function validateAmount()

{

    var theAmount = document.forms["frmCreditCardPayment"].AMT.value;

    if (isEmpty(theAmount))

    {

        alert("Please enter your payment amount");

        document.forms["frmCreditCardPayment"].AMT.focus();

        return false;

    }

    else

    {

        if (!isDecimalNumber(theAmount))

        {

            alert("Payment amount should be a valid decimal number");

            document.forms["frmCreditCardPayment"].AMT.select();

            document.forms["frmCreditCardPayment"].AMT.focus();

            return false;

        }

        else

        {

            document.forms["frmCreditCardPayment"].AMT.value = formatCurrency(theAmount);

            sValString = document.forms["frmCreditCardPayment"].POSTING_KEY.value + document.forms["frmCreditCardPayment"].EXT_TRANS_ID.value + document.forms["frmCreditCardPayment"].AMT.value;

            var sKeyString = b64_md5(sValString);

            document.forms["frmCreditCardPayment"].VALIDATION_KEY.value = sKeyString;

            return true;

        }

    }

}



var b64pad  = "="; /* base-64 pad character. "=" for strict RFC compliance   */

var chrsz   = 8;  /* bits per input character. 8 - ASCII; 16 - Unicode      */



function b64_md5(s){ return binl2b64(core_md5(str2binl(s), s.length * chrsz));}



/*

 * Calculate the MD5 of an array of little-endian words, and a bit length

 */

function core_md5(x, len)

{

  /* append padding */

  x[len >> 5] |= 0x80 << ((len) % 32);

  x[(((len + 64) >>> 9) << 4) + 14] = len;



  var a =  1732584193;

  var b = -271733879;

  var c = -1732584194;

  var d =  271733878;



  for(var i = 0; i < x.length; i += 16)

  {

    var olda = a;

    var oldb = b;

    var oldc = c;

    var oldd = d;



    a = md5_ff(a, b, c, d, x[i+ 0], 7 , -680876936);

    d = md5_ff(d, a, b, c, x[i+ 1], 12, -389564586);

    c = md5_ff(c, d, a, b, x[i+ 2], 17,  606105819);

    b = md5_ff(b, c, d, a, x[i+ 3], 22, -1044525330);

    a = md5_ff(a, b, c, d, x[i+ 4], 7 , -176418897);

    d = md5_ff(d, a, b, c, x[i+ 5], 12,  1200080426);

    c = md5_ff(c, d, a, b, x[i+ 6], 17, -1473231341);

    b = md5_ff(b, c, d, a, x[i+ 7], 22, -45705983);

    a = md5_ff(a, b, c, d, x[i+ 8], 7 ,  1770035416);

    d = md5_ff(d, a, b, c, x[i+ 9], 12, -1958414417);

    c = md5_ff(c, d, a, b, x[i+10], 17, -42063);

    b = md5_ff(b, c, d, a, x[i+11], 22, -1990404162);

    a = md5_ff(a, b, c, d, x[i+12], 7 ,  1804603682);

    d = md5_ff(d, a, b, c, x[i+13], 12, -40341101);

    c = md5_ff(c, d, a, b, x[i+14], 17, -1502002290);

    b = md5_ff(b, c, d, a, x[i+15], 22,  1236535329);



    a = md5_gg(a, b, c, d, x[i+ 1], 5 , -165796510);

    d = md5_gg(d, a, b, c, x[i+ 6], 9 , -1069501632);

    c = md5_gg(c, d, a, b, x[i+11], 14,  643717713);

    b = md5_gg(b, c, d, a, x[i+ 0], 20, -373897302);

    a = md5_gg(a, b, c, d, x[i+ 5], 5 , -701558691);

    d = md5_gg(d, a, b, c, x[i+10], 9 ,  38016083);

    c = md5_gg(c, d, a, b, x[i+15], 14, -660478335);

    b = md5_gg(b, c, d, a, x[i+ 4], 20, -405537848);

    a = md5_gg(a, b, c, d, x[i+ 9], 5 ,  568446438);

    d = md5_gg(d, a, b, c, x[i+14], 9 , -1019803690);

    c = md5_gg(c, d, a, b, x[i+ 3], 14, -187363961);

    b = md5_gg(b, c, d, a, x[i+ 8], 20,  1163531501);

    a = md5_gg(a, b, c, d, x[i+13], 5 , -1444681467);

    d = md5_gg(d, a, b, c, x[i+ 2], 9 , -51403784);

    c = md5_gg(c, d, a, b, x[i+ 7], 14,  1735328473);

    b = md5_gg(b, c, d, a, x[i+12], 20, -1926607734);



    a = md5_hh(a, b, c, d, x[i+ 5], 4 , -378558);

    d = md5_hh(d, a, b, c, x[i+ 8], 11, -2022574463);

    c = md5_hh(c, d, a, b, x[i+11], 16,  1839030562);

    b = md5_hh(b, c, d, a, x[i+14], 23, -35309556);

    a = md5_hh(a, b, c, d, x[i+ 1], 4 , -1530992060);

