diff --git a/README.txt b/README.txt
new file mode 100644
index 0000000..49c6dbd
--- /dev/null
+++ b/README.txt
@@ -0,0 +1,50 @@
+CPF Profile Field
+===
+This is a CPF field to user profiles into moodle.
+
+The Cadastro de Pessoas Físicas (CPF) – Portuguese for Natural Persons Register – is a number attributed by the Brazilian revenue agency (Receita Federal – Federal Revenue) to both Brazilians and resident aliens who pay taxes or take part, directly or indirectly, in activities that provide revenue for any of the dozens of different types of taxes existing in Brazil.
+
+More about CPF: http://en.wikipedia.org/wiki/Cadastro_de_Pessoas_F%C3%ADsicas
+
+For Everyone
+---
+This plugin was made to add possibility to add CPF field in the user profile form.
+
+Moodle documentation about profilefields -> http://docs.moodle.org/26/en/User_profile_fields
+
+I recommend to insert a mask plugin to the CPF field. I did as follows:
+
+- Added the Jquery masked Input plugin -> http://digitalbush.com/projects/masked-input-plugin/
+- Added the follow code relative to the masked field into the selected theme file:
+> jQuery("#profilefield_cpf").mask("999.999.999-99");
+
+Para Brasileiros
+---
+Como CPF é um padrão brasileiro, a explicação será em português. :)
+Este plugin foi criado para possibilitar a inclusão do campo cpf nos formulários de criação de novos usuários e também na alteração dos dados do usuário.
+
+Documentação de como utilizar os profilefields -> http://docs.moodle.org/26/en/User_profile_fields
+
+Recomendo inserir um plugin de máscara para o campo CPF. Eu fiz da seguinte forma:
+- Adicionei o plugin Jquery masked Input -> http://digitalbush.com/projects/masked-input-plugin/
+- Adicionei o seguinte código referente à mascara do campo no tema utilizado:
+> jQuery("#profilefield_cpf").mask("999.999.999-99");
+
+Installation
+---
+
+As usual:
+
+* Download the source code (zip or git clone)
+* Uncompress to user/profile/field/cpf
+* Go to **Notifications**
+
+License
+---
+
+It is released as GPL v3.
+
+Authors:
+* Willian Mano - http://willianmano.net
+
+Copyright 2014 onwards Willian Mano (http://willianmano.net)
\ No newline at end of file
diff --git a/define.class.php b/define.class.php
index b7a89c1..3eda317 100644
--- a/define.class.php
+++ b/define.class.php
@@ -1,14 +1,19 @@
 <?php
 
 class profile_define_cpf extends profile_define_base {
-
-    function define_form_specific($form) {
-        /// Default data
-        $form->addElement('text', 'defaultdata', get_string('profiledefaultdata', 'admin'), 'size="50"');
-        $form->setType('defaultdata', PARAM_TEXT);
-
+    public function define_form_specific($form) {
+        // Default data.
+        $form->addElement('text', 'defaultdata', 'Informe o CPF');
+		$form->setType('defaultdata', PARAM_TEXT);
+        $form->setDefault('defaultdata', '(somente dígitos)')
     }
 
+   function define_validate_specific($data) {
+     $errors = array();
+     // Make sure defaultdata is not false
+     if ($data->defaultdata == false) {
+       $errors['cpf'] = 'Obrigatório'; //get_string('noprovided', 'profilefield_cpf');
+     }
+     return $errors;
+   }
 }
-
-
diff --git a/field.class.php b/field.class.php
index d1e4056..bbc7e7c 100644
--- a/field.class.php
+++ b/field.class.php
@@ -1,57 +1,117 @@
 <?php
 
 class profile_field_cpf extends profile_field_base {
-    /**
-     * Overwrite the base class to display the data for this field
-     */
-    function display_data() {
-        /// Default formatting
-        $data = parent::display_data();
-        $data = str_pad($data, 11, '0', STR_PAD_LEFT); // Prevent low digits formatting errors
-        if ($data !== '') {
-            $data = substr($data,0,3).'.'.substr($data,3,3).'.'.substr($data,6,3).'-'.substr($data,9,2);
+    public function edit_field_add($mform) {
+        $mform->addElement(
+            'text',
+            $this->inputname,
+            format_string($this->field->name),
+            'maxlength="11" size="11" id="profilefield_cpf" pattern="[0-9]{11}" data-tip="Informe o CPF (apenas números)" title="Apenas números"'
+        );
+        $mform->setType($this->inputname, PARAM_TEXT);
+//	if ($this->is_required() and !has_capability('moodle/user:update', get_context_instance(CONTEXT_SYSTEM))) {
+//	       $mform->addRule($this->inputname, get_string('regexerrormessage', 'pluginname'), 'regex', '\d{11}');
+               $mform->addRule($this->inputname, get_string('onlydigits', 'profilefield_cpf'), 'numeric', null, 'client');
+//get_string('required'), 'nonzero', null, 'client');
+//	   }
+    }
+    
+    public function edit_validate_field($usernew) {
+        $return = array();
+        if (isset($usernew->{$this->inputname})) {
+            if (!$this->exists($usernew->{$this->inputname}, $usernew->id)) {
+                $return[$this->inputname] = get_string('cpfexists', 'profilefield_cpf');
+            } else if (!$this->validatecpf($usernew->{$this->inputname})) {
+                $return[$this->inputname] = get_string('invalidcpf', 'profilefield_cpf');
+            }
         }
-        return $data;
+        return $return;
     }
 
