Read Postman AWS signature details in golang

Question

I am passing my AWS access key and secret using the Authorization > AWS Signature section in postman.

I am handling the request using a Golang project.

Now, I am getting the request under this variable : r *http.Request I tried getting different values with r.Header.Get() and facing 2 particular issues:

1. I am not able to get the value of secret
2. I am getting the value of region and access_key using r.Header.Get("Authorization") but its in between a long string. How can I extract them properly ?

I want to