Friday 6 December 2013

captcha Implementataion

Client Side Captcha Implementation JS function:

A CAPTCHA is a type of challenge-response test used in website as an attempt to ensure that the response is generated by a human being.
There are basically 3 types of captcha first one and widely used is image captcha ,
second is mathematical captcha and last one is vice captcha

Reference by code project:
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copy and paste the code to work for captcha. 
captcha.html
<html>
<head>
<title>Captcha</title>
   
    <script type="text/javascript">

   //Created / Generates the captcha function  
    function DrawCaptcha()
    {
        var a = Math.ceil(Math.random() * 10)+ '';
        var b = Math.ceil(Math.random() * 10)+ '';      
        var c = Math.ceil(Math.random() * 10)+ '';
        var d = Math.ceil(Math.random() * 10)+ '';
        var e = Math.ceil(Math.random() * 10)+ '';
        var f = Math.ceil(Math.random() * 10)+ '';
        var g = Math.ceil(Math.random() * 10)+ '';
        var code = a + ' ' + b + ' ' + ' ' + c + ' ' + d + ' ' + e + ' '+ f + ' ' + g;
        document.getElementById("txtCaptcha").value = code
    }

    // Validate the Entered input aganist the generated security code function  
    function ValidCaptcha(){
        var str1 = removeSpaces(document.getElementById('txtCaptcha').value);
        var str2 = removeSpaces(document.getElementById('txtInput').value);
        if (str1 == str2) return true;      
        return false;
       
    }

    // Remove the spaces from the entered and generated code
    function removeSpaces(string)
    {
        return string.split(' ').join('');
    }
   

    </script>
   
   
   
</head>
<body onLoad="DrawCaptcha();">
<table>
<tr>
    <td>
        Welcome To Captcha<br />
    </td>
</tr>
<tr>
    <td>
        <input type="text" id="txtCaptcha"
            style="background-image:url(1.jpg); text-align:center; border:none;
            font-weight:bold; font-family:Modern" />
        <input type="button" id="btnrefresh" value="Refresh" onClick="DrawCaptcha();" />
    </td>
</tr>
<tr>
    <td>
        <input type="text" id="txtInput"/>  
    </td>
</tr>
<tr>
    <td>
        <input id="Button1" type="button" value="Check" onClick="alert(ValidCaptcha());"/>
    </td>
</tr>
</table>
</body>
</html>

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