# File lib/mixlib/authentication/signatureverification.rb, line 78
      def authenticate_request(user_secret, time_skew=(15*60))
        Mixlib::Authentication::Log.debug "Initializing header auth : #{request.inspect}"

        @user_secret       = user_secret
        @allowed_time_skew = time_skew # in seconds

        begin
          @auth_request
          
          #BUGBUG Not doing anything with the signing description yet [cb]          
          parse_signing_description

          verify_signature
          verify_timestamp
          verify_content_hash

        rescue StandardError=>se
          raise AuthenticationError,"Failed to authenticate user request. Check your client key and clock: #{se.message}", se.backtrace
        end

        if valid_request?
          SignatureResponse.new(user_id)
        else
          nil
        end
      end