加密过滤器

加密过滤器特别适用于文件/数据流的加密。

mcrypt.* 和 mdecrypt.*

警告

本特性已自 PHP 7.1.0 起废弃。强烈建议不要使用本特性。

mcrypt.*mdecrypt.* 使用 libmcrypt 提供了对称的加密和解密。这两组过滤器都支持 mcrypt 扩展库中相同的算法,格式为 mcrypt.ciphername,其中 ciphername 是密码的名字,将被传递给 mcrypt_module_open()。有以下五个过滤器参数可用:

mcrypt 过滤器参数
参数 是否必须 默认值 取值举例
mode 可选 cbc cbc、cfb、ecb、nofb、ofb、stream
algorithms_dir 可选 ini_get('mcrypt.algorithms_dir') algorithms 模块的目录
modes_dir 可选 ini_get('mcrypt.modes_dir') modes 模块的目录
iv 必须 N/A 典型为 8、16 或 32 字节的二进制数据。根据密码而定
key 必须 N/A 典型为 8、16 或 32 字节的二进制数据。根据密码而定

示例 #1 用 Blowfish 算法加解密

<?php
// 假设之前已经生成了 $key
$iv_size = mcrypt_get_iv_size(MCRYPT_BLOWFISH, MCRYPT_MODE_CBC);
$iv = mcrypt_create_iv($iv_size, MCRYPT_DEV_URANDOM);
$fp = fopen('encrypted-file.enc', 'wb');
fwrite($fp, $iv);
$opts = array('mode'=>'cbc','iv'=>$iv, 'key'=>$key);
stream_filter_append($fp, 'mcrypt.blowfish', STREAM_FILTER_WRITE, $opts);
fwrite($fp, 'message to encrypt');
fclose($fp);

// 解密
$fp = fopen('encrypted-file.enc', 'rb');
$iv = fread($fp, $iv_size = mcrypt_get_iv_size(MCRYPT_BLOWFISH, MCRYPT_MODE_CBC));
$opts = array('mode'=>'cbc','iv'=>$iv, 'key'=>$key)
stream_filter_append($fp, 'mdecrypt.blowfish', STREAM_FILTER_READ, $opts);
$data = rtrim(stream_get_contents($fp));//trims off null padding
fclose($fp);
echo
$data;
?>

示例 #2 将文件以 SHA256 HMAC 的 AES-128 CBC 加密

<?php
AES_CBC
::encryptFile($password, "plaintext.txt", "encrypted.enc");
AES_CBC::decryptFile($password, "encrypted.enc", "decrypted.txt");

