php md5加密函数参考详解

<?
$str ="123456";
echo 'md5 16位'.md5($str,true);

//输出乱码

//如果你想得到php5中md5( "abc ",   true)这样的返回值，那么可以：
function   bin_md5($val)   {
    return   pack( "H32 ",md5($val));
}

echo '<br />md5 32位'.md5($str);

//10adc3949ba59abbe56e057f20f883e
?>

<?php
session_start();

if( isset($_POST['submit'])) {
   if( $_SESSION['security_code'] == $_POST['security_code'] && !empty($_SESSION['security_code'] ) ) {
  // Insert you code for processing the form here, e.g emailing the submission, entering it into a database.
  echo 'Thank you. Your message said "'.$_POST['message'].'"';
  unset($_SESSION['security_code']);
   } else {
  // Insert your code for showing an error message here
  echo 'Sorry, you have provided an invalid security code';
   }
} else {
?>

 <form action="form.php" method="post">
  <label for="name">Name: </label><input type="text" name="name" id="name" /><br />
  <label for="email">Email: </label><input type="text" name="email" id="email" /><br />
  <label for="message">Message: </label><textarea rows="5" cols="30" name="message" id="message"></textarea><br />
  <img src="CaptchaSecurityImages.php?width=100&height=40&characters=5" /><br />
  <label for="security_code">Security Code: </label><input id="security_code" name="security_code" type="text" /><br />
  <input type="submit" name="submit" value="Submit" />
 </form>

<?php
 }
?>

<?php
session_start();

/*
* File: CaptchaSecurityImages.php
* Author: Simon Jarvis
* Copyright: 2006 Simon Jarvis
* Date: 03/08/06
* Updated: 07/02/07
* Requirements: PHP 4/5 with GD and FreeType libraries
* Link: http://www.white-hat-web-design.co.uk/articles/php-captcha.php
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details:
* http://www.gnu.org/licenses/gpl.html
*
*/

class CaptchaSecurityImages {

 var $font = 'monofont.ttf';

 function generateCode($characters) {
  /* list all possible characters, similar looking characters and vowels have been removed */
  $possible = '23456789bcdfghjkmnpqrstvwxyz';
  $code = '';
  $i = 0;
  while ($i < $characters) {
   $code .= substr($possible, mt_rand(0, strlen($possible)-1), 1);
   $i++;
  }
  return $code;
 }

 function CaptchaSecurityImages($width='120',$height='40',$characters='6') {
  $code = $this->generateCode($characters);
  /* font size will be 75% of the image height */
  $font_size = $height * 0.75;
  $image = @imagecreate($width, $height) or die('Cannot initialize new GD image stream');
  /* set the colours */
  $background_color = imagecolorallocate($image, 255, 255, 255);
  $text_color = imagecolorallocate($image, 20, 40, 100);
  $noise_color = imagecolorallocate($image, 100, 120, 180);
  /* generate random dots in background */
  for( $i=0; $i<($width*$height)/3; $i++ ) {
   imagefilledellipse($image, mt_rand(0,$width), mt_rand(0,$height), 1, 1, $noise_color);
  }
  /* generate random lines in background */
  for( $i=0; $i<($width*$height)/150; $i++ ) {
   imageline($image, mt_rand(0,$width), mt_rand(0,$height), mt_rand(0,$width), mt_rand(0,$height), $noise_color);
  }
  /* create textbox and add text */
  $textbox = imagettfbbox($font_size, 0, $this->font, $code) or die('Error in imagettfbbox function');
  $x = ($width - $textbox[4])/2;
  $y = ($height - $textbox[5])/2;
  imagettftext($image, $font_size, 0, $x, $y, $text_color, $this->font , $code) or die('Error in imagettftext function');
  /* output captcha image to browser */
  header('Content-Type: image/jpeg');
  imagejpeg($image);
  imagedestroy($image);
  $_SESSION['security_code'] = $code;
 }

}

$width = isset($_GET['width']) ? $_GET['width'] : '120';
$height = isset($_GET['height']) ? $_GET['height'] : '40';
$characters = isset($_GET['characters']) && $_GET['characters'] > 1 ? $_GET['characters'] : '6';