    d = md5_hh(d, a, b, c, x[i+ 4], 11,  1272893353);

    c = md5_hh(c, d, a, b, x[i+ 7], 16, -155497632);

    b = md5_hh(b, c, d, a, x[i+10], 23, -1094730640);

    a = md5_hh(a, b, c, d, x[i+13], 4 ,  681279174);

    d = md5_hh(d, a, b, c, x[i+ 0], 11, -358537222);

    c = md5_hh(c, d, a, b, x[i+ 3], 16, -722521979);

    b = md5_hh(b, c, d, a, x[i+ 6], 23,  76029189);

    a = md5_hh(a, b, c, d, x[i+ 9], 4 , -640364487);

    d = md5_hh(d, a, b, c, x[i+12], 11, -421815835);

    c = md5_hh(c, d, a, b, x[i+15], 16,  530742520);

    b = md5_hh(b, c, d, a, x[i+ 2], 23, -995338651);



    a = md5_ii(a, b, c, d, x[i+ 0], 6 , -198630844);

    d = md5_ii(d, a, b, c, x[i+ 7], 10,  1126891415);

    c = md5_ii(c, d, a, b, x[i+14], 15, -1416354905);

    b = md5_ii(b, c, d, a, x[i+ 5], 21, -57434055);

    a = md5_ii(a, b, c, d, x[i+12], 6 ,  1700485571);

    d = md5_ii(d, a, b, c, x[i+ 3], 10, -1894986606);

    c = md5_ii(c, d, a, b, x[i+10], 15, -1051523);

    b = md5_ii(b, c, d, a, x[i+ 1], 21, -2054922799);

    a = md5_ii(a, b, c, d, x[i+ 8], 6 ,  1873313359);

    d = md5_ii(d, a, b, c, x[i+15], 10, -30611744);

    c = md5_ii(c, d, a, b, x[i+ 6], 15, -1560198380);

    b = md5_ii(b, c, d, a, x[i+13], 21,  1309151649);

    a = md5_ii(a, b, c, d, x[i+ 4], 6 , -145523070);

    d = md5_ii(d, a, b, c, x[i+11], 10, -1120210379);

    c = md5_ii(c, d, a, b, x[i+ 2], 15,  718787259);

    b = md5_ii(b, c, d, a, x[i+ 9], 21, -343485551);



    a = safe_add(a, olda);

    b = safe_add(b, oldb);

    c = safe_add(c, oldc);

    d = safe_add(d, oldd);

  }

  return Array(a, b, c, d);



}



/*

 * These functions implement the four basic operations the algorithm uses.

 */

function md5_cmn(q, a, b, x, s, t)

{

  return safe_add(bit_rol(safe_add(safe_add(a, q), safe_add(x, t)), s),b);

}

function md5_ff(a, b, c, d, x, s, t)

{

  return md5_cmn((b & c) | ((~b) & d), a, b, x, s, t);

}

function md5_gg(a, b, c, d, x, s, t)

{

  return md5_cmn((b & d) | (c & (~d)), a, b, x, s, t);

}

function md5_hh(a, b, c, d, x, s, t)

{

  return md5_cmn(b ^ c ^ d, a, b, x, s, t);

}

function md5_ii(a, b, c, d, x, s, t)

{

  return md5_cmn(c ^ (b | (~d)), a, b, x, s, t);

}



/*

 * Add integers, wrapping at 2^32. This uses 16-bit operations internally

 * to work around bugs in some JS interpreters.

 */

function safe_add(x, y)

{

  var lsw = (x & 0xFFFF) + (y & 0xFFFF);

  var msw = (x >> 16) + (y >> 16) + (lsw >> 16);

  return (msw << 16) | (lsw & 0xFFFF);

}



/*

 * Bitwise rotate a 32-bit number to the left.

 */

function bit_rol(num, cnt)

{

  return (num << cnt) | (num >>> (32 - cnt));

}



/*

 * Convert a string to an array of little-endian words

 * If chrsz is ASCII, characters >255 have their hi-byte silently ignored.

 */

function str2binl(str)

{

  var bin = Array();

  var mask = (1 << chrsz) - 1;

  for(var i = 0; i < str.length * chrsz; i += chrsz)

    bin[i>>5] |= (str.charCodeAt(i / chrsz) & mask) << (i%32);

  return bin;

}



/*

 * Convert an array of little-endian words to a base-64 string

 */

function binl2b64(binarray)

{

  var tab = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

  var str = "";

  for(var i = 0; i < binarray.length * 4; i += 3)

  {

    var triplet = (((binarray[i   >> 2] >> 8 * ( i   %4)) & 0xFF) << 16)

                | (((binarray[i+1 >> 2] >> 8 * ((i+1)%4)) & 0xFF) << 8 )

                |  ((binarray[i+2 >> 2] >> 8 * ((i+2)%4)) & 0xFF);

    for(var j = 0; j < 4; j++)

    {

      if(i * 8 + j * 6 > binarray.length * 32) str += b64pad;

      else str += tab.charAt((triplet >> 6*(3-j)) & 0x3F);

    }

  }

  return str;

}



