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diff --git a/lib/prado/framework/Web/UI/WebControls/TCaptcha.php b/lib/prado/framework/Web/UI/WebControls/TCaptcha.php
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+<?php
+/**
+ * TCaptcha class file
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @link https://github.com/pradosoft/prado
+ * @copyright Copyright &copy; 2005-2015 The PRADO Group
+ * @license https://github.com/pradosoft/prado/blob/master/COPYRIGHT
+ * @package System.Web.UI.WebControls
+ */
+
+Prado::using('System.Web.UI.WebControls.TImage');
+
+/**
+ * TCaptcha class.
+ *
+ * Notice: while this class is easy to use and implement, it does not provide full security.
+ * In fact, it's easy to bypass the checks reusing old, already-validated tokens (reply attack).
+ * A better alternative is provided by {@link TReCaptcha}.
+ *
+ * TCaptcha displays a CAPTCHA (a token displayed as an image) that can be used
+ * to determine if the input is entered by a real user instead of some program.
+ *
+ * Unlike other CAPTCHA scripts, TCaptcha does not need session or cookie.
+ *
+ * The token (a string consisting of alphanumeric characters) displayed is automatically
+ * generated and can be configured in several ways. To specify the length of characters
+ * in the token, set {@link setMinTokenLength MinTokenLength} and {@link setMaxTokenLength MaxTokenLength}.
+ * To use case-insensitive comparison and generate upper-case-only token, set {@link setCaseSensitive CaseSensitive}
+ * to false. Advanced users can try to set {@link setTokenAlphabet TokenAlphabet}, which
+ * specifies what characters can appear in tokens.
+ *
+ * The validation of the token is related with two properties: {@link setTestLimit TestLimit}
+ * and {@link setTokenExpiry TokenExpiry}. The former specifies how many times a token can
+ * be tested with on the server side, and the latter says when a generated token will expire.
+ *
+ * To specify the appearance of the generated token image, set {@link setTokenImageTheme TokenImageTheme}
+ * to be an integer between 0 and 63. And to adjust the generated image size, set {@link setTokenFontSize TokenFontSize}
+ * (you may also set {@link TWebControl::setWidth Width}, but the scaled image may not look good.)
+ * By setting {@link setChangingTokenBackground ChangingTokenBackground} to true, the image background
+ * of the token will be variating even though the token is the same during postbacks.
+ *
+ * Upon postback, user input can be validated by calling {@link validate()}.
+ * The {@link TCaptchaValidator} control can also be used to do validation, which provides
+ * client-side validation besides the server-side validation.  By default, the token will
+ * remain the same during multiple postbacks. A new one can be generated by calling
+ * {@link regenerateToken()} manually.
+ *
+ * The following template shows a typical use of TCaptcha control:
+ * <code>
+ * <com:TCaptcha ID="Captcha" />
+ * <com:TTextBox ID="Input" />
+ * <com:TCaptchaValidator CaptchaControl="Captcha"
+ *                        ControlToValidate="Input"
+ *                        ErrorMessage="You are challenged!" />
+ * </code>
+ *
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @package System.Web.UI.WebControls
+ * @since 3.1.1
+ */
+class TCaptcha extends TImage
+{
+	const MIN_TOKEN_LENGTH=2;
+	const MAX_TOKEN_LENGTH=40;
+	private $_privateKey;
+	private $_validated=false;
+
+	/**
+	 * @return integer the theme of the token image. Defaults to 0.
+	 */
+	public function getTokenImageTheme()
+	{
+		return $this->getViewState('TokenImageTheme',0);
+	}
+
+	/**
+	 * Sets the theme of the token image.
+	 * You may test each theme to find out the one you like the most.
+	 * Below is the explanation of the theme value:
+	 * It is treated as a 5-bit integer. Each bit toggles a specific feature of the image.
+	 * Bit 0 (the least significant): whether the image is opaque (1) or transparent (0).
+	 * Bit 1: whether we should add white noise to the image (1) or not (0).
+	 * Bit 2: whether we should add a grid to  the image (1) or not (0).
+	 * Bit 3: whether we should add some scribbles to the image (1) or not (0).
+	 * Bit 4: whether the image background should be morphed (1) or not (0).
+	 * Bit 5: whether the token text should cast a shadow (1) or not (0).
+	 * @param integer the theme of the token image. It must be an integer between 0 and 63.
+	 */
+	public function setTokenImageTheme($value)
+	{
+		$value=TPropertyValue::ensureInteger($value);
+		if($value>=0 && $value<=63)
+			$this->setViewState('TokenImageTheme',$value,0);
+		else
+			throw new TConfigurationException('captcha_tokenimagetheme_invalid',0,63);
+	}
+
+	/**
+	 * @return integer the font size used for displaying the token in an image. Defaults to 30.
