public function verifySignature ( $consumer_secret, $token_secret, $token_type = 'access' )
	{
		$required = array(
						'oauth_consumer_key',
						'oauth_signature_method',
						'oauth_timestamp',
						'oauth_nonce',
						'oauth_signature'
					);

		if ($token_type !== false)
		{
			$required[] = 'oauth_token';
		}

		foreach ($required as $req)
		{
			if (!isset($this->param[$req]))
			{
				throw new OAuthException2('Can\'t verify request signature, missing parameter "'.$req.'"');
			}
		}

		$this->checks();

		$base = $this->signatureBaseString();
		$this->verifyDataSignature($base, $consumer_secret, $token_secret, $this->param['oauth_signature_method'], $this->param['oauth_signature']);
	}