Merge pull request #5 from xp-framework/feature/aes

Implement support for reading AES-enrypted entries

Author: thekid

src/main/php/io/archive/zip/AESInputStream.class.php

@@ -0,0 +1,119 @@
+<?php namespace io\archive\zip;
+
+use io\streams\InputStream;
+use lang\IllegalStateException;
+
+/**
+ * Deciphers using little-endian variant of AES-CTR
+ *
+ * @ext   openssl
+ */
+class AESInputStream implements InputStream {
+  const BLOCK= 16;
+
+  private $in, $key;
+  private $cipher, $counter, $hmac;
+  private $buffer= '';
+
+  /**
+   * Constructor
+   *
+   * @param  io.streams.InputStream $in
+   * @param  string $key
+   * @param  string $auth
+   */
+  public function __construct($in, $key, $auth) {
+    $this->in= $in;
+    $this->key= $key;
+
+    $this->cipher= 'aes-'.(strlen($key) * 8).'-ecb';
+    $this->counter= "\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00";
+    $this->hmac= hash_init('sha1', HASH_HMAC, $auth);
+  }
+
+  /**
+   * Decrypt, updating the HMAC and the counter while doing so
+   *
+   * @param  string $input
+   * @return string
+   */
+  private function decrypt($input) {
+    hash_update($this->hmac, $input);
+
+    $return= '';
+    for ($offset= 0, $l= strlen($input); $offset < $l; $offset+= self::BLOCK) {
+
+      // Encrypt counter block using AES-ECB
+      $keystream= openssl_encrypt(
+        $this->counter,
+        $this->cipher,
+        $this->key,
+        OPENSSL_RAW_DATA | OPENSSL_ZERO_PADDING
+      );
+
+      // Take relevant part
+      $return.= substr($input, $offset, self::BLOCK) ^ $keystream;
+
+      // Increment little-endian counter
+      for ($j= 0, $carry= 1; $j < 16 && $carry; $j++) {
+        $s= ord($this->counter[$j]) + $carry;
+        $this->counter[$j]= chr($s & 0xff);
+        $carry= $s >> 8;
+      }
+    }
+    return $return;
+  }
+
+  /**
+   * Read a string
+   *
+   * @param  int $limit default 8192
+   * @return string
+   * @throws lang.IllegalStateException when HMAC verification fails
+   */
+  public function read($limit= 8192) {
+    $chunk= $this->buffer.$this->in->read($limit);
+
+    // Ensure we always decrypt complete blocks while streaming
+    if ($this->in->available()) {
+      $rest= -strlen($chunk) % self::BLOCK;
+      if ($rest) {
+        $this->buffer= substr($chunk, $rest);
+        return $this->decrypt(substr($chunk, 0, $rest));
+      } else {
+        $this->buffer= '';
+        return $this->decrypt($chunk);
+      }
+    }
+
+    // Verify HMAC checksum for last block
+    $this->buffer= '';
+    $plain= $this->decrypt(substr($chunk, 0, -10));
+
+    $mac= hash_final($this->hmac, true);
+    if (0 !== substr_compare($mac, substr($chunk, -10), 0, 10)) {
+      throw new IllegalStateException('HMAC verification failed — corrupted data');
+    }
+
+    return $plain;
+  }
+
+  /**
+   * Returns the number of bytes that can be read from this stream 
+   * without blocking.
+   * 
+   * @return int
+   */
+  public function available() {
+    return $this->in->available();
+  }
+
+  /**
+   * Close this buffer
+   *
+   * @return void
+   */
+  public function close() {
+    $this->in->close();
+  }
+}

src/main/php/io/archive/zip/AbstractZipReaderImpl.class.php

@@ -1,8 +1,8 @@
 <?php namespace io\archive\zip;
 
 use io\streams\InputStream;
-use lang\{FormatException, IllegalArgumentException};
-use util\Date;
+use lang\{FormatException, IllegalArgumentException, IllegalAccessException};
+use util\{Date, Secret};
 
 /**
  * Abstract base class for zip reader implementations
@@ -34,14 +34,13 @@ public function __construct(InputStream $stream) {
   /**
    * Set password to use when extracting 
    *
-   * @param   string password
+   * @param  ?string|util.Secret $password
    */
   public function setPassword($password) {
     if (null === $password) {
       $this->password= null;
     } else {
-      $this->password= new ZipCipher();
-      $this->password->initialize(iconv(\xp::ENCODING, 'cp437', $password));
+      $this->password= $password instanceof Secret ? $password : new Secret($password);
     }
   }
 
@@ -210,36 +209,65 @@ public function currentEntry() {
           if (!isset($this->index[$name])) throw new FormatException('.zip archive broken: cannot find "'.$name.'" in central directory.');
           $header= $this->index[$name];
 
