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Captcha Adapters

The following adapters are shipped with Zend Framework by default.

Zend_Captcha_Word

Zend_Captcha_Word is an abstract adapter that serves as the basis for the Dumb, Figlet, and Image adapters. It provides mutators for specifying word length, session TTL, the session namespace object to use, and the session namespace class to use for persistence if you do not wish to use Zend_Session_Namespace. Additionally, it encapsulates all validation logic.

By default, the word length is 8 characters, the session timeout is 5 minutes, and Zend_Session_Namespace is used for persistence (using the namespace "Zend_Form_Captcha_<captcha ID>").

In addition to the standard methods required by the Zend_Captcha_Adapter interface, Zend_Captcha_Word exposes the following methods:

  • setWordLen($length) and getWordLen() allow you to specify the length of the generated "word" in characters, and to retrieve the current value.

  • setTimeout($ttl) and getTimeout() allow you to specify the time-to-live of the session token, and to retrieve the current value. $ttl should be specified in seconds.

  • setSessionClass($class) and getSessionClass() allow you to specify an alternate Zend_Session_Namespace implementation to use to persist the captcha token, as well as to retrieve the current value.

  • getId() allows you to retrieve the current token identifier.

  • getWord() allows you to retrieve the generated word to use with the captcha; it will generate it for you if none has been generated yet.

  • setSession(Zend_Session_Namespace $session) allows you to specify a session object to use for persisting the captcha token; getSession() allows you to retrieve the current session object.

All Word captchas allow you to pass an array of options to the constructor, or, alternately, pass them to setOptions() (or pass a Zend_Config object to setConfig()). By default, the wordLen, timeout, and sessionClass keys may all be used; each concrete implementation may define additional keys or utilize the options in other ways.

Note:

Remeber, Word is an abstract class and may not be instantiated directly.

Zend_Captcha_Dumb

The Dumb adapter is mostly self-describing. It provides a random string that needs to be typed in reverse to validate. As such, it's not a good CAPTCHA solution, and should only be used either for testing or as a last resort. It extends Zend_Captcha_Word.

Zend_Captcha_Figlet

The Figlet adapter utilizes Zend_Text_Figlet to present a Figlet to the user. Figlet captchas are limited to characters only.

Options passed to the constructor will also be passed to the Zend_Text_Figlet object the adapter utilizes; see that documentation for details on what configuration options may be utilized.

Zend_Captcha_Image

The Image adapter takes the word generated and renders it as an image, performing various skewing permutations on it to make it difficult to automatically decipher. To perform its work, it requires the » GD extension compiled with TrueType or Freetype support. Currently, the Image adapter can only generate PNG images.

Zend_Captcha_Image extends Zend_Captcha_Word, and additionally exposes the following methods:

  • setExpiration($expiration) and getExpiration() allow you to specify a maximum lifetime a captcha image may reside on the filesystem. This is typically a longer duration than the session lifetime. Garbage collection is run periodically each time the captcha object is invoked, and images that have expired will be cleaned up. Expiration values are in seconds.

  • setGcFreq($gcFreq) and getGcFreg() allow you to specify how frequently garbage collection should run. Garbage collection will run every 1/$gcFreq calls (default is 100).

  • setFont($font) and getFont() allow you to specify the font you wish to utilize. It should be a fully qualified path to the font file to utilize. If you do not set this value, the captcha will throw an exception during generation; the font is mandatory.

  • setFontSize($fsize) and getFontSize() allow you to specify the font size, in pixels, to use when generating the captcha. This defaults to 24px.

  • setHeight($height) and getHeight() allow you to specify the height, in pixels, of the generated captcha image. This defaults to 50px.

  • setWidth($width) and getWidth() allow you to specify the width, in pixels, of the generated captcha image. This defaults to 200px.

  • setImgDir($imgDir) and getImgDir() allow you to specify the directory in which captcha images are stored. This defaults to "./images/captcha/", which should look relative to the bootstrap script.

  • setImgUrl($imgUrl) and getImgUrl() allow you to specify the relative path to a captcha image to use for the HTML markup. This defaults to "/images/captcha/".

  • setSuffix($suffix) and getSuffix() allows you to specify the filename suffix to utilize. This defaults to ".png". Note: changing this will not change the image type generated.

All of the above options may be passed as options to the constructor by simply removing the 'set' method prefix and casting the initial letter to lowercase: "suffix", "height", "imgUrl", etc.

Zend_Captcha_ReCaptcha

The ReCaptcha adapter utilizes Zend_Service_ReCaptcha to generate and validate captchas. It exposes the following methods:

  • setPrivKey($key) and getPrivKey() allow you to specify the private key you use with the ReCaptcha service. This must be specified during construction, though it may be overridden at any point.

  • setPubKey($key) and getPubKey() allow you to specify the public key you use with the ReCaptcha service. This must be specified during construction, though it may be overridden at any point.

  • setService(Zend_Service_ReCaptcha $service) and getService() allow you to specify and interact with the ReCaptcha service object.

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