<?php use phpseclib\Crypt\TripleDES as Crypt_TripleDES; use phpseclib\Crypt\AES as Crypt_AES; use phpseclib\Crypt\Random; define('CRYPT_DES_MODE_CFB', Crypt_TripleDES::MODE_CFB); define('CRYPT_AES_MODE_CFB', Crypt_AES::MODE_CFB); require_once dirname(__FILE__).'/openpgp.php'; @include_once dirname(__FILE__).'/openpgp_crypt_rsa.php'; @include_once dirname(__FILE__).'/openpgp_mcrypt_wrapper.php'; class OpenPGP_Crypt_Symmetric { public static function encrypt($passphrases_and_keys, $message, $symmetric_algorithm=9) { list($cipher, $key_bytes, $key_block_bytes) = self::getCipher($symmetric_algorithm); if(!$cipher) throw new Exception("Unsupported cipher"); $prefix = Random::string($key_block_bytes); $prefix .= substr($prefix, -2); $key = Random::string($key_bytes); $cipher->setKey($key); $to_encrypt = $prefix . $message->to_bytes(); $mdc = new OpenPGP_ModificationDetectionCodePacket(hash('sha1', $to_encrypt . "\xD3\x14", true)); $to_encrypt .= $mdc->to_bytes(); $encrypted = array(new OpenPGP_IntegrityProtectedDataPacket($cipher->encrypt($to_encrypt))); if(!is_array($passphrases_and_keys) && !($passphrases_and_keys instanceof IteratorAggregate)) { $passphrases_and_keys = (array)$passphrases_and_keys; } foreach($passphrases_and_keys as $pass) { if($pass instanceof OpenPGP_PublicKeyPacket) { if(!in_array($pass->algorithm, array(1,2,3))) throw new Exception("Only RSA keys are supported."); $crypt_rsa = new OpenPGP_Crypt_RSA($pass); $rsa = $crypt_rsa->public_key(); $rsa->setEncryptionMode(CRYPT_RSA_ENCRYPTION_PKCS1); $esk = $rsa->encrypt(chr($symmetric_algorithm) . $key . pack('n', self::checksum($key))); $esk = pack('n', OpenPGP::bitlength($esk)) . $esk; array_unshift($encrypted, new OpenPGP_AsymmetricSessionKeyPacket($pass->algorithm, $pass->fingerprint(), $esk)); } else if(is_string($pass)) { $s2k = new OpenPGP_S2K(Random::string(10)); $cipher->setKey($s2k->make_key($pass, $key_bytes)); $esk = $cipher->encrypt(chr($symmetric_algorithm) . $key); array_unshift($encrypted, new OpenPGP_SymmetricSessionKeyPacket($s2k, $esk, $symmetric_algorithm)); } } return new OpenPGP_Message($encrypted); } public static function decryptSymmetric($pass, $m) { $epacket = self::getEncryptedData($m); foreach($m as $p) { if($p instanceof OpenPGP_SymmetricSessionKeyPacket) { if(strlen($p->encrypted_data) > 0) { list($cipher, $key_bytes, $key_block_bytes) = self::getCipher($p->symmetric_algorithm); if(!$cipher) continue; $cipher->setKey($p->s2k->make_key($pass, $key_bytes)); $padAmount = $key_block_bytes - (strlen($p->encrypted_data) % $key_block_bytes); $data = substr($cipher->decrypt($p->encrypted_data . str_repeat("\0", $padAmount)), 0, strlen($p->encrypted_data)); $decrypted = self::decryptPacket($epacket, ord($data{0}), substr($data, 1)); } else { list($cipher, $key_bytes, $key_block_bytes) = self::getCipher($p->symmetric_algorithm); $decrypted = self::decryptPacket($epacket, $p->symmetric_algorithm, $p->s2k->make_key($pass, $key_bytes)); } if($decrypted) return $decrypted; } } return NULL; /* If we get here, we failed */ } public static function decryptSecretKey($pass, $packet) { $packet = clone $packet; // Do not mutate orinigal list($cipher, $key_bytes, $key_block_bytes) = self::getCipher($packet->symmetric_algorithm); if(!