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<?php
/**
* OpenSSH Key Handler
*
* PHP version 5
*
* Place in $HOME/.ssh/authorized_keys
*
* @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\Random;
/**
* OpenSSH Formatted RSA Key Handler
*
* @author Jim Wigginton <terrafrost@php.net>
*/
abstract class OpenSSH
{
/**
* Default comment
*
* @var string
*/
protected static $comment = 'phpseclib-generated-key';
/**
* Binary key flag
*
* @var bool
*/
protected static $binary = false;
/**
* Sets the default comment
*
* @param string $comment
*/
public static function setComment($comment)
{
self::$comment = str_replace(["\r", "\n"], '', $comment);
}
/**
* Break a public or private key down into its constituent components
*
* $type can be either ssh-dss or ssh-rsa
*
* @param string $key
* @param string $password
* @return array
*/
public static function load($key, $password = '')
{
if (!Strings::is_stringable($key)) {
throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key));
}
// key format is described here:
// https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/PROTOCOL.key?annotate=HEAD
if (strpos($key, 'BEGIN OPENSSH PRIVATE KEY') !== false) {
$key = preg_replace('#(?:^-.*?-[\r\n]*$)|\s#ms', '', $key);
$key = Strings::base64_decode($key);
$magic = Strings::shift($key, 15);
if ($magic != "openssh-key-v1\0") {
throw new \RuntimeException('Expected openssh-key-v1');
}
list($ciphername, $kdfname, $kdfoptions, $numKeys) = Strings::unpackSSH2('sssN', $key);
if ($numKeys != 1) {
// if we wanted to support multiple keys we could update PublicKeyLoader to preview what the # of keys
// would be; it'd then call Common\Keys\OpenSSH.php::load() and get the paddedKey. it'd then pass
// that to the appropriate key loading parser $numKey times or something
throw new \RuntimeException('Although the OpenSSH private key format supports multiple keys phpseclib does not');
}
switch ($ciphername) {
case 'none':
break;
case 'aes256-ctr':
if ($kdfname != 'bcrypt') {
throw new \RuntimeException('Only the bcrypt kdf is supported (' . $kdfname . ' encountered)');
}
list($salt, $rounds) = Strings::unpackSSH2('sN', $kdfoptions);
$crypto = new AES('ctr');
//$crypto->setKeyLength(256);
//$crypto->disablePadding();
$crypto->setPassword($password, 'bcrypt', $salt, $rounds, 32);
break;
default:
throw new \RuntimeException('The only supported cipherse are: none, aes256-ctr (' . $ciphername . ' is being used)');
}
list($publicKey, $paddedKey) = Strings::unpackSSH2('ss', $key);
list($type) = Strings::unpackSSH2('s', $publicKey);
if (isset($crypto)) {
$paddedKey = $crypto->decrypt($paddedKey);
}
list($checkint1, $checkint2) = Strings::unpackSSH2('NN', $paddedKey);
// any leftover bytes in $paddedKey are for padding? but they should be sequential bytes. eg. 1, 2, 3, etc.
if ($checkint1 != $checkint2) {
throw new \RuntimeException('The two checkints do not match');
}
self::checkType($type);
return compact('type', 'publicKey', 'paddedKey');
}
$parts = explode(' ', $key, 3);
if (!isset($parts[1])) {
$key = base64_decode($parts[0]);
$comment = false;
} else {
$asciiType = $parts[0];
self::checkType($parts[0]);
$key = base64_decode($parts[1]);
$comment = isset($parts[2]) ? $parts[2] : false;
}
if ($key === false) {
throw new \UnexpectedValueException('Key should be a string - not a ' . gettype($key));
}
list($type) = Strings::unpackSSH2('s', $key);
self::checkType($type);
if (isset($asciiType) && $asciiType != $type) {
throw new \RuntimeException('Two different types of keys are claimed: ' . $asciiType . ' and ' . $type);
}
if (strlen($key) <= 4) {
throw new \UnexpectedValueException('Key appears to be malformed');
}
$publicKey = $key;
return compact('type', 'publicKey', 'comment');
}
/**
* Toggle between binary and printable keys
*
* Printable keys are what are generated by default. These are the ones that go in
* $HOME/.ssh/authorized_key.
*
* @param bool $enabled
*/
public static function setBinaryOutput($enabled)
{
self::$binary = $enabled;
}
/**
* Checks to see if the type is valid
*
* @param string $candidate
*/
private static function checkType($candidate)
{
if (!in_array($candidate, static::$types)) {
throw new \RuntimeException("The key type ($candidate) is not equal to: " . implode(',', static::$types));
}
}
/**
* Wrap a private key appropriately
*
* @param string $publicKey
* @param string $privateKey
* @param string $password
* @param array $options
* @return string
*/
protected static function wrapPrivateKey($publicKey, $privateKey, $password, $options)
{
list(, $checkint) = unpack('N', Random::string(4));
$comment = isset($options['comment']) ? $options['comment'] : self::$comment;
$paddedKey = Strings::packSSH2('NN', $checkint, $checkint) .
$privateKey .
Strings::packSSH2('s', $comment);
$usesEncryption = !empty($password) && is_string($password);
/*
from http://tools.ietf.org/html/rfc4253#section-6 :
Note that the length of the concatenation of 'packet_length',
'padding_length', 'payload', and 'random padding' MUST be a multiple
of the cipher block size or 8, whichever is larger.
*/
$blockSize = $usesEncryption ? 16 : 8;
$paddingLength = (($blockSize - 1) * strlen($paddedKey)) % $blockSize;
for ($i = 1; $i <= $paddingLength; $i++) {
$paddedKey .= chr($i);
}
if (!$usesEncryption) {
$key = Strings::packSSH2('sssNss', 'none', 'none', '', 1, $publicKey, $paddedKey);
} else {
$rounds = isset($options['rounds']) ? $options['rounds'] : 16;
$salt = Random::string(16);
$kdfoptions = Strings::packSSH2('sN', $salt, $rounds);
$crypto = new AES('ctr');
$crypto->setPassword($password, 'bcrypt', $salt, $rounds, 32);
$paddedKey = $crypto->encrypt($paddedKey);
$key = Strings::packSSH2('sssNss', 'aes256-ctr', 'bcrypt', $kdfoptions, 1, $publicKey, $paddedKey);
}
$key = "openssh-key-v1\0$key";
return "-----BEGIN OPENSSH PRIVATE KEY-----\n" .
chunk_split(Strings::base64_encode($key), 70, "\n") .
"-----END OPENSSH PRIVATE KEY-----\n";
}
}
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