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<?php
/**
* PKCS1 Formatted Key Handler
*
* PHP version 5
*
* @author Jim Wigginton <terrafrost@php.net>
* @copyright 2015 Jim Wigginton
* @license http://www.opensource.org/licenses/mit-license.html MIT License
* @link http://phpseclib.sourceforge.net
*/
namespace phpseclib3\Crypt\Common\Formats\Keys;
use phpseclib3\Common\Functions\Strings;
use phpseclib3\Crypt\AES;
use phpseclib3\Crypt\DES;
use phpseclib3\Crypt\Random;
use phpseclib3\Crypt\TripleDES;
use phpseclib3\Exception\UnsupportedAlgorithmException;
use phpseclib3\File\ASN1;
/**
* PKCS1 Formatted Key Handler
*
* @author Jim Wigginton <terrafrost@php.net>
*/
abstract class PKCS1 extends PKCS
{
/**
* Default encryption algorithm
*
* @var string
*/
private static $defaultEncryptionAlgorithm = 'AES-128-CBC';
/**
* Sets the default encryption algorithm
*
* @param string $algo
*/
public static function setEncryptionAlgorithm($algo)
{
self::$defaultEncryptionAlgorithm = $algo;
}
/**
* Returns the mode constant corresponding to the mode string
*
* @param string $mode
* @return int
* @throws \UnexpectedValueException if the block cipher mode is unsupported
*/
private static function getEncryptionMode($mode)
{
switch ($mode) {
case 'CBC':
case 'ECB':
case 'CFB':
case 'OFB':
case 'CTR':
return $mode;
}
throw new \UnexpectedValueException('Unsupported block cipher mode of operation');
}
/**
* Returns a cipher object corresponding to a string
*
* @param string $algo
* @return string
* @throws \UnexpectedValueException if the encryption algorithm is unsupported
*/
private static function getEncryptionObject($algo)
{
$modes = '(CBC|ECB|CFB|OFB|CTR)';
switch (true) {
case preg_match("#^AES-(128|192|256)-$modes$#", $algo, $matches):
$cipher = new AES(self::getEncryptionMode($matches[2]));
$cipher->setKeyLength($matches[1]);
return $cipher;
case preg_match("#^DES-EDE3-$modes$#", $algo, $matches):
return new TripleDES(self::getEncryptionMode($matches[1]));
case preg_match("#^DES-$modes$#", $algo, $matches):
return new DES(self::getEncryptionMode($matches[1]));
default:
throw new UnsupportedAlgorithmException($algo . ' is not a supported algorithm');
}
}
/**
* Generate a symmetric key for PKCS#1 keys
*
* @param string $password
* @param string $iv
* @param int $length
* @return string
*/
private static function generateSymmetricKey($password, $iv, $length)
{
$symkey = '';
$iv = substr($iv, 0, 8);
while (strlen($symkey) < $length) {
$symkey .= md5($symkey . $password . $iv, true);
}
return substr($symkey, 0, $length);
}
/**
* Break a public or private key down into its constituent components
*
* @param string $key
* @param string $password optional
* @return array
*/
protected static function load($key, $password)
{
if (!Strings::is_stringable($key)) {
throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key));
}
/* Although PKCS#1 proposes a format that public and private keys can use, encrypting them is
"outside the scope" of PKCS#1. PKCS#1 then refers you to PKCS#12 and PKCS#15 if you're wanting to
protect private keys, however, that's not what OpenSSL* does. OpenSSL protects private keys by adding
two new "fields" to the key - DEK-Info and Proc-Type. These fields are discussed here:
http://tools.ietf.org/html/rfc1421#section-4.6.1.1
http://tools.ietf.org/html/rfc1421#section-4.6.1.3
DES-EDE3-CBC as an algorithm, however, is not discussed anywhere, near as I can tell.
DES-CBC and DES-EDE are discussed in RFC1423, however, DES-EDE3-CBC isn't, nor is its key derivation
function. As is, the definitive authority on this encoding scheme isn't the IETF but rather OpenSSL's
own implementation. ie. the implementation *is* the standard and any bugs that may exist in that
implementation are part of the standard, as well.
* OpenSSL is the de facto standard. It's utilized by OpenSSH and other projects */
if (preg_match('#DEK-Info: (.+),(.+)#', $key, $matches)) {
$iv = Strings::hex2bin(trim($matches[2]));
// remove the Proc-Type / DEK-Info sections as they're no longer needed
$key = preg_replace('#^(?:Proc-Type|DEK-Info): .*#m', '', $key);
$ciphertext = ASN1::extractBER($key);
if ($ciphertext === false) {
$ciphertext = $key;
}
$crypto = self::getEncryptionObject($matches[1]);
$crypto->setKey(self::generateSymmetricKey($password, $iv, $crypto->getKeyLength() >> 3));
$crypto->setIV($iv);
$key = $crypto->decrypt($ciphertext);
} else {
if (self::$format != self::MODE_DER) {
$decoded = ASN1::extractBER($key);
if ($decoded !== false) {
$key = $decoded;
} elseif (self::$format == self::MODE_PEM) {
throw new \UnexpectedValueException('Expected base64-encoded PEM format but was unable to decode base64 text');
}
}
}
return $key;
}
/**
* Wrap a private key appropriately
*
* @param string $key
* @param string $type
* @param string $password
* @param array $options optional
* @return string
*/
protected static function wrapPrivateKey($key, $type, $password, array $options = [])
{
if (empty($password) || !is_string($password)) {
return "-----BEGIN $type PRIVATE KEY-----\r\n" .
chunk_split(Strings::base64_encode($key), 64) .
"-----END $type PRIVATE KEY-----";
}
$encryptionAlgorithm = isset($options['encryptionAlgorithm']) ? $options['encryptionAlgorithm'] : self::$defaultEncryptionAlgorithm;
$cipher = self::getEncryptionObject($encryptionAlgorithm);
$iv = Random::string($cipher->getBlockLength() >> 3);
$cipher->setKey(self::generateSymmetricKey($password, $iv, $cipher->getKeyLength() >> 3));
$cipher->setIV($iv);
$iv = strtoupper(Strings::bin2hex($iv));
return "-----BEGIN $type PRIVATE KEY-----\r\n" .
"Proc-Type: 4,ENCRYPTED\r\n" .
"DEK-Info: " . $encryptionAlgorithm . ",$iv\r\n" .
"\r\n" .
chunk_split(Strings::base64_encode($cipher->encrypt($key)), 64) .
"-----END $type PRIVATE KEY-----";
}
/**
* Wrap a public key appropriately
*
* @param string $key
* @param string $type
* @return string
*/
protected static function wrapPublicKey($key, $type)
{
return "-----BEGIN $type PUBLIC KEY-----\r\n" .
chunk_split(Strings::base64_encode($key), 64) .
"-----END $type PUBLIC KEY-----";
}
}
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