mcrypt_generic()

(PHP 4 >= 4.0.2, PHP 5, PHP 7 < 7.2.0, PECL mcrypt >= 1.0.0)

加密数据

Warning

This function has beenDEPRECATEDas of PHP 7.1.0. Relying on this functionis highly discouraged.

说明

mcrypt_generic(resource $td,string $data): string

本函数用来加密数据。传入数据长度必须是 n *分组大小，否则需要后补"0"。本函数返回加密后的数据。注意，根据数据补齐不同，返回的数据可能比输入的数据长度有所增加。

如果你需要把加密后的数据保存到数据库，请确保保存 mcrypt_generic 返回的完整的字符串，否则将无法正确解密。如果原始数据有 10 个字符，分组大小为 8 （使用mcrypt_enc_get_block_size()获取分组大小），则数据库中至少需要 16 个字符来保存数据。请注意mdecrypt_generic()函数返回的数据也会是 16 个字符。使用 rtrim($str,"0")移除字符串末尾的 0 。

如果你在例如 MySQL 这样的数据库中存储数据，请注意 varchar 类型的字段会在插入数据时自动移除字符串末尾的“空格”。由于加密后的数据可能是以空格（ASCII 32）结尾，这种特性会导致数据损坏。请使用 tinyblob/tinytext（或 larger）字段来存储加密数据。

参数

$td

加密描述符。

在调用本函数之前，请使用mcrypt_generic_init()函数初始化加密句柄。在加密完成之后，需要调用mcrypt_generic_deinit()函数进行必要的清理工作。请参见mcrypt_module_open()。

$data

要加密的数据。

返回值

返回加密后的数据。

参见

• mdecrypt_generic()解密数据
• mcrypt_generic_init()初始化加密所需的缓冲区
• mcrypt_generic_deinit()对加密模块进行清理工作

completing the post from Ryan Thomas, ryanrst at gmail dot com, if u post a cookie w/ HTTP method, its may be encoded;
As some chars in base64 will be encoded to another things, u can just replace them before encode and after decode;
Its a tweak from dawgeatschikin at hotmail dot com to original idea from massimo dot scamarcia at gmail dot com
(see @ http://www.php.net/manual/en/function.base64-encode.php):
<?php 
function urlsafe_b64encode($string)
{
 $data = base64_encode($string);
 $data = str_replace(array('+','/','='),array('-','_','.'),$data);
 return $data;
}
function urlsafe_b64decode($string)
{
 $data = str_replace(array('-','_','.'),array('+','/','='),$string);
 $mod4 = strlen($data) % 4;
 if ($mod4) {
  $data .= substr('====', $mod4);
 }
 return base64_decode($data);
}
?>

If you wish to store encrypted data in a cookie variable on the browser you will encounter problems when decrypting the data. This is because cookies will only store US-ASCII characters and your encrypted data may contain non-US-ASCII characters.
The solution: 
base64_encode your encrypted string before you store it in the cookie and base64_decode the string stored in the cookie becore decrypting.
Example:
function setEncryptedCookie($cookieName, $data)
{
 setcookie($cookieName, base64_encode($this->encrypt($data)), time()+$this->expire); 
}
function getEncryptedCookie($cookieName)
{
 return $this->decrypt(base64_decode($_COOKIE[$cookieName]));
}

If the data is already n*blocksize long, PHP pads with another full block of "\0", so there will be between 1 and mcrypt_enc_get_block_size($td) bytes of padding.
You can create binary-safe padding by unconditionally adding a 0x80 to the string, then stripping trailing "\0"s PHP added, plus the one 0x80 byte.
<?php
function pad($text) {
 // Add a single 0x80 byte and let PHP pad with 0x00 bytes.
 return pack("a*H2", $text, "80");
}
function unpad($text) {
 // Return all but the trailing 0x80 from text that had the 0x00 bytes removed
 return substr(rtrim($text, "\0"), 0, -1);
}
?>

Behaviour change: Since 5.2.x mcrypt_generic will issue a warning when the datastring is empty.

Addendum to my previous note: apparently there was some sort of character encoding breakage; PHP does not pad if no padding is needed, and the extra padding I saw was the result of chr(X) returning multiple bytes or something.
The pad/unpad functions I gave are still binary-safe, though, and are to the best of my knowledge completely compatible with NIST 800-38a.

I was able get php and perl to play together with blowfish using cipher block chaining. The blowfish key needs to be atleast 8 chars (even though blowfish min is 8 bits, perl didn't like keys smaller than 8 chars) and max 56. The iv must be exactly 8 chars and padding needs to be null because php pads with nulls. Also, php needs libmcrypt >= 2.4.9 to be compatible with perl.
PERL
----
use Crypt::CBC;
$cipher = Crypt::CBC->new( {'key' => 'my secret key',
                  'cipher'=> 'Blowfish',
                  'iv' => '12345678',
                  'regenerate_key' => 0,
                  'padding' => 'null',
                  'prepend_iv' => 0
                  });
$cc = 'my secret text';
$encrypted = $cipher->encrypt($cc);
$decrypted = $cipher->decrypt($encrypted);
print "encrypted : ".$encrypted;
print "<br>";
print "decrypted : ".$decrypted;
PHP
---
$cc = 'my secret text';
$key = 'my secret key';
$iv = '12345678';
$cipher = mcrypt_module_open(MCRYPT_BLOWFISH,'','cbc','');
mcrypt_generic_init($cipher, $key, $iv);
$encrypted = mcrypt_generic($cipher,$cc);
mcrypt_generic_deinit($cipher);
mcrypt_generic_init($cipher, $key, $iv);
$decrypted = mdecrypt_generic($cipher,$encrypted);
mcrypt_generic_deinit($cipher);
echo "encrypted : ".$encrypted;
echo "<br>";
echo "decrypted : ".$decrypted;

If you are encrypting binary and there is a null terminator partway through your encryption, you will loose the rest of the string. A workaround is to base64_encode your binary string first.
We found this problem while trying to encrypt CC information. Some CC values would not decrypt after we converted them to a binary string.
We were using the MCRYPT_RIJNDAEL_256 module to encrypt with.
Hope this helps someone.