+	 */
+	public function getTokenFontSize()
+	{
+		return $this->getViewState('TokenFontSize',30);
+	}
+
+	/**
+	 * Sets the font size used for displaying the token in an image.
+	 * This property affects the generated token image size.
+	 * The image width is proportional to this font size.
+	 * @param integer the font size used for displaying the token in an image. It must be an integer between 20 and 100.
+	 */
+	public function setTokenFontSize($value)
+	{
+		$value=TPropertyValue::ensureInteger($value);
+		if($value>=20 && $value<=100)
+			$this->setViewState('TokenFontSize',$value,30);
+		else
+			throw new TConfigurationException('captcha_tokenfontsize_invalid',20,100);
+	}
+
+	/**
+	 * @return integer the minimum length of the token. Defaults to 4.
+	 */
+	public function getMinTokenLength()
+	{
+		return $this->getViewState('MinTokenLength',4);
+	}
+
+	/**
+	 * @param integer the minimum length of the token. It must be between 2 and 40.
+	 */
+	public function setMinTokenLength($value)
+	{
+		$length=TPropertyValue::ensureInteger($value);
+		if($length>=self::MIN_TOKEN_LENGTH && $length<=self::MAX_TOKEN_LENGTH)
+			$this->setViewState('MinTokenLength',$length,4);
+		else
+			throw new TConfigurationException('captcha_mintokenlength_invalid',self::MIN_TOKEN_LENGTH,self::MAX_TOKEN_LENGTH);
+	}
+
+	/**
+	 * @return integer the maximum length of the token. Defaults to 6.
+	 */
+	public function getMaxTokenLength()
+	{
+		return $this->getViewState('MaxTokenLength',6);
+	}
+
+	/**
+	 * @param integer the maximum length of the token. It must be between 2 and 40.
+	 */
+	public function setMaxTokenLength($value)
+	{
+		$length=TPropertyValue::ensureInteger($value);
+		if($length>=self::MIN_TOKEN_LENGTH && $length<=self::MAX_TOKEN_LENGTH)
+			$this->setViewState('MaxTokenLength',$length,6);
+		else
+			throw new TConfigurationException('captcha_maxtokenlength_invalid',self::MIN_TOKEN_LENGTH,self::MAX_TOKEN_LENGTH);
+	}
+
+	/**
+	 * @return boolean whether the token should be treated as case-sensitive. Defaults to true.
+	 */
+	public function getCaseSensitive()
+	{
+		return $this->getViewState('CaseSensitive',true);
+	}
+
+	/**
+	 * @param boolean whether the token should be treated as case-sensitive. If false, only upper-case letters will appear in the token.
+	 */
+	public function setCaseSensitive($value)
+	{
+		$this->setViewState('CaseSensitive',TPropertyValue::ensureBoolean($value),true);
+	}
+
+	/**
+	 * @return string the characters that may appear in the token. Defaults to '234578adefhijmnrtABDEFGHJLMNRT'.
+	 */
+	public function getTokenAlphabet()
+	{
+		return $this->getViewState('TokenAlphabet','234578adefhijmnrtABDEFGHJLMNRT');
+	}
+
+	/**
+	 * @param string the characters that may appear in the token. At least 2 characters must be specified.
+	 */
+	public function setTokenAlphabet($value)
+	{
+		if(strlen($value)<2)
+			throw new TConfigurationException('captcha_tokenalphabet_invalid');
+		$this->setViewState('TokenAlphabet',$value,'234578adefhijmnrtABDEFGHJLMNRT');
+	}
+
+	/**
+	 * @return integer the number of seconds that a generated token will remain valid. Defaults to 600 seconds (10 minutes).
+	 */
+	public function getTokenExpiry()
+	{
+		return $this->getViewState('TokenExpiry',600);
+	}
+
+	/**
+	 * @param integer the number of seconds that a generated token will remain valid. A value smaller than 1 means the token will not expire.
+	 */
+	public function setTokenExpiry($value)
+	{
+		$this->setViewState('TokenExpiry',TPropertyValue::ensureInteger($value),600);
+	}
+
+	/**
+	 * @return boolean whether the background of the token image should be variated during postbacks. Defaults to false.
+	 */
+	public function getChangingTokenBackground()
+	{
+		return $this->getViewState('ChangingTokenBackground',false);
+	}
+
+	/**
+	 * @param boolean whether the background of the token image should be variated during postbacks.
