mirror of
https://github.com/Ne-Lexa/php-zip.git
synced 2025-10-23 11:06:12 +02:00
Completely rewritten code.
Implement read-only zip file - class \PhpZip\ZipFile, create and update zip file - \PhpZip\ZipOutputFile. Supports ZIP64 ext, Traditional PKWARE Encryption, WinZip AES Encryption.
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Ne-Lexa
231
src/PhpZip/Crypto/WinZipAesEngine.php
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231
src/PhpZip/Crypto/WinZipAesEngine.php
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<?php
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namespace PhpZip\Crypto;
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use PhpZip\Exception\ZipAuthenticationException;
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use PhpZip\Exception\ZipCryptoException;
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use PhpZip\Extra\WinZipAesEntryExtraField;
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use PhpZip\Model\ZipEntry;
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use PhpZip\Util\CryptoUtil;
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/**
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* WinZip Aes Encryption Engine.
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*
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* @author Ne-Lexa alexey@nelexa.ru
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* @license MIT
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*/
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class WinZipAesEngine
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{
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/**
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* The block size of the Advanced Encryption Specification (AES) Algorithm
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* in bits (AES_BLOCK_SIZE_BITS).
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*/
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const AES_BLOCK_SIZE_BITS = 128;
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const PWD_VERIFIER_BITS = 16;
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/**
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* The iteration count for the derived keys of the cipher, KLAC and MAC.
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*/
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const ITERATION_COUNT = 1000;
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/**
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* @var ZipEntry
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*/
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private $entry;
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/**
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* WinZipAesEngine constructor.
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* @param ZipEntry $entry
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*/
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public function __construct(ZipEntry $entry)
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{
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$this->entry = $entry;
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}
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/**
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* Decrypt from stream resource.
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*
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* @param resource $stream Input stream resource
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* @return string
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* @throws ZipAuthenticationException
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* @throws ZipCryptoException
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*/
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public function decrypt($stream)
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{
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/**
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* @var WinZipAesEntryExtraField $field
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*/
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$field = $this->entry->getExtraField(WinZipAesEntryExtraField::getHeaderId());
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if (null === $field) {
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throw new ZipCryptoException($this->entry->getName() . " (missing extra field for WinZip AES entry)");
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}
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$pos = ftell($stream);
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// Get key strength.
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$keyStrengthBits = $field->getKeyStrength();
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$keyStrengthBytes = $keyStrengthBits / 8;
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$salt = fread($stream, $keyStrengthBytes / 2);
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$passwordVerifier = fread($stream, self::PWD_VERIFIER_BITS / 8);
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$sha1Size = 20;
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// Init start, end and size of encrypted data.
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$endPos = $pos + $this->entry->getCompressedSize();
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$start = ftell($stream);
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$footerSize = $sha1Size / 2;
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$end = $endPos - $footerSize;
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$size = $end - $start;
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if (0 > $size) {
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throw new ZipCryptoException($this->entry->getName() . " (false positive WinZip AES entry is too short)");
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}
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// Load authentication code.
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fseek($stream, $end, SEEK_SET);
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$authenticationCode = fread($stream, $footerSize);
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if (ftell($stream) !== $endPos) {
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// This should never happen unless someone is writing to the
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// end of the file concurrently!
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throw new ZipCryptoException("Expected end of file after WinZip AES authentication code!");
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}
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do {
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assert($this->entry->getPassword() !== null);
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assert(self::AES_BLOCK_SIZE_BITS <= $keyStrengthBits);
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// Here comes the strange part about WinZip AES encryption:
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// Its unorthodox use of the Password-Based Key Derivation
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// Function 2 (PBKDF2) of PKCS #5 V2.0 alias RFC 2898.
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// Yes, the password verifier is only a 16 bit value.
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// So we must use the MAC for password verification, too.
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$keyParam = hash_pbkdf2("sha1", $this->entry->getPassword(), $salt, self::ITERATION_COUNT, (2 * $keyStrengthBits + self::PWD_VERIFIER_BITS) / 8, true);
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$ctrIvSize = self::AES_BLOCK_SIZE_BITS / 8;
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$iv = str_repeat(chr(0), $ctrIvSize);
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$key = substr($keyParam, 0, $keyStrengthBytes);
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$sha1MacParam = substr($keyParam, $keyStrengthBytes, $keyStrengthBytes);
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// Verify password.
