Merge pull request #3 from Slamdunk/tag_final

Mark stream end to detect file truncation

Author: Slamdunk

infection.json.dist

@@ -34,7 +34,7 @@
         },
         "UnwrapSubstr": {
             "ignoreSourceCodeByRegex": [
-                ".+ = substr\\(\\$this->buffer,( 0,)? self::(EN|DE)CRYPT_READ_BYTES\\);"
+                ".+ = substr\\(\\$this->buffer,( 0,)? \\$(read|write)ChunkSize\\);"
             ]
         }
     },

psalm-baseline.xml

@@ -23,5 +23,8 @@
       <code>EncryptorStreamFilterTest</code>
       <code>EncryptorStreamFilterTest</code>
     </PropertyNotSetInConstructor>
+    <UnusedFunctionCall occurrences="1">
+      <code>stream_get_contents</code>
+    </UnusedFunctionCall>
   </file>
 </files>

src/EncryptorStreamFilter.php

@@ -5,6 +5,7 @@
 namespace SlamCompressAndEncryptProxy;
 
 use php_user_filter;
+use RuntimeException;
 
 /**
  * @internal
@@ -14,8 +15,7 @@ final class EncryptorStreamFilter extends php_user_filter
     private const FILTERNAME_PREFIX = 'slamflysystemencryptor';
     private const MODE_ENCRYPT = '.encrypt';
     private const MODE_DECRYPT = '.decrypt';
-    private const ENCRYPT_READ_BYTES = 8175;
-    private const DECRYPT_READ_BYTES = 8192;
+    private const CHUNK_SIZE = 8192;
 
     private ?string $key;
     private string $mode;
@@ -117,11 +117,21 @@ private function encryptFilter($out, &$consumed, $closing): int
             \assert(\is_string($header));
         }
 
-        while (self::ENCRYPT_READ_BYTES <= \strlen($this->buffer) || $closing) {
-            $data = substr($this->buffer, 0, self::ENCRYPT_READ_BYTES);
-            $this->buffer = substr($this->buffer, self::ENCRYPT_READ_BYTES);
+        $readChunkSize = self::CHUNK_SIZE - SODIUM_CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_ABYTES;
+        while ($readChunkSize <= \strlen($this->buffer) || $closing) {
+            $data = substr($this->buffer, 0, $readChunkSize);
+            $this->buffer = substr($this->buffer, $readChunkSize);
 
-            $newBucketData = $header.sodium_crypto_secretstream_xchacha20poly1305_push($this->state, $data);
+            $tag = SODIUM_CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_TAG_MESSAGE;
+            if ($closing && '' === $this->buffer) {
+                $tag = SODIUM_CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_TAG_FINAL;
+            }
+            $newBucketData = $header.sodium_crypto_secretstream_xchacha20poly1305_push(
+                $this->state,
+                $data,
+                '',
+                $tag
+            );
 
             \assert(\is_resource($this->stream));
             $newBucket = stream_bucket_new(
@@ -158,13 +168,21 @@ private function decryptFilter($out, &$consumed, $closing): int
             sodium_memzero($this->key);
         }
 
-        while (self::DECRYPT_READ_BYTES <= \strlen($this->buffer) || $closing) {
-            $data = substr($this->buffer, 0, self::DECRYPT_READ_BYTES);
-            $this->buffer = substr($this->buffer, self::DECRYPT_READ_BYTES);
+        $writeChunkSize = self::CHUNK_SIZE;
+        while ($writeChunkSize <= \strlen($this->buffer) || $closing) {
+            $data = substr($this->buffer, 0, $writeChunkSize);
+            $this->buffer = substr($this->buffer, $writeChunkSize);
 
-            [$newBucketData] = sodium_crypto_secretstream_xchacha20poly1305_pull($this->state, $data);
+            $expectedTag = SODIUM_CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_TAG_MESSAGE;
+            if ($closing && '' === $this->buffer) {
+                $expectedTag = SODIUM_CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_TAG_FINAL;
+            }
+            [$newBucketData, $tag] = sodium_crypto_secretstream_xchacha20poly1305_pull($this->state, $data);
             \assert(\is_string($newBucketData));
 