+	 */
+	public function setChangingTokenBackground($value)
+	{
+		$this->setViewState('ChangingTokenBackground',TPropertyValue::ensureBoolean($value),false);
+	}
+
+	/**
+	 * @return integer how many times a generated token can be tested. Defaults to 5.
+	 */
+	public function getTestLimit()
+	{
+		return $this->getViewState('TestLimit',5);
+	}
+
+	/**
+	 * @param integer how many times a generated token can be tested. For unlimited tests, set it to 0.
+	 */
+	public function setTestLimit($value)
+	{
+		$this->setViewState('TestLimit',TPropertyValue::ensureInteger($value),5);
+	}
+
+	/**
+	 * @return boolean whether the currently generated token has expired.
+	 */
+	public function getIsTokenExpired()
+	{
+		if(($expiry=$this->getTokenExpiry())>0 && ($start=$this->getViewState('TokenGenerated',0))>0)
+			return $expiry+$start<time();
+		else
+			return false;
+	}
+
+	/**
+	 * @return string the public key used for generating the token. A random one will be generated and returned if this is not set.
+	 */
+	public function getPublicKey()
+	{
+		if(($publicKey=$this->getViewState('PublicKey',''))==='')
+		{
+			$publicKey=$this->generateRandomKey();
+			$this->setPublicKey($publicKey);
+		}
+		return $publicKey;
+	}
+
+	/**
+	 * @param string the public key used for generating the token. A random one will be generated if this is not set.
+	 */
+	public function setPublicKey($value)
+	{
+		$this->setViewState('PublicKey',$value,'');
+	}
+
+	/**
+	 * @return string the token that will be displayed
+	 */
+	public function getToken()
+	{
+		return $this->generateToken($this->getPublicKey(),$this->getPrivateKey(),$this->getTokenAlphabet(),$this->getTokenLength(),$this->getCaseSensitive());
+	}
+
+	/**
+	 * @return integer the length of the token to be generated.
+	 */
+	protected function getTokenLength()
+	{
+		if(($tokenLength=$this->getViewState('TokenLength'))===null)
+		{
+			$minLength=$this->getMinTokenLength();
+			$maxLength=$this->getMaxTokenLength();
+			if($minLength>$maxLength)
+				$tokenLength=rand($maxLength,$minLength);
+			else if($minLength<$maxLength)
+				$tokenLength=rand($minLength,$maxLength);
+			else
+				$tokenLength=$minLength;
+			$this->setViewState('TokenLength',$tokenLength);
+		}
+		return $tokenLength;
+	}
+
+	/**
+	 * @return string the private key used for generating the token. This is randomly generated and kept in a file for persistency.
+	 */
+	public function getPrivateKey()
+	{
+		if($this->_privateKey===null)
+		{
+			$fileName=$this->generatePrivateKeyFile();
+			$content=file_get_contents($fileName);
+			$matches=array();
+			if(preg_match("/privateKey='(.*?)'/ms",$content,$matches)>0)
+				$this->_privateKey=$matches[1];
+			else
+				throw new TConfigurationException('captcha_privatekey_unknown');
+		}
+		return $this->_privateKey;
+	}
+
+	/**
+	 * Validates a user input with the token.
+	 * @param string user input
+	 * @return boolean if the user input is not the same as the token.
+	 */
+	public function validate($input)
+	{
+		$number=$this->getViewState('TestNumber',0);
+		if(!$this->_validated)
+		{
+			$this->setViewState('TestNumber',++$number);
+			$this->_validated=true;
+		}
+		if($this->getIsTokenExpired() || (($limit=$this->getTestLimit())>0 && $number>$limit))
+		{
+			$this->regenerateToken();
+			return false;
+		}
+		return ($this->getToken()===($this->getCaseSensitive()?$input:strtoupper($input)));
+	}
+
+	/**
+	 * Regenerates the token to be displayed.
+	 * By default, a token, once generated, will remain the same during the following page postbacks.
+	 * Calling this method will generate a new token.
+	 */
+	public function regenerateToken()
+	{
+		$this->clearViewState('TokenLength');
+		$this->setPublicKey('');
+		$this->clearViewState('TokenGenerated');
+		$this->clearViewState('RandomSeed');
+		$this->clearViewState('TestNumber',0);
+	}
+
+	/**
+	 * Configures the image URL that shows the token.