$captcha = new CaptchaSecurityImages($width,$height,$characters);

?>

<?php
/*sql 注入 字符的检测
* 在所有用户输入的数据，post传参， get传参 都需要检测下 
* 如果有匹配到关键字 则 返回该关键字  否则返回false
* 这个和敏感字符的检测不是一样的
*/
function Filter_SQL($strData)
{
 $strFilter=$blnFlag=$arrayFilter='';

 $strFilter="'|and|(|)|exec|insert|select|delete|update|count|*|%27|chr|mid|master|truncate|char|declare|union|or"; //需要过滤的字符，可以自己添，"|"是分隔符
 $blnFlag=false;   //过滤标志，如果产生过滤，那么就是真
 
 $arr=explode("|",$strFilter); 
 $str="";
 
 foreach($arr as $row)
 {
  $str.=preg_quote($row)."|";
 } 
 
 $str=trim($str,"|"); 
 
 if(preg_match('/'.$str.'/i',$strData,$word))
 {
  return $word[0];
 }
 
 return false;
}

/*
测试
$string="fasdf union ";
echo Filter_SQL($string);
*/

?>

<?php教程
/*
 * Created on 2011-3-11
 * Programmer : xiaoyao, QQ:1045195056
 验证通过判断输入值与$_SESSION['check_pic']值
 */
session_start();
 function RandAscii($number){//$number产生数字和字母个数
$arr=array('0','1','2','3','4','5','6','7','8','9',
'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','w','v','u','x','y','z');
for ($i=1;$i<=$number;$i++)
{
$rand= $rand.$arr[rand(0,35)];
}
return $rand;
}
 $rand=RandAscii(4);

$_SESSION['check_pic']=$rand;//随机产生的四个数赋值session中，用于验证。
$x=80;
$y=24;
 $im=imagecreatetruecolor($x,$y);//创建图片
$bg=imagecolorallocate($im,255,255,255);//设置颜色背景
imagefill( $im,0,0,$bg);
$wh=imagecolorallocate($im,255,255,0);
$grey=imagecolorallocate($im,128,128,128);
$yellow=imagecolorallocate($im,255,255,0);
$red=imagecolorallocate($im,0,255,0);
$foregroundArr = array(imagecolorallocate($im, rand(0, 20), rand(0, 20), rand(0, 20)),
  imagecolorallocate($im, rand(0, 20), rand(0, 10), rand(245, 255)),
  imagecolorallocate($im, rand(245, 255), rand(0, 20), rand(0, 10)),
  imagecolorallocate($im, rand(245, 255), rand(0, 20), rand(245, 255))
 );//字颜色数组
 //画边框
 $border = imagecolorallocate($im, 133, 153, 193);
 imagerectangle($im, 0, 0, $x - 1, $y - 1, $border);

for($i=0;$i<10;$i++){        //画干扰线，10条
imageline($im,rand(0,60),2,rand(0,60),20,$yellow);

}
for($j=0;$j<100;$j++){
 imagesetpixel($im,rand()%76,rand()%20,$red);
}
//imagestring($im,6,15,8,$rand,$wh);//字体大小1-5
imagettftext($im, 14,rand(30, -30), 5, rand(15, 18) ,$foregroundArr[rand(0,3)], 'C:WindowsFontsArial.ttf',$rand[0]);
imagettftext($im, 14,rand(50, -50), 24, rand(15, 18),$foregroundArr[rand(0,3)], 'C:WindowsFontsArial.ttf',$rand[1]);
imagettftext($im, 14,rand(50, -50), 43, rand(15, 18) ,$foregroundArr[rand(0,3)], 'C:WindowsFontsArial.ttf',$rand[2]);
imagettftext($im, 14,rand(30, -30), 62, rand(15, 18),$foregroundArr[rand(0,3)], 'C:WindowsFontsArial.ttf',$rand[3]);

header("Content-type: image/jpeg");//输出图片
imagejpeg($im);
imagedestroy($im);
?>