+            if ($expectedTag !== $tag) {
+                throw new RuntimeException('Encrypted stream corrupted');
+            }
             \assert(\is_resource($this->stream));
             $newBucket = stream_bucket_new(
                 $this->stream,

test/CompressAndEncryptAdapterTest.php

@@ -198,15 +198,22 @@ public function writing_a_file_writes_a_compressed_and_encrypted_file(): void
     public function regression(): void
     {
         $key = 'RjWFkMrJS4Jd5TDdhYJNAWdfSEL5nptu4KQHgkeKGI0=';
-        $content = base64_decode('IZS+uLwIi3vfk+/txrq+7V7vQ0GGN9cwWetC8p/IRMstNUFfxB363Dt1jwxM7LbK3M4EX4earQ==', true);
-
+        $originalPlain = 'foobar';
         $adapter = new CompressAndEncryptAdapter(
             new LocalFilesystemAdapter($this->remoteMock),
             $key
         );
+
+        // To recreate assets, uncomment following lines
+        // $adapter->write('/file.txt', $originalPlain, new Config());
+        // var_dump(
+        //     base64_encode(file_get_contents($this->remoteMock.'/file.txt'.CompressAndEncryptAdapter::REMOTE_FILE_EXTENSION))
+        // ); exit;
+
+        $content = base64_decode('Zp1CKRNAdEebRInjHnuJwuG1gI2owWedBVboddwd+sW4AKv/3a112UjHnlpJntUUZgPBStuSFw==', true);
         file_put_contents($this->remoteMock.'/file.txt'.CompressAndEncryptAdapter::REMOTE_FILE_EXTENSION, $content);
 
-        static::assertSame('foobar', $adapter->read('/file.txt'));
+        static::assertSame($originalPlain, $adapter->read('/file.txt'));
     }
 
     /**

test/EncryptorStreamFilterTest.php

@@ -5,6 +5,7 @@
 namespace SlamCompressAndEncryptProxy\Test;
 
 use PHPUnit\Framework\TestCase;
+use RuntimeException;
 use SlamCompressAndEncryptProxy\EncryptorStreamFilter;
 
 /**
@@ -62,6 +63,36 @@ public function provideCases(): array
         ];
     }
 
+    /**
+     * @test
+     */
+    public function detect_file_corruption(): void
+    {
+        $key = sodium_crypto_secretstream_xchacha20poly1305_keygen();
+        EncryptorStreamFilter::register();
+
+        $chunkSize = 8192;
+        $originalPlain = random_bytes(10 * ($chunkSize - SODIUM_CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_ABYTES));
+
+        $cipherStream = $this->streamFromContents($originalPlain);
+        EncryptorStreamFilter::appendEncryption($cipherStream, $key);
+
+        $cipher = stream_get_contents($cipherStream);
+        fclose($cipherStream);
+        static::assertNotSame($originalPlain, $cipher);
+        static::assertSame(
+            (10 * $chunkSize) + SODIUM_CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_HEADERBYTES,
+            \strlen($cipher)
+        );
+
+        $truncatedCipher = substr($cipher, 0, (9 * $chunkSize) + SODIUM_CRYPTO_SECRETSTREAM_XCHACHA20POLY1305_HEADERBYTES);
+        $plainStream = $this->streamFromContents($truncatedCipher);
+        EncryptorStreamFilter::appendDecryption($plainStream, $key);
+
+        $this->expectException(RuntimeException::class);
+        stream_get_contents($plainStream);
+    }
+
     /**
      * @test
      */
@@ -104,18 +135,26 @@ public function consecutive_filtering(): void
     public function regression(): void
     {
         $key = base64_decode('Z+Ry4nDufKcJ19pU2pEMgGiac9GBWFjEV18Cpb9jxRM=', true);
-        $cipher = base64_decode('PMRzbW/xSj1WPnXp0DknCZvmM1Lv1XCYNbQH5wHozLpULVaGnoq7kVOuhg5Guew=', true);
-
+        $originalPlain = 'foobar';
         EncryptorStreamFilter::register();
 
+        // To recreate assets, uncomment following lines
+        // $cipherStream = $this->streamFromContents($content);
+        // EncryptorStreamFilter::appendEncryption($cipherStream, $key);
+        // $cipher = stream_get_contents($cipherStream);
+        // fclose($cipherStream);
+        // var_dump(base64_encode($cipher)); exit;
+
+        $cipher = base64_decode('UbQpWpd03RyW8a2YiVQSlkmfeEN76IgkN67yPRb7UoXcxUeL7LmUGizXL7zwbtc=', true);
+
         $plainStream = $this->streamFromContents($cipher);
         EncryptorStreamFilter::appendDecryption($plainStream, $key);
 
         $plain = stream_get_contents($plainStream);
 
         fclose($plainStream);
 
-        static::assertSame('foobar', $plain);
+        static::assertSame($originalPlain, $plain);
     }
 
     /**