+	 * @param mixed event parameter
+	 */
+	public function onPreRender($param)
+	{
+		parent::onPreRender($param);
+		if(!self::checkRequirements())
+			throw new TConfigurationException('captcha_imagettftext_required');
+		if(!$this->getViewState('TokenGenerated',0))
+		{
+			$manager=$this->getApplication()->getAssetManager();
+			$manager->publishFilePath($this->getFontFile());
+			$url=$manager->publishFilePath($this->getCaptchaScriptFile());
+			$url.='?options='.urlencode($this->getTokenImageOptions());
+			$this->setImageUrl($url);
+
+			$this->setViewState('TokenGenerated',time());
+		}
+	}
+
+	/**
+	 * @return string the options to be passed to the token image generator
+	 */
+	protected function getTokenImageOptions()
+	{
+		$privateKey=$this->getPrivateKey();  // call this method to ensure private key is generated
+		$token=$this->getToken();
+		$options=array();
+		$options['publicKey']=$this->getPublicKey();
+		$options['tokenLength']=strlen($token);
+		$options['caseSensitive']=$this->getCaseSensitive();
+		$options['alphabet']=$this->getTokenAlphabet();
+		$options['fontSize']=$this->getTokenFontSize();
+		$options['theme']=$this->getTokenImageTheme();
+		if(($randomSeed=$this->getViewState('RandomSeed',0))===0)
+		{
+			$randomSeed=(int)(microtime()*1000000);
+			$this->setViewState('RandomSeed',$randomSeed);
+		}
+		$options['randomSeed']=$this->getChangingTokenBackground()?0:$randomSeed;
+		$str=serialize($options);
+		return base64_encode(md5($privateKey.$str).$str);
+	}
+
+	/**
+	 * @return string the file path of the PHP script generating the token image
+	 */
+	protected function getCaptchaScriptFile()
+	{
+		return dirname(__FILE__).DIRECTORY_SEPARATOR.'assets'.DIRECTORY_SEPARATOR.'captcha.php';
+	}
+
+	protected function getFontFile()
+	{
+		return dirname(__FILE__).DIRECTORY_SEPARATOR.'assets'.DIRECTORY_SEPARATOR.'verase.ttf';
+	}
+
+	/**
+	 * Generates a file with a randomly generated private key.
+	 * @return string the path of the file keeping the private key
+	 */
+	protected function generatePrivateKeyFile()
+	{
+		$captchaScript=$this->getCaptchaScriptFile();
+		$path=dirname($this->getApplication()->getAssetManager()->getPublishedPath($captchaScript));
+		$fileName=$path.DIRECTORY_SEPARATOR.'captcha_key.php';
+		if(!is_file($fileName))
+		{
+			@mkdir($path);
+			$key=$this->generateRandomKey();
+			$content="<?php
+\$privateKey='$key';
+?>";
+			file_put_contents($fileName,$content);
+		}
+		return $fileName;
+	}
+
+	/**
+	 * @return string a randomly generated key
+	 */
+	protected function generateRandomKey()
+	{
+		return md5(rand().rand().rand().rand());
+	}
+
+	/**
+	 * Generates the token.
+	 * @param string public key
+	 * @param string private key
+	 * @param integer the length of the token
+	 * @param boolean whether the token is case sensitive
+	 * @return string the token generated.
+	 */
+	protected function generateToken($publicKey,$privateKey,$alphabet,$tokenLength,$caseSensitive)
+	{
+		$token=substr($this->hash2string(md5($publicKey.$privateKey),$alphabet).$this->hash2string(md5($privateKey.$publicKey),$alphabet),0,$tokenLength);
+		return $caseSensitive?$token:strtoupper($token);
+	}
+
+	/**
+	 * Converts a hash string into a string with characters consisting of alphanumeric characters.
+	 * @param string the hexadecimal representation of the hash string
+	 * @param string the alphabet used to represent the converted string. If empty, it means '234578adefhijmnrtwyABDEFGHIJLMNQRTWY', which excludes those confusing characters.
+	 * @return string the converted string
+	 */
+	protected function hash2string($hex,$alphabet='')
+	{
+		if(strlen($alphabet)<2)
+			$alphabet='234578adefhijmnrtABDEFGHJLMNQRT';
+		$hexLength=strlen($hex);
+		$base=strlen($alphabet);
+		$result='';
+		for($i=0;$i<$hexLength;$i+=6)
+		{
+			$number=hexdec(substr($hex,$i,6));
+			while($number)
+			{
+				$result.=$alphabet[$number%$base];
+				$number=floor($number/$base);
+			}
+		}
+		return $result;
+	}
+
+	/**
+	 * Checks the requirements needed for generating CAPTCHA images.
+	 * TCaptach requires GD2 with TrueType font support and PNG image support.
+	 * @return boolean whether the requirements are satisfied.
+	 */
+	public static function checkRequirements()
+	{
+		return extension_loaded('gd') && function_exists('imagettftext') && function_exists('imagepng');
+	}
+}
+