# File lib/fog/aws/signaturev4.rb, line 8
      def initialize(aws_access_key_id, secret_key, region, service)
        @region = region
        @service = service
        @aws_access_key_id  = aws_access_key_id
        @hmac = Fog::HMAC.new('sha256', 'AWS4' + secret_key)
      end