105 lines
3.7 KiB
PHP
105 lines
3.7 KiB
PHP
<?php
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require_once dirname(__FILE__).'/openpgp.php';
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require_once 'Crypt/AES.php';
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require_once 'Crypt/TripleDES.php';
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class OpenPGP_Crypt_AES_TripleDES {
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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 $decrypted;
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}
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}
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return NULL; /* If we get here, we failed */
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}
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public static function decryptPacket($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($key);
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$padAmount = $key_block_bytes - (strlen($epacket->data) % $key_block_bytes);
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if($epacket instanceof OpenPGP_IntegrityProtectedDataPacket) {
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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, $key_block_bytes + 2);
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$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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switch($algo) {
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case 2:
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$cipher = new Crypt_TripleDES(CRYPT_DES_MODE_CFB);
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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 7:
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$cipher = new Crypt_AES(CRYPT_AES_MODE_CFB);
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$cipher->setKeyLength(128);
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break;
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case 8:
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$cipher = new Crypt_AES(CRYPT_AES_MODE_CFB);
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$cipher->setKeyLength(192);
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break;
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case 9:
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$cipher = new Crypt_AES(CRYPT_AES_MODE_CFB);
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$cipher->setKeyLength(256);
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break;
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default:
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$cipher = NULL;
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}
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if(!$cipher) return array(NULL, NULL, NULL); // Unsupported cipher
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if(!isset($key_bytes)) $key_bytes = $cipher->key_size;
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if(!isset($key_block_bytes)) $key_block_bytes = $cipher->block_size;
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return array($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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}
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