php自定义加密与解密程序实例

$ralphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890 !,.:;?~@#$%^&*()_+-=][}{/><"'";?
$alphabet = $ralphabet . $ralphabet;
?
class Crypto {
?
function encrypt ($password,$strtoencrypt) {
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global $ralphabet;?
global $alphabet;
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for( $i=0; $i<strlen($password); $i++ )?
{?
$cur_pswd_ltr = substr($password,$i,1);?
$pos_alpha_ary[] = substr(strstr($alphabet,$cur_pswd_ltr),strlen($ralphabet));?
}
?
$i=0;?
$n = 0;?
$nn = strlen($password);?
$c = strlen($strtoencrypt);
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while($i<$c)?
{?
$encrypted_string .= substr($pos_alpha_ary[$n],strpos($ralphabet,substr($strtoencrypt,1)),1);
?
$n++;?
if($n==$nn) $n = 0;?
$i++;?
}
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return $encrypted_string;
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}
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function decrypt ($password,$strtodecrypt) {
?
global $ralphabet;?
global $alphabet;
?
for( $i=0; $i<strlen($password); $i++ )?
{?
$cur_pswd_ltr = substr($password,strlen($ralphabet));?
}
?
$i=0;?
$n = 0;?
$nn = strlen($password);?
$c = strlen($strtodecrypt);
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while($i<$c)?
{?
$decrypted_string .= substr($ralphabet,strpos($pos_alpha_ary[$n],substr($strtodecrypt,1);
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$n++;?
if($n==$nn) $n = 0;?
$i++;?
}
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return $decrypted_string;
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}
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function cryption_table ($password) {
?
global $ralphabet;?
global $alphabet;
?
for( $i=0; $i<strlen($password); $i++ )?
{?
$cur_pswd_ltr = substr($password,strlen($ralphabet));?
}
?
print "<table border=1 cellpadding="0" cellspacing="0">n";
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print "<tr><td></td>";?
for( $j=0; $j<strlen($ralphabet); $j++ )?
{?
print "<td align="center"><font size="2" face="arial">" . substr($ralphabet,$j,1) . "</td>n";?
}?
print "</tr>";
?
?
for( $i=0; $i<count($pos_alpha_ary); $i++ )?
{?
print "<tr><td align="right"><font size="2"><b>" . ($i+1) . "|</b></font></td>";?
for( $k=0; $k<strlen($pos_alpha_ary[$i]); $k++ )?
{?
print "<td align="center"><font size="2" face="arial">" . substr($pos_alpha_ary[$i],$k,1) . "</td>n";?
}?
print "</tr>";?
}
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print "</table>n";
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}
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} // end class Crypto
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// Example written by Macro Zeng?
$ct = new Crypto;?
//$ct->cryption_table($password);?
echo "<form action=$PHP_SELF method=post>";?
if ($mod == 2) {?
$strtodecrypt = $ct->encrypt ($password,$strtoencrypt);?
echo 'Encrypted String(加密后的字段): ';?
echo "<input type=text name=strtodecrypt size=45 value=$strtodecrypt>";?
echo "暗码锁: <input type=text name=password size=6 value=$password>";?
echo "<input type=submit value="Decrypt(解密)">";?
}?
else {?
$strtoencrypt = $ct->decrypt ($password,$strtodecrypt);?
echo 'String to Encrypt(需要加密的字段): ';?
echo "<input type=text name=strtoencrypt size=45 value=$strtoencrypt>";?
echo "暗码锁: <input type=text name=password size=6 value=$password>";?
echo "<input type=submit value="Encrypt(加密)">";?
echo "<input type=hidden name=mod value=2>";?
}?
echo "</form>";

highlight_file("crypto.php");