-          // In case we're here, we can be sure to have a 
-          // RandomAccessStream - otherwise the central directory
-          // could not have been read in the first place. So,
-          // we may seek.
-          // If we had strict type checking this would not be
-          // possible, though.
+          // In case we're here, we can be sure to have a RandomAccessStream - otherwise the
+          // central directory could not have been read in the first place. So, we may seek.
           // The offset is relative to the file begin - but also skip over the usual parts:
           // * file header signature (4 bytes)
           // * file header (26 bytes)
           // * file extra + file name (variable size)
-          $this->streamPosition($header['offset']+ 30 + $header['extralen'] + $header['namelen']);
+          $this->streamPosition($header['offset'] + 30 + $header['extralen'] + $header['namelen']);
 
           // Set skip accordingly: 4 bytes data descriptor signature + 12 bytes data descriptor
-          $this->skip= $header['compressed']+ 16;
+          $this->skip= $header['compressed'] + 16;
         }
 
-        // Bit 1: The file is encrypted
-        if ($header['flags'] & 1) {
-          $cipher= new ZipCipher($this->password);
+        // AES vs. traditional PKZIP cipher
+        if (99 === $header['compression']) {
+          if (null === $this->password) {
+            throw new IllegalAccessException('No password set');
+          }
+
+          $aes= unpack('vheader/vsize/vversion/a2vendor/cstrength/vcompression', $extra);
+          switch ($aes['strength']) {
+            case 1: $sl= 8; $dl= 16; break;
+            case 2: $sl= 12; $dl= 24; break;
+            case 3: $sl= 16; $dl= 32; break;
+            default: throw new IllegalArgumentException('Invalid AES strength '.$aes['strength']);
+          }
+
+          // Verify password
+          $salt= $this->streamRead($sl);
+          $pvv= $this->streamRead(2);
+          $dk= hash_pbkdf2('sha1', $this->password->reveal(), $salt, 1000, 2 * $dl + 2, true);
+          if (0 !== substr_compare($dk, $pvv, 2 * $dl, 2)) {
+            throw new IllegalAccessException('The password did not match');
+          }
+
+          $this->skip-= $sl + 2;
+          $header['compression']= $aes['compression'];
+          $is= new AESInputStream(
+            new ZipFileInputStream($this, $this->position, $header['compressed'] - $sl - 2),
+            substr($dk, 0, $dl),
+            substr($dk, $dl, $dl)
+          );
+        } else if ($header['flags'] & 1) {
+          if (null === $this->password) {
+            throw new IllegalAccessException('No password set');
+          }
+
+          // Verify password
+          $cipher= new ZipCipher();
+          $cipher->initialize(iconv(\xp::ENCODING, 'cp437', $this->password->reveal()));
           $preamble= $cipher->decipher($this->streamRead(12));
-          
-          // Verify            
-          if (ord($preamble[11]) !== (($header['crc'] >> 24) & 0xFF)) {
-            throw new IllegalArgumentException('The password did not match ('.ord($preamble[11]).' vs. '.(($header['crc'] >> 24) & 0xFF).')');
+          if (ord($preamble[11]) !== (($header['crc'] >> 24) & 0xff)) {
+            throw new IllegalAccessException('The password did not match');
           }
 
-          // Password matches.
-          $this->skip-= 12; 
-          $header['compressed']-= 12;
-          $is= new DecipheringInputStream(new ZipFileInputStream($this, $this->position, $header['compressed']), $cipher);
+          $this->skip-= 12;
+          $is= new DecipheringInputStream(
+            new ZipFileInputStream($this, $this->position, $header['compressed'] - 12),
+            $cipher
+          );
         } else {
           $is= new ZipFileInputStream($this, $this->position, $header['compressed']);
         }

src/main/php/io/archive/zip/ZipArchiveWriter.class.php

@@ -2,7 +2,7 @@
 
 use io\streams\OutputStream;
 use lang\{Closeable, IllegalArgumentException};
-use util\Date;
+use util\{Date, Secret};
 
 /**
  * Writes to a ZIP archive
@@ -52,15 +52,19 @@ public function usingUnicodeNames($unicode= true) {
   /**
    * Set password to use when adding entries 
    *
-   * @param   string password
+   * @param   string|util.Secret $password
    * @return  io.archive.zip.ZipArchiveWriter this
    */
   public function usingPassword($password) {
     if (null === $password) {
       $this->password= null;
     } else {
       $this->password= new ZipCipher();
-      $this->password->initialize(iconv(\xp::ENCODING, 'cp437', $password));
+      $this->password->initialize(iconv(
+        \xp::ENCODING,
+        'cp437',
+        $password instanceof Secret ? $password->reveal() : $password)
+      );
     }
     return $this;
   }

src/main/php/io/archive/zip/ZipFileInputStream.class.php

@@ -1,12 +1,13 @@
 <?php namespace io\archive\zip;
 
 use io\IOException;
+use io\streams\InputStream;
 