-    function edit_field_add($mform) {
-        /// Create the form field
-        $mform->addElement('text', $this->inputname, format_string($this->field->name), 'maxlength="11" size="11"');
-        $mform->setType($this->inputname, PARAM_TEXT);
+   // Define formatação para o campo de CPF
+   public function display_data() {
+	if( preg_match( "/^(\d{3})(\d{3})(\d{3})(\d{2})$/", $this->data,  $matches ) )  { 
+         	$result = $matches[1] . '.' .$matches[2] . '.' . $matches[3] . '-' . $matches[4];
+	} else {
+		$result = $this->data;
+	}
+	return $result;
+   }
+
+
+    /*
+	Testa se já existe algum usuário com este mesmo número de CPF.
+        Se existir, retorna falso, do contrário retorna verdadeiro.
+    */
+    private function exists($cpf = null, $userid = 0) {
+	global $DB;
+
+    	// Por definição, se for admin, aceita 00000000000
+    	if( is_siteadmin() && $cpf == '00000000000') {
+    	    return true;
+    	}
+    	                             	    
+            // Verifica se um número foi informado.
+            if (is_null($cpf)) {
+                return false;
+    	}
+
+            $sql = "SELECT uid.data FROM {user_info_data} uid
+    		INNER JOIN {user_info_field} uif ON uid.fieldid = uif.id
+                    INNER JOIN {user} u on uid.userid = u.id
+                    WHERE uif.datatype = 'cpf' AND u.deleted = 0 AND uid.data = :cpf AND uid.userid <> :userid";
+            $params['cpf'] = $cpf;
+            $params['userid'] = $userid;
+            $dbcpf = current($DB->get_records_sql($sql, $params));
+
+            if (!empty($dbcpf)) {
+                return false;
+            } else {
+                return true;
+            }
     }
 
-    function edit_validate_field($usernew) {
-        // Get default validation errors
-        $errors = parent::edit_validate_field($usernew);
-        if ($errors) {
-            return $errors;
+    /*
+	Verifica se um determinado valor passado corresponde a um número de CPF válido
+        Retorna verdadeiro apenas se DV bater com esperado 
+    */
+    private function validatecpf($cpf = null) {
+        // Por definição, se for admin, aceita 00000000000
+	if( is_siteadmin() && $cpf == '00000000000') {
+	    return true;    
+	}
+       
+       // Verifica se um numero foi informado.
+        if (is_null($cpf)) {
+            return false;
+        }
+        if (!is_numeric($cpf)) {
+            return false;
         }
+        //$cpf = str_pad($cpf, 11, '0', STR_PAD_LEFT);
 