class
AES_CBC
{
protected static
$KEY_SIZES = array('AES-128'=>16,'AES-192'=>24,'AES-256'=>32);
protected static function
key_size() { return self::$KEY_SIZES['AES-128']; } //default AES-128
public static function encryptFile($password, $input_stream, $aes_filename){
$iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
$fin = fopen($input_stream, "rb");
$fc = fopen($aes_filename, "wb+");
if (!empty(
$fin) && !empty($fc)) {
fwrite($fc, str_repeat("_", 32) );//placeholder, SHA256 HMAC will go here later
fwrite($fc, $hmac_salt = mcrypt_create_iv($iv_size, MCRYPT_DEV_URANDOM));
fwrite($fc, $esalt = mcrypt_create_iv($iv_size, MCRYPT_DEV_URANDOM));
fwrite($fc, $iv = mcrypt_create_iv($iv_size, MCRYPT_DEV_URANDOM));
$ekey = hash_pbkdf2("sha256", $password, $esalt, $it=1000, self::key_size(), $raw=true);
$opts = array('mode'=>'cbc', 'iv'=>$iv, 'key'=>$ekey);
stream_filter_append($fc, 'mcrypt.rijndael-128', STREAM_FILTER_WRITE, $opts);
$infilesize = 0;
while (!
feof($fin)) {
$block = fread($fin, 8192);
$infilesize+=strlen($block);
fwrite($fc, $block);
}
$block_size = mcrypt_get_block_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
$padding = $block_size - ($infilesize % $block_size);//$padding is a number from 1-16
fwrite($fc, str_repeat(chr($padding), $padding) );//perform PKCS7 padding
fclose($fin);
fclose($fc);
$hmac_raw = self::calculate_hmac_after_32bytes($password, $hmac_salt, $aes_filename);
$fc = fopen($aes_filename, "rb+");
fwrite($fc, $hmac_raw);//overwrite placeholder
fclose($fc);
}
}
public static function
decryptFile($password, $aes_filename, $out_stream) {
$iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
$hmac_raw = file_get_contents($aes_filename, false, NULL, 0, 32);
$hmac_salt = file_get_contents($aes_filename, false, NULL, 32, $iv_size);
$hmac_calc = self::calculate_hmac_after_32bytes($password, $hmac_salt, $aes_filename);
$fc = fopen($aes_filename, "rb");
$fout = fopen($out_stream, 'wb');
if (!empty(
$fout) && !empty($fc) && self::hash_equals($hmac_raw,$hmac_calc)) {
fread($fc, 32+$iv_size);//skip sha256 hmac and salt
$esalt = fread($fc, $iv_size);
$iv = fread($fc, $iv_size);
$ekey = hash_pbkdf2("sha256", $password, $esalt, $it=1000, self::key_size(), $raw=true);
$opts = array('mode'=>'cbc', 'iv'=>$iv, 'key'=>$ekey);
stream_filter_append($fc, 'mdecrypt.rijndael-128', STREAM_FILTER_READ, $opts);
while (!
feof($fc)) {
$block = fread($fc, 8192);
if (
feof($fc)) {
$padding = ord($block[strlen($block) - 1]);//assume PKCS7 padding
$block = substr($block, 0, 0-$padding);
}
fwrite($fout, $block);
}
fclose($fout);
fclose($fc);
}
}
private static function
hash_equals($str1, $str2) {
if(
strlen($str1) == strlen($str2)) {
$res = $str1 ^ $str2;
for(
$ret=0,$i = strlen($res) - 1; $i >= 0; $i--) $ret |= ord($res[$i]);
return !
$ret;
}
return
false;
}
private static function
calculate_hmac_after_32bytes($password, $hsalt, $filename) {
static
$init=0;
$init or $init = stream_filter_register("user-filter.skipfirst32bytes", "FileSkip32Bytes");
$stream = 'php://filter/read=user-filter.skipfirst32bytes/resource=' . $filename;
$hkey = hash_pbkdf2("sha256", $password, $hsalt, $iterations=1000, 24, $raw=true);
return
hash_hmac_file('sha256', $stream, $hkey, $raw=true);
}
}
class
FileSkip32Bytes extends php_user_filter
{
private
$skipped=0;
function
filter($in, $out, &$consumed, $closing) {
while (
$bucket = stream_bucket_make_writeable($in)) {
$outlen = $bucket->datalen;
if (
$this->skipped<32){
$outlen = min($bucket->datalen,32-$this->skipped);
$bucket->data = substr($bucket->data, $outlen);
$bucket->datalen = $bucket->datalen-$outlen;
$this->skipped+=$outlen;
}
$consumed += $outlen;
stream_bucket_append($out, $bucket);
}
return
PSFS_PASS_ON;
}
}
class
AES_128_CBC extends AES_CBC {
protected static function
key_size() { return self::$KEY_SIZES['AES-128']; }
}
class
AES_192_CBC extends AES_CBC {
protected static function
key_size() { return self::$KEY_SIZES['AES-192']; }
}
class
AES_256_CBC extends AES_CBC {
protected static function
key_size() { return self::$KEY_SIZES['AES-256']; }
}
add a note

User Contributed Notes

There are no user contributed notes for this page.
To Top