Signature calculated for AWSV4 multipart/form-data wrong

[a053a]

Describe the bug
Incorrect signature calculated when signing a request with AWS Signature with form-data parameters.

To Reproduce
Pre-requistes:
Create a REST API Gateway in AWS.
Create a route using AWS_IAM authentication.
Deploy the route.
Create an Access Key for your AWS account so you can sign with the AccessKey and SecretKey.

Steps to reproduce the behavior:

1. Go to Postman
2. Click on POST
3. Enter the URL e.g. https://yourgateway.execute-api.us-east-1.amazonaws.com/deploy/testing
4. Click on Authorization. Choose AWS Signature.
5. Select Add authorization data to Request Headers.
6. Enter your Access Key and Secret Key. Enter Service Name as execute-api.
7. Click on Body. Enter a key and value, it can be anything.
8. Click Send.

Expected behavior
A successful response.

App information (please complete the following information):

• App Type [NativeApp]
• Postman Version [Version 7.32.0 (7.32.0)]
• OS: [e.g. macOS Catalina 10.15.5 (19F101)]

Additional context
This works correctly using my C# POC.
Install AwsSignatureVersion4 nuget package.

[a053a]

Related:

• Incorrect AWS signature for multipart/form-data #8180
• AWS Authentication: The request signature we calculated does not match the signature you provided #5873
• AWS Signature authentication issue old vs new postman versions #4186

[coditva]

Thanks for writing in!
This seems to be a duplicate of #8180

We'll track this in a single thread and ask you to add your observations to that thread itself.
Any updates will be posted there as well. Closing this ticket.