What is the CRT-V4a signing feature

[scrocquesel]

In the code, there is an exception that can be thrown at runtime: "You must add a dependency on the 'software.amazon.awssdk:http-auth-aws-crt' module to enable the CRT-V4a signing feature" when creating an instance of AwsV4aHttpSigner.

I understand that it is related to the aws.auth#sigv4a auth scheme and used in the DefaultS3Presigner class, but when and how can a user opt-in/opt-out with this auth scheme? In other words, under what circumstances can this exception be thrown?

[debora-ito]

SigV4a is used for multi-region requests. A high-level explanation can be found in the S3 Multi-Region Access Points docs -

Multi-Region Access Point requests must be signed by using Signature Version 4A (SigV4A). When you use the AWS SDKs, the SDK automatically converts a SigV4 to SigV4A. Therefore, make sure that your AWS SDK supports SigV4A as the signing implementation that is used to sign the global AWS Region requests. For more information about SigV4A, see Signing AWS API requests in the AWS General Reference.

[scrocquesel]

Any reason why SigV4A is only supported with aws-crt ?

[github-actions[bot]]

Hello! Reopening this discussion to make it searchable.