

Thanks. Are we allowed to import that given that it is an "Internal" namespace? Or should we copy-paste the code?

[ashishdhingra]

Thanks. Are we allowed to import that given that it is an "Internal" namespace? Or should we copy-paste the code?

@rittneje The SDK code is organized into various namespaces, Amazon.Runtime.Internal.Auth being one of them. The AWS4Signer is used to sign all the requests before making service API call. You may import the namespace and use AWS4Signer class. For S3, refer AmazonS3Client.GetPreSignedURL() extension.

[rittneje]

Okay. That namespace does not show up in the docs though, so I wasn't sure. https://docs.aws.amazon.com/sdkfornet/v3/apidocs/index.html