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} while (!$passwordVerifier === substr($keyParam, 2 * $keyStrengthBytes));
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$content = stream_get_contents($stream, $size, $start);
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$mac = hash_hmac('sha1', $content, $sha1MacParam, true);
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if ($authenticationCode !== substr($mac, 0, 10)) {
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throw new ZipAuthenticationException($this->entry->getName() . " (authenticated WinZip AES entry content has been tampered with)");
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}
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return self::aesCtrSegmentIntegerCounter(false, $content, $key, $iv);
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}
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/**
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* Decryption or encryption AES-CTR with Segment Integer Count (SIC).
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*
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* @param bool $encrypted If true encryption else decryption
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* @param string $str Data
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* @param string $key Key
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* @param string $iv IV
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* @return string
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*/
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private static function aesCtrSegmentIntegerCounter($encrypted = true, $str, $key, $iv)
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{
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$numOfBlocks = ceil(strlen($str) / 16);
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$ctrStr = '';
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for ($i = 0; $i < $numOfBlocks; ++$i) {
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for ($j = 0; $j < 16; ++$j) {
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$n = ord($iv[$j]);
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if (++$n === 0x100) {
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// overflow, set this one to 0, increment next
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$iv[$j] = chr(0);
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} else {
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// no overflow, just write incremented number back and abort
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$iv[$j] = chr($n);
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break;
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}
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}
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$data = substr($str, $i * 16, 16);
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$ctrStr .= $encrypted ?
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self::encryptCtr($data, $key, $iv) :
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self::decryptCtr($data, $key, $iv);
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}
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return $ctrStr;
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}
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/**
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* Encrypt AES-CTR.
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*
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* @param string $data Raw data
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* @param string $key Aes key
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* @param string $iv Aes IV
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* @return string Encrypted data
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*/
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private static function encryptCtr($data, $key, $iv)
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{
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if (extension_loaded("openssl")) {
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$numBits = strlen($key) * 8;
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return openssl_encrypt($data, 'AES-' . $numBits . '-CTR', $key, OPENSSL_RAW_DATA, $iv);
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} elseif (extension_loaded("mcrypt")) {
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return mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $key, $data, "ctr", $iv);
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} else {
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throw new \RuntimeException('Extension openssl or mcrypt not loaded');
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}
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}
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/**
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* Decrypt AES-CTR.
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*
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* @param string $data Encrypted data
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* @param string $key Aes key
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* @param string $iv Aes IV
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* @return string Raw data
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*/
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private static function decryptCtr($data, $key, $iv)
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{
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if (extension_loaded("openssl")) {
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$numBits = strlen($key) * 8;
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return openssl_decrypt($data, 'AES-' . $numBits . '-CTR', $key, OPENSSL_RAW_DATA, $iv);
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} elseif (extension_loaded("mcrypt")) {
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return mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key, $data, "ctr", $iv);
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} else {
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throw new \RuntimeException('Extension openssl or mcrypt not loaded');
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}
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}
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/**
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* Encryption string.
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*
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* @param string $content
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* @return string
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*/
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public function encrypt($content)
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{
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// Init key strength.
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$password = $this->entry->getPassword();
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assert($password !== null);
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$keyStrengthBytes = 32;
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$keyStrengthBits = $keyStrengthBytes * 8;
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assert(self::AES_BLOCK_SIZE_BITS <= $keyStrengthBits);
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$salt = CryptoUtil::randomBytes($keyStrengthBytes / 2);
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$keyParam = hash_pbkdf2("sha1", $password, $salt, self::ITERATION_COUNT, (2 * $keyStrengthBits + self::PWD_VERIFIER_BITS) / 8, true);
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$sha1HMacParam = substr($keyParam, $keyStrengthBytes, $keyStrengthBytes);
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// Can you believe they "forgot" the nonce in the CTR mode IV?! :-(
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$ctrIvSize = self::AES_BLOCK_SIZE_BITS / 8;
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$iv = str_repeat(chr(0), $ctrIvSize);
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$key = substr($keyParam, 0, $keyStrengthBytes);
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$content = self::aesCtrSegmentIntegerCounter(true, $content, $key, $iv);
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$mac = hash_hmac('sha1', $content, $sha1HMacParam, true);
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return ($salt .
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substr($keyParam, 2 * $keyStrengthBytes, self::PWD_VERIFIER_BITS / 8) .
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$content .
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substr($mac, 0, 10)
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);
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}
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}
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