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<?php
/**
* PuTTY Formatted Key Handler
*
* See PuTTY's SSHPUBK.C and https://tartarus.org/~simon/putty-snapshots/htmldoc/AppendixC.html
*
* PHP version 5
*
* @author Jim Wigginton <terrafrost@php.net>
* @copyright 2016 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\Hash;
use phpseclib3\Crypt\Random;
use phpseclib3\Exception\UnsupportedAlgorithmException;
/**
* PuTTY Formatted Key Handler
*
* @author Jim Wigginton <terrafrost@php.net>
*/
abstract class PuTTY
{
/**
* Default comment
*
* @var string
*/
private static $comment = 'phpseclib-generated-key';
/**
* Default version
*
* @var int
*/
private static $version = 2;
/**
* Sets the default comment
*
* @param string $comment
*/
public static function setComment($comment)
{
self::$comment = str_replace(["\r", "\n"], '', $comment);
}
/**
* Sets the default version
*
* @param int $version
*/
public static function setVersion($version)
{
if ($version != 2 && $version != 3) {
throw new \RuntimeException('Only supported versions are 2 and 3');
}
self::$version = $version;
}
/**
* Generate a symmetric key for PuTTY v2 keys
*
* @param string $password
* @param int $length
* @return string
*/
private static function generateV2Key($password, $length)
{
$symkey = '';
$sequence = 0;
while (strlen($symkey) < $length) {
$temp = pack('Na*', $sequence++, $password);
$symkey .= Strings::hex2bin(sha1($temp));
}
return substr($symkey, 0, $length);
}
/**
* Generate a symmetric key for PuTTY v3 keys
*
* @param string $password
* @param string $flavour
* @param int $memory
* @param int $passes
* @param string $salt
* @return array
*/
private static function generateV3Key($password, $flavour, $memory, $passes, $salt)
{
if (!function_exists('sodium_crypto_pwhash')) {
throw new \RuntimeException('sodium_crypto_pwhash needs to exist for Argon2 password hasing');
}
switch ($flavour) {
case 'Argon2i':
$flavour = SODIUM_CRYPTO_PWHASH_ALG_ARGON2I13;
break;
case 'Argon2id':
$flavour = SODIUM_CRYPTO_PWHASH_ALG_ARGON2ID13;
break;
default:
throw new UnsupportedAlgorithmException('Only Argon2i and Argon2id are supported');
}
$length = 80; // keylen + ivlen + mac_keylen
$temp = sodium_crypto_pwhash($length, $password, $salt, $passes, $memory << 10, $flavour);
$symkey = substr($temp, 0, 32);
$symiv = substr($temp, 32, 16);
$hashkey = substr($temp, -32);
return compact('symkey', 'symiv', 'hashkey');
}
/**
* Break a public or private key down into its constituent components
*
* @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($key));
}
if (strpos($key, 'BEGIN SSH2 PUBLIC KEY') !== false) {
$lines = preg_split('#[\r\n]+#', $key);
switch (true) {
case $lines[0] != '---- BEGIN SSH2 PUBLIC KEY ----':
throw new \UnexpectedValueException('Key doesn\'t start with ---- BEGIN SSH2 PUBLIC KEY ----');
case $lines[count($lines) - 1] != '---- END SSH2 PUBLIC KEY ----':
throw new \UnexpectedValueException('Key doesn\'t end with ---- END SSH2 PUBLIC KEY ----');
}
$lines = array_splice($lines, 1, -1);
$lines = array_map(function ($line) {
return rtrim($line, "\r\n");
}, $lines);
$data = $current = '';
$values = [];
$in_value = false;
foreach ($lines as $line) {
switch (true) {
case preg_match('#^(.*?): (.*)#', $line, $match):
$in_value = $line[strlen($line) - 1] == '\\';
$current = strtolower($match[1]);
$values[$current] = $in_value ? substr($match[2], 0, -1) : $match[2];
break;
case $in_value:
$in_value = $line[strlen($line) - 1] == '\\';
$values[$current] .= $in_value ? substr($line, 0, -1) : $line;
break;
default:
$data .= $line;
}
}
$components = call_user_func([static::PUBLIC_HANDLER, 'load'], $data);
if ($components === false) {
throw new \UnexpectedValueException('Unable to decode public key');
}
$components += $values;
$components['comment'] = str_replace(['\\\\', '\"'], ['\\', '"'], $values['comment']);
return $components;
}
$components = [];
$key = preg_split('#\r\n|\r|\n#', trim($key));
if (Strings::shift($key[0], strlen('PuTTY-User-Key-File-')) != 'PuTTY-User-Key-File-') {
return false;
}
$version = (int) Strings::shift($key[0], 3); // should be either "2: " or "3: 0" prior to int casting
if ($version != 2 && $version != 3) {
throw new \RuntimeException('Only v2 and v3 PuTTY private keys are supported');
}
$components['type'] = $type = rtrim($key[0]);
if (!in_array($type, static::$types)) {
$error = count(static::$types) == 1 ?
