private function getResponse(): ?string
    {
        $HA1 = $this->getHA1();
        $nonce = $this->getNonce();
        $HA2 = $this->getHA2();

        if (null !== $HA1 && ($nonce) && null !== $HA2) {
            $qop = $this->getQOP();

            if (empty($qop)) {
                $response = $this->hash("{$HA1}:{$nonce}:{$HA2}");

                return $response;
            }

            $cnonce = $this->getClientNonce();
            $nc = $this->getNonceCount();
            if (($cnonce) && ($nc)) {
                $response = $this->hash("{$HA1}:{$nonce}:{$nc}:{$cnonce}:{$qop}:{$HA2}");

                return $response;
            }
        }

        return null;
    }
private function getResponse(): ?string
    {
        $HA1 = $this->getHA1();
        $nonce = $this->getNonce();
        $HA2 = $this->getHA2();

        if (null !== $HA1 && ($nonce) && null !== $HA2) {
            $qop = $this->getQOP();

            if (empty($qop)) {
                $response = $this->hash("{$HA1}:{$nonce}:{$HA2}");

                return $response;
            }

            $cnonce = $this->getClientNonce();
            $nc = $this->getNonceCount();
            if (($cnonce) && ($nc)) {
                $response = $this->hash("{$HA1}:{$nonce}:{$nc}:{$cnonce}:{$qop}:{$HA2}");

                return $response;
            }
        }

        return null;
    }
private function getResponse ( ) : ? string { $ HA1 = $ this -> getHA1 ( ) ; $ nonce = $ this -> getNonce ( ) ; $ HA2 = $ this -> getHA2 ( ) ; if ( null !== $ HA1 && ( $ nonce ) && null !== $ HA2 ) { $ qop = $ this -> getQOP ( ) ; if ( empty ( $ qop ) ) { $ response = $ this -> hash ( "{$HA1}:{$nonce}:{$HA2}" ) ; return $ response ; } $ cnonce = $ this -> getClientNonce ( ) ; $ nc = $ this -> getNonceCount ( ) ; if ( ( $ cnonce ) && ( $ nc ) ) { $ response = $ this -> hash ( "{$HA1}:{$nonce}:{$nc}:{$cnonce}:{$qop}:{$HA2}" ) ; return $ response ; } } return null ; }
Calculates the value of response according to RFC 2617 and RFC 2069.

@return string The value of response
Calculates the value of response according to RFC 2617 and RFC 2069 .