243 lines
9.1 KiB
PHP
243 lines
9.1 KiB
PHP
<?php
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use phpseclib3\Crypt\AES as Crypt_AES;
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use phpseclib3\Crypt\Blowfish as Crypt_Blowfish;
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use phpseclib3\Crypt\TripleDES as Crypt_TripleDES;
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use phpseclib3\Crypt\Twofish as Crypt_Twofish;
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use phpseclib3\Crypt\Random;
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require_once dirname(__FILE__).'/openpgp.php';
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@include_once dirname(__FILE__).'/openpgp_crypt_rsa.php';
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@include_once dirname(__FILE__).'/openpgp_mcrypt_wrapper.php';
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@include_once dirname(__FILE__).'/openpgp_openssl_wrapper.php';
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class OpenPGP_Crypt_Symmetric {
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public static function encrypt($passphrases_and_keys, $message, $symmetric_algorithm=9) {
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list($cipher, $key_bytes, $key_block_bytes) = self::getCipher($symmetric_algorithm);
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if(!$cipher) throw new Exception("Unsupported cipher");
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$prefix = Random::string($key_block_bytes);
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$prefix .= substr($prefix, -2);
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$key = Random::string($key_bytes);
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$cipher->setKey($key);
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$to_encrypt = $prefix . $message->to_bytes();
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$mdc = new OpenPGP_ModificationDetectionCodePacket(hash('sha1', $to_encrypt . "\xD3\x14", true));
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$to_encrypt .= $mdc->to_bytes();
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$encrypted = array(new OpenPGP_IntegrityProtectedDataPacket($cipher->encrypt($to_encrypt)));
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if(!is_array($passphrases_and_keys) && !($passphrases_and_keys instanceof IteratorAggregate)) {
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$passphrases_and_keys = (array)$passphrases_and_keys;
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}
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foreach($passphrases_and_keys as $pass) {
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if($pass instanceof OpenPGP_PublicKeyPacket) {
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if(!in_array($pass->algorithm, array(1,2,3))) throw new Exception("Only RSA keys are supported.");
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$crypt_rsa = new OpenPGP_Crypt_RSA($pass);
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$rsa = $crypt_rsa->public_key()->withPadding(CRYPT_RSA_ENCRYPTION_PKCS1 | CRYPT_RSA_SIGNATURE_PKCS1);
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$esk = $rsa->encrypt(chr($symmetric_algorithm) . $key . pack('n', self::checksum($key)));
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$esk = pack('n', OpenPGP::bitlength($esk)) . $esk;
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array_unshift($encrypted, new OpenPGP_AsymmetricSessionKeyPacket($pass->algorithm, $pass->fingerprint(), $esk));
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} else if(is_string($pass)) {
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$s2k = new OpenPGP_S2K(Random::string(8));
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$cipher->setKey($s2k->make_key($pass, $key_bytes));
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$esk = $cipher->encrypt(chr($symmetric_algorithm) . $key);
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array_unshift($encrypted, new OpenPGP_SymmetricSessionKeyPacket($s2k, $esk, $symmetric_algorithm));
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}
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}
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return new OpenPGP_Message($encrypted);
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}
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public static function decryptSymmetric($pass, $m) {
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$epacket = self::getEncryptedData($m);
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foreach($m as $p) {
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if($p instanceof OpenPGP_SymmetricSessionKeyPacket) {
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if(strlen($p->encrypted_data) > 0) {
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list($cipher, $key_bytes, $key_block_bytes) = self::getCipher($p->symmetric_algorithm);
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if(!$cipher) continue;
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$cipher->setKey($p->s2k->make_key($pass, $key_bytes));
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$padAmount = $key_block_bytes - (strlen($p->encrypted_data) % $key_block_bytes);
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$data = substr($cipher->decrypt($p->encrypted_data . str_repeat("\0", $padAmount)), 0, strlen($p->encrypted_data));
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$decrypted = self::decryptPacket($epacket, ord($data[0]), substr($data, 1));
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} else {
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list($cipher, $key_bytes, $key_block_bytes) = self::getCipher($p->symmetric_algorithm);
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$decrypted = self::decryptPacket($epacket, $p->symmetric_algorithm, $p->s2k->make_key($pass, $key_bytes));
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}
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if($decrypted) return $decrypted;
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}
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}
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return NULL; /* If we get here, we failed */
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}
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public static function encryptSecretKey($pass, $packet, $symmetric_algorithm=9) {
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$packet = clone $packet; // Do not mutate original
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$packet->s2k_useage = 254;
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$packet->symmetric_algorithm = $symmetric_algorithm;
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list($cipher, $key_bytes, $key_block_bytes) = self::getCipher($packet->symmetric_algorithm);
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if(!$cipher) throw new Exception("Unsupported cipher");
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$material = '';
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foreach(OpenPGP_SecretKeyPacket::$secret_key_fields[$packet->algorithm] as $field) {
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$f = $packet->key[$field];
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$material .= pack('n', OpenPGP::bitlength($f)) . $f;
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unset($packet->key[$field]);
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}
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$material .= hash('sha1', $material, true);
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$iv = Random::string($key_block_bytes);
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if(!$packet->s2k) $packet->s2k = new OpenPGP_S2K(Random::string(8));
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$cipher->setKey($packet->s2k->make_key($pass, $key_bytes));
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$cipher->setIV($iv);
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$packet->encrypted_data = $iv . $cipher->encrypt($material);
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return $packet;
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}
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public static function decryptSecretKey($pass, $packet) {
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$packet = clone $packet; // Do not mutate orinigal
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list($cipher, $key_bytes, $key_block_bytes) = self::getCipher($packet->symmetric_algorithm);
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if(!$cipher) throw new Exception("Unsupported cipher");
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$cipher->setKey($packet->s2k->make_key($pass, $key_bytes));
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$cipher->setIV(substr($packet->encrypted_data, 0, $key_block_bytes));
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$material = $cipher->decrypt(substr($packet->encrypted_data, $key_block_bytes));
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if($packet->s2k_useage == 254) {
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$chk = substr($material, -20);
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$material = substr($material, 0, -20);
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if($chk != hash('sha1', $material, true)) return NULL;