'Only ' . static::$types[0] . ' keys are supported. ' :
'';
throw new UnsupportedAlgorithmException($error . 'This is an unsupported ' . $type . ' key');
}
$encryption = trim(preg_replace('#Encryption: (.+)#', '$1', $key[1]));
$components['comment'] = trim(preg_replace('#Comment: (.+)#', '$1', $key[2]));
$publicLength = trim(preg_replace('#Public-Lines: (\d+)#', '$1', $key[3]));
$public = Strings::base64_decode(implode('', array_map('trim', array_slice($key, 4, $publicLength))));
$source = Strings::packSSH2('ssss', $type, $encryption, $components['comment'], $public);
extract(unpack('Nlength', Strings::shift($public, 4)));
$newtype = Strings::shift($public, $length);
if ($newtype != $type) {
throw new \RuntimeException('The binary type does not match the human readable type field');
}
$components['public'] = $public;
switch ($version) {
case 3:
$hashkey = '';
break;
case 2:
$hashkey = 'putty-private-key-file-mac-key';
}
$offset = $publicLength + 4;
switch ($encryption) {
case 'aes256-cbc':
$crypto = new AES('cbc');
switch ($version) {
case 3:
$flavour = trim(preg_replace('#Key-Derivation: (.*)#', '$1', $key[$offset++]));
$memory = trim(preg_replace('#Argon2-Memory: (\d+)#', '$1', $key[$offset++]));
$passes = trim(preg_replace('#Argon2-Passes: (\d+)#', '$1', $key[$offset++]));
$parallelism = trim(preg_replace('#Argon2-Parallelism: (\d+)#', '$1', $key[$offset++]));
$salt = Strings::hex2bin(trim(preg_replace('#Argon2-Salt: ([0-9a-f]+)#', '$1', $key[$offset++])));
extract(self::generateV3Key($password, $flavour, $memory, $passes, $salt));
break;
case 2:
$symkey = self::generateV2Key($password, 32);
$symiv = str_repeat("\0", $crypto->getBlockLength() >> 3);
$hashkey .= $password;
}
}
switch ($version) {
case 3:
$hash = new Hash('sha256');
$hash->setKey($hashkey);
break;
case 2:
$hash = new Hash('sha1');
$hash->setKey(sha1($hashkey, true));
}
$privateLength = trim(preg_replace('#Private-Lines: (\d+)#', '$1', $key[$offset++]));
$private = Strings::base64_decode(implode('', array_map('trim', array_slice($key, $offset, $privateLength))));
if ($encryption != 'none') {
$crypto->setKey($symkey);
$crypto->setIV($symiv);
$crypto->disablePadding();
$private = $crypto->decrypt($private);
}
$source .= Strings::packSSH2('s', $private);
$hmac = trim(preg_replace('#Private-MAC: (.+)#', '$1', $key[$offset + $privateLength]));
$hmac = Strings::hex2bin($hmac);
if (!hash_equals($hash->hash($source), $hmac)) {
throw new \UnexpectedValueException('MAC validation error');
}
$components['private'] = $private;
return $components;
}
/**
* Wrap a private key appropriately
*
* @param string $public
* @param string $private
* @param string $type
* @param string $password
* @param array $options optional
* @return string
*/
protected static function wrapPrivateKey($public, $private, $type, $password, array $options = [])
{
$encryption = (!empty($password) || is_string($password)) ? 'aes256-cbc' : 'none';
$comment = isset($options['comment']) ? $options['comment'] : self::$comment;
$version = isset($options['version']) ? $options['version'] : self::$version;
$key = "PuTTY-User-Key-File-$version: $type\r\n";
$key .= "Encryption: $encryption\r\n";
$key .= "Comment: $comment\r\n";
$public = Strings::packSSH2('s', $type) . $public;
$source = Strings::packSSH2('ssss', $type, $encryption, $comment, $public);
$public = Strings::base64_encode($public);
$key .= "Public-Lines: " . ((strlen($public) + 63) >> 6) . "\r\n";
$key .= chunk_split($public, 64);
if (empty($password) && !is_string($password)) {
$source .= Strings::packSSH2('s', $private);
switch ($version) {
case 3:
$hash = new Hash('sha256');
$hash->setKey('');
break;
case 2:
$hash = new Hash('sha1');
$hash->setKey(sha1('putty-private-key-file-mac-key', true));
}
} else {
$private .= Random::string(16 - (strlen($private) & 15));
$source .= Strings::packSSH2('s', $private);
$crypto = new AES('cbc');
switch ($version) {
case 3:
$salt = Random::string(16);
$key .= "Key-Derivation: Argon2id\r\n";
$key .= "Argon2-Memory: 8192\r\n";
$key .= "Argon2-Passes: 13\r\n";
$key .= "Argon2-Parallelism: 1\r\n";
$key .= "Argon2-Salt: " . Strings::bin2hex($salt) . "\r\n";
extract(self::generateV3Key($password, 'Argon2id', 8192, 13, $salt));
$hash = new Hash('sha256');
$hash->setKey($hashkey);
break;
case 2:
$symkey = self::generateV2Key($password, 32);
$symiv = str_repeat("\0", $crypto->getBlockLength() >> 3);
$hashkey = 'putty-private-key-file-mac-key' . $password;
$hash = new Hash('sha1');
$hash->setKey(sha1($hashkey, true));
}
$crypto->setKey($symkey);
$crypto->setIV($symiv);
$crypto->disablePadding();
$private = $crypto->encrypt($private);
$mac = $hash->hash($source);
}
$private = Strings::base64_encode($private);
$key .= 'Private-Lines: ' . ((strlen($private) + 63) >> 6) . "\r\n";
$key .= chunk_split($private, 64);
$key .= 'Private-MAC: ' . Strings::bin2hex($hash->hash($source)) . "\r\n";
return $key;
}
/**
* Wrap a public key appropriately
*
* This is basically the format described in RFC 4716 (https://tools.ietf.org/html/rfc4716)
*
* @param string $key
* @param string $type
* @return string
*/
protected static function wrapPublicKey($key, $type)
{
$key = pack('Na*a*', strlen($type), $type, $key);
$key = "---- BEGIN SSH2 PUBLIC KEY ----\r\n" .
'Comment: "' . str_replace(['\\', '"'], ['\\\\', '\"'], self::$comment) . "\"\r\n" .
chunk_split(Strings::base64_encode($key), 64) .
'---- END SSH2 PUBLIC KEY ----';
return $key;
}
}
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