class Aws::Signers::S3

def string_to_sign(request)


CanonicalizedAmzHeaders + CanonicalizedResource;
date ` "\n" `
content-type ` "\n" `
content-md5 ` "\n" `
HTTP-Verb ` "\n" `
StringToSign =

From the S3 developer guide: 
def string_to_sign(request)
  [
    request.http_method,
    request.headers.values_at('Content-Md5', 'Content-Type').join("\n"),
    signing_string_date(request),
    canonicalized_headers(request),
    canonicalized_resource(request.endpoint),
  ].flatten.compact.join("\n")
end