$cipher) throw new Exception("Unsupported cipher"); $cipher->setKey($packet->s2k->make_key($pass, $key_bytes)); $cipher->setIV(substr($packet->encrypted_data, 0, $key_block_bytes)); $material = $cipher->decrypt(substr($packet->encrypted_data, $key_block_bytes)); if($packet->s2k_useage == 254) { $chk = substr($material, -20); $material = substr($material, 0, -20); if($chk != hash('sha1', $material, true)) return NULL; } else { $chk = unpack('n', substr($material, -2)); $chk = reset($chk); $material = substr($material, 0, -2); $mkChk = self::checksum($material); if($chk != $mkChk) return NULL; } $packet->s2k_useage = 0; $packet->symmetric_algorithm = 0; $packet->encrypted_data = NULL; $packet->input = $material; $packet->key_from_input(); unset($packet->input); return $packet; } public static function decryptPacket($epacket, $symmetric_algorithm, $key) { list($cipher, $key_bytes, $key_block_bytes) = self::getCipher($symmetric_algorithm); if(!$cipher) return NULL; $cipher->setKey($key); if($epacket instanceof OpenPGP_IntegrityProtectedDataPacket) { $padAmount = $key_block_bytes - (strlen($epacket->data) % $key_block_bytes); $data = substr($cipher->decrypt($epacket->data . str_repeat("\0", $padAmount)), 0, strlen($epacket->data)); $prefix = substr($data, 0, $key_block_bytes + 2); $mdc = substr(substr($data, -22, 22), 2); $data = substr($data, $key_block_bytes + 2, -22); $mkMDC = hash("sha1", $prefix . $data . "\xD3\x14", true); if($mkMDC !== $mdc) return false; try { $msg = OpenPGP_Message::parse($data); } catch (Exception $ex) { $msg = NULL; } if($msg) return $msg; /* Otherwise keep trying */ } else { // No MDC mean decrypt with resync $iv = substr($epacket->data, 2, $key_block_bytes); $edata = substr($epacket->data, $key_block_bytes + 2); $padAmount = $key_block_bytes - (strlen($edata) % $key_block_bytes); $cipher->setIV($iv); $data = substr($cipher->decrypt($edata . str_repeat("\0", $padAmount)), 0, strlen($edata)); try { $msg = OpenPGP_Message::parse($data); } catch (Exception $ex) { $msg = NULL; } if($msg) return $msg; /* Otherwise keep trying */ } return NULL; /* Failed */ } public static function getCipher($algo) { $cipher = NULL; switch($algo) { case 2: $cipher = new Crypt_TripleDES(CRYPT_DES_MODE_CFB); $key_bytes = 24; $key_block_bytes = 8; break; case 3: if(defined('MCRYPT_CAST_128')) { $cipher = new MCryptWrapper(MCRYPT_CAST_128); } else { throw new Exception("Unsupported cipher: you must have mcrypt installed to use CAST5"); } break; case 7: $cipher = new Crypt_AES(CRYPT_AES_MODE_CFB); $cipher->setKeyLength(128); break; case 8: $cipher = new Crypt_AES(CRYPT_AES_MODE_CFB); $cipher->setKeyLength(192); break; case 9: $cipher = new Crypt_AES(CRYPT_AES_MODE_CFB); $cipher->setKeyLength(256); break; } if(!$cipher) return array(NULL, NULL, NULL); // Unsupported cipher if(!isset($key_bytes)) $key_bytes = isset($cipher->key_size)?$cipher->key_size:$cipher->key_length; if(!isset($key_block_bytes)) $key_block_bytes = $cipher->block_size; return array($cipher, $key_bytes, $key_block_bytes); } public static function getEncryptedData($m) { foreach($m as $p) { if($p instanceof OpenPGP_EncryptedDataPacket) return $p; } throw new Exception("Can only decrypt EncryptedDataPacket"); } public static function checksum($s) { $mkChk = 0; for($i = 0; $i < strlen($s); $i++) { $mkChk = ($mkChk + ord($s{$i})) % 65536; } return $mkChk; } }