 /**
  * Zip File input stream. Reads from the current position up until a
  * certain length.
  */
-class ZipFileInputStream implements \io\streams\InputStream {
+class ZipFileInputStream implements InputStream {
   protected 
     $reader      = null,
     $start       = 0,

src/test/php/io/archive/zip/unittest/AbstractZipFileTest.class.php

@@ -3,6 +3,7 @@
 use io\archive\zip\{ZipArchiveReader, ZipEntry, ZipFile};
 use io\streams\Streams;
 use test\verify\Runtime;
+use util\Secret;
 
 /**
  * Base class for testing zip files
@@ -13,6 +14,12 @@
 #[Runtime(extensions: ['zlib'])]
 abstract class AbstractZipFileTest {
 
+  /** @return iterable */
+  private function passwords() {
+    yield ['secret'];
+    yield [new Secret('secret')];
+  }
+
   /**
    * Returns entry content; or NULL for directories
    *

src/test/php/io/archive/zip/unittest/ZipArchiveWriterTest.class.php

@@ -3,7 +3,7 @@
 use io\archive\zip\{ZipArchiveWriter, ZipDirEntry, ZipFile, ZipFileEntry};
 use io\streams\{MemoryInputStream, MemoryOutputStream, StreamTransfer};
 use lang\IllegalArgumentException;
-use test\{Assert, Expect, Test};
+use test\{Assert, Expect, Test, Values};
 
 class ZipArchiveWriterTest extends AbstractZipFileTest {
 
@@ -83,11 +83,11 @@ public function adding_files_and_dir() {
     );
   }
 
-  #[Test]
-  public function using_password_protection() {
+  #[Test, Values(from: 'passwords')]
+  public function using_password_protection($password) {
     $out= new MemoryOutputStream();
 
-    $fixture= ZipFile::create($out)->usingPassword('secret');
+    $fixture= ZipFile::create($out)->usingPassword($password);
     $fixture->addFile(new ZipFileEntry('test.txt'))->out()->write('File contents');
     $fixture->close();
 

src/test/php/io/archive/zip/unittest/vendors/SevenZipFileTest.class.php

@@ -1,8 +1,9 @@
 <?php namespace io\archive\zip\unittest\vendors;
 
 use io\streams\Streams;
+use lang\IllegalAccessException;
 use test\verify\Runtime;
-use test\{Assert, Ignore, Test};
+use test\{Assert, Ignore, Expect, Test, Values};
 
 /**
  * Tests 7-ZIP archives
@@ -57,13 +58,19 @@ public function ppmd() {
     $this->assertCompressedEntryIn($this->archiveReaderFor($this->vendor(), 'ppmd'));
   }
 
-  /**
-   * Assertion helper
-   *
-   * @param   io.archive.zip.ZipArchiveReader reader
-   * @throws  unittest.AssertionFailedError
-   */
-  protected function assertSecuredEntriesIn($reader) {
+  #[Test, Expect(IllegalAccessException::class), Values(['zip-crypto', 'aes-128', 'aes-192', 'aes-256'])]
+  public function missing_password($fixture) {
+    $this->archiveReaderFor($this->vendor(), $fixture)->iterator()->next();
+  }
+
+  #[Test, Expect(IllegalAccessException::class), Values(['zip-crypto', 'aes-128', 'aes-192', 'aes-256'])]
+  public function incorrect_password($fixture) {
+    $this->archiveReaderFor($this->vendor(), $fixture)->usingPassword('wrong')->iterator()->next();
+  }
+
+  #[Test, Values(['zip-crypto', 'aes-128', 'aes-192', 'aes-256'])]
+  public function password_protected($fixture) {
+    $reader= $this->archiveReaderFor($this->vendor(), $fixture);
     with ($it= $reader->usingPassword('secret')->iterator()); {
       $entry= $it->next();
       Assert::equals('password.txt', $entry->getName());
@@ -76,14 +83,4 @@ protected function assertSecuredEntriesIn($reader) {
       Assert::equals('Very secret contents', (string)Streams::readAll($entry->in()));
     }
   }
-
-  #[Test]
-  public function zipCryptoPasswordProtected() {
-    $this->assertSecuredEntriesIn($this->archiveReaderFor($this->vendor(), 'zip-crypto'));
-  }
-
-  #[Test, Ignore('Not yet supported')]
-  public function aes256PasswordProtected() {
-    $this->assertSecuredEntriesIn($this->archiveReaderFor($this->vendor(), 'aes-256'));
-  }
 }