-        // Based on script by Moacir, in http://codigofonte.uol.com.br/codigos/validacao-de-cpf-com-php
-        if (isset($usernew->{$this->inputname})) {
-            $cpf = $usernew->{$this->inputname};
-            if (!ctype_digit($cpf)) {
-                return array($this->inputname => get_string('cpf_digits', 'profilefield_cpf'));
-            }
-            if (strlen($cpf) != 11) {
-                return array($this->inputname => get_string('cpf_size', 'profilefield_cpf'));
-            }
-            if (in_array($cpf, array('00000000000', '11111111111', '22222222222', '33333333333', '44444444444', '55555555555', '66666666666', '77777777777', '88888888888', '99999999999'))) {
-                return array($this->inputname => get_string('cpf_invalid', 'profilefield_cpf'));
-            }
+        // Verifica se o numero de digitos informados eh igual a 11.
+        if (strlen($cpf) != 11) {
+            return false;
+        } else if ($cpf == '00000000000' || $cpf == '11111111111' || $cpf == '22222222222' ||
+            $cpf == '33333333333' || $cpf == '44444444444' || $cpf == '55555555555' ||
+            $cpf == '66666666666' || $cpf == '77777777777' || $cpf == '88888888888' ||
+            $cpf == '99999999999') {
+            return false;
+        } else {
+            // Calcula os digitos verificadores para verificar se o CPF eh valido.
             for ($t = 9; $t < 11; $t++) {
+
                 for ($d = 0, $c = 0; $c < $t; $c++) {
-                    $v = substr($cpf,$c,1);
-                    $d += $v * (($t + 1) - $c);
+                    $d += $cpf{$c} * (($t + 1) - $c);
                 }
-                $v = substr($cpf,$c,1);
                 $d = ((10 * $d) % 11) % 10;
-                if ($v != $d) {
-                    return array($this->inputname => get_string('cpf_invalid', 'profilefield_cpf'));
+                if ($cpf{$c} != $d) {
+                    return false;
                 }
             }
+
+            return true;
         }
-        return $errors;
     }
-
 }
diff --git a/lang/en/profilefield_cpf.php b/lang/en/profilefield_cpf.php
index 73853af..0855157 100644
--- a/lang/en/profilefield_cpf.php
+++ b/lang/en/profilefield_cpf.php
@@ -16,14 +16,14 @@
 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
 
 /**
- * Strings for component 'profilefield_text', language 'en', branch 'MOODLE_20_STABLE'
+ * Strings for component 'cpf_text', language 'en'
  *
- * @package   profilefield_text
- * @copyright 1999 onwards Martin Dougiamas  {@link http://moodle.com}
+ * @package   cpf_text
+ * @copyright 2014 onwards Willian Mano  {@link http://willianmano.net}
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 
-$string['pluginname'] = 'Brazilian CPF';
-$string['cpf_digits'] = 'CPF must have only numeric digits';
-$string['cpf_size'] = 'CPF must have 11 digits';
-$string['cpf_invalid'] = 'Invalid CPF';
+$string['pluginname'] = 'CPF input';
+$string['invalidcpf'] = 'Invalid CPF';
+$string['cpfexists'] = 'CPF already exists';
+$string['onlydigits'] = 'Only digits are accepted';
diff --git a/lang/pt_br/profilefield_cpf.php b/lang/pt_br/profilefield_cpf.php
index 230ab4f..a5da93e 100644
--- a/lang/pt_br/profilefield_cpf.php
+++ b/lang/pt_br/profilefield_cpf.php
@@ -16,14 +16,15 @@
 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
 
 /**
- * Strings for component 'profilefield_text', language 'en', branch 'MOODLE_20_STABLE'
+ * Strings for component 'cpf_text', language 'pt_br'
  *
- * @package   profilefield_text
- * @copyright 1999 onwards Martin Dougiamas  {@link http://moodle.com}
+ * @package   cpf_text
+ * @copyright 2014 onwards Willian Mano  {@link http://willianmano.net}
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 
-$string['pluginname'] = 'CPF brasileiro';
-$string['cpf_digits'] = 'O CPF deve ser formado apenas por dígitos numéricos';
-$string['cpf_size'] = 'O CPF deve ter exatos 11 dígitos';
-$string['cpf_invalid'] = 'CPF inválido';
+$string['pluginname'] = 'Campo de CPF';
+$string['invalidcpf'] = 'CPF inválido';
+$string['cpfexists'] = 'CPF já existe';
+$string['onlydigits'] = 'Informe apenas dígitos';
+$string['required'] = 'É obrigatório informar o CPF';
diff --git a/version.php b/version.php
index d1288b2..7baa199 100644
--- a/version.php
+++ b/version.php
@@ -15,14 +15,15 @@
 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
 
 /**
- * @package    profilefield
- * @subpackage text
- * @copyright  2007 onwards Shane Elliot {@link http://pukunui.com}
+ * @package    cpf
+ * @copyright  2014 onwards Willian Mano {@link http://willianmano.net}
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 
 defined('MOODLE_INTERNAL') || die();
 
-$plugin->version   = 2013050100;        // The current plugin version (Date: YYYYMMDDXX)
-$plugin->requires  = 2013050100;        // Requires this Moodle version
-$plugin->component = 'profilefield_cpf'; // Full name of the plugin (used for diagnostics)
+$plugin->version   = 2017051702;        // The current plugin version (Date: YYYYMMDDXX).
+$plugin->requires  = 2012062500;        // Requires this Moodle version.
+$plugin->maturity = MATURITY_STABLE;
+$plugin->release  = 'Version for Moodle 2.2 onwards';
+$plugin->component = 'profilefield_cpf';        // Full name of the plugin (used for diagnostics).