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} else {
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$chk = unpack('n', substr($material, -2));
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$chk = reset($chk);
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$material = substr($material, 0, -2);
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$mkChk = self::checksum($material);
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if($chk != $mkChk) return NULL;
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}
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$packet->s2k = NULL;
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$packet->s2k_useage = 0;
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$packet->symmetric_algorithm = 0;
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$packet->encrypted_data = NULL;
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$packet->input = $material;
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$packet->key_from_input();
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unset($packet->input);
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return $packet;
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}
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public static function decryptPacket($epacket, $symmetric_algorithm, $key) {
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list($cipher, $key_bytes, $key_block_bytes) = self::getCipher($symmetric_algorithm);
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if(!$cipher) return NULL;
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$cipher->setKey($key);
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if($epacket instanceof OpenPGP_IntegrityProtectedDataPacket) {
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$padAmount = $key_block_bytes - (strlen($epacket->data) % $key_block_bytes);
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$data = substr($cipher->decrypt($epacket->data . str_repeat("\0", $padAmount)), 0, strlen($epacket->data));
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$prefix = substr($data, 0, $key_block_bytes + 2);
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$mdc = substr(substr($data, -22, 22), 2);
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$data = substr($data, $key_block_bytes + 2, -22);
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$mkMDC = hash("sha1", $prefix . $data . "\xD3\x14", true);
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if($mkMDC !== $mdc) return false;
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try {
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$msg = OpenPGP_Message::parse($data);
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} catch (Exception $ex) { $msg = NULL; }
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if($msg) return $msg; /* Otherwise keep trying */
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} else {
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// No MDC mean decrypt with resync
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$iv = substr($epacket->data, 2, $key_block_bytes);
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$edata = substr($epacket->data, $key_block_bytes + 2);
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$padAmount = $key_block_bytes - (strlen($edata) % $key_block_bytes);
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$cipher->setIV($iv);
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$data = substr($cipher->decrypt($edata . str_repeat("\0", $padAmount)), 0, strlen($edata));
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try {
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$msg = OpenPGP_Message::parse($data);
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} catch (Exception $ex) { $msg = NULL; }
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if($msg) return $msg; /* Otherwise keep trying */
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}
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return NULL; /* Failed */
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}
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public static function getCipher($algo) {
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$cipher = NULL;
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// https://datatracker.ietf.org/doc/html/rfc4880#section-13.9
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// " 1. The feedback register (FR) is set to the IV, which is all zeros."
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switch($algo) {
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case NULL:
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case 0:
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throw new Exception("Data is already unencrypted");
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case 2:
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$cipher = new Crypt_TripleDES('cfb');
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$cipher->setIV(str_repeat(pack('x'), 8));
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$key_bytes = 24;
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$key_block_bytes = 8;
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break;
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case 3:
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if(class_exists('OpenSSLWrapper')) {
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$cipher = new OpenSSLWrapper("CAST5-CFB");
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} else if(defined('MCRYPT_CAST_128')) {
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$cipher = new MCryptWrapper(MCRYPT_CAST_128);
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}
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break;
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case 4:
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$cipher = new Crypt_Blowfish('cfb');
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$cipher->setIV(str_repeat(pack('x'), 8));
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$key_bytes = 16;
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$key_block_bytes = 8;
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break;
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case 7:
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$cipher = new Crypt_AES('cfb');
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$cipher->setKeyLength(128);
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$cipher->setIV(str_repeat(pack('x'), 16));
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break;
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case 8:
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$cipher = new Crypt_AES('cfb');
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$cipher->setKeyLength(192);
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$cipher->setIV(str_repeat(pack('x'), 16));
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break;
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case 9:
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$cipher = new Crypt_AES('cfb');
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$cipher->setKeyLength(256);
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$cipher->setIV(str_repeat(pack('x'), 16));
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break;
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case 10:
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$cipher = new Crypt_Twofish('cfb');
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$cipher->setIV(str_repeat(pack('x'), 16));
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$key_bytes = 32;
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break;
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}
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if(!$cipher) return array(NULL, NULL, NULL); // Unsupported cipher
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if(!isset($key_bytes)) $key_bytes = $cipher->getKeyLength() >> 3;
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if(!isset($key_block_bytes)) $key_block_bytes = $cipher->getBlockLengthInBytes();
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return array($cipher, $key_bytes, $key_block_bytes);
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}
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public static function getEncryptedData($m) {
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foreach($m as $p) {
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if($p instanceof OpenPGP_EncryptedDataPacket) return $p;
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}
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throw new Exception("Can only decrypt EncryptedDataPacket");
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}
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public static function checksum($s) {
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$mkChk = 0;
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for($i = 0; $i < strlen($s); $i++) {
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$mkChk = ($mkChk + ord($s[$i])) % 65536;
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}
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return $mkChk;
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}
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}
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