Merge PR icsharpcode#323: Fix ZipOutputStream.CloseEntry for AES encrypted Stored entries

* Fix ZipOutputStream.CloseEntry() to work for Stored AES encrypted entries
* Add unit tests for AES encrypted zips whose contents are Stored rather than Deflated

Author: Numpsy

src/ICSharpCode.SharpZipLib/Zip/Compression/Streams/DeflaterOutputStream.cs

@@ -414,7 +414,10 @@ protected override void Dispose(bool disposing)
 			}
 		}
 
-		private void GetAuthCodeIfAES()
+		/// <summary>
+		/// Get the Auth code for AES encrypted entries
+		/// </summary>
+		protected void GetAuthCodeIfAES()
 		{
 			if (cryptoTransform_ is ZipAESTransform)
 			{

src/ICSharpCode.SharpZipLib/Zip/ZipOutputStream.cs

@@ -486,6 +486,12 @@ public void CloseEntry()
 					deflater_.Reset();
 				}
 			}
+			else if (curMethod == CompressionMethod.Stored)
+			{
+				// This is done by Finsh() for Deflated entries, but we need to do it
+				// ourselves for Stored ones
+				base.GetAuthCodeIfAES();
+			}
 
 			// Write the AES Authentication Code (a hash of the compressed and encrypted data)
 			if (curEntry.AESKeySize > 0)

test/ICSharpCode.SharpZipLib.Tests/Zip/ZipEncryptionHandling.cs

@@ -19,6 +19,14 @@ public void Aes128Encryption()
 			CreateZipWithEncryptedEntries("foo", 128);
 		}
 
+		[Test]
+		[Category("Encryption")]
+		[Category("Zip")]
+		public void Aes128EncryptionStored()
+		{
+			CreateZipWithEncryptedEntries("foo", 128, CompressionMethod.Stored);
+		}
+
 		[Test]
 		[Category("Encryption")]
 		[Category("Zip")]
@@ -27,6 +35,14 @@ public void Aes256Encryption()
 			CreateZipWithEncryptedEntries("foo", 256);
 		}
 
+		[Test]
+		[Category("Encryption")]
+		[Category("Zip")]
+		public void Aes256EncryptionStored()
+		{
+			CreateZipWithEncryptedEntries("foo", 256, CompressionMethod.Stored);
+		}
+
 		[Test]
 		[Category("Encryption")]
 		[Category("Zip")]
@@ -88,6 +104,47 @@ public void ZipFileAesRead()
 			}
 		}
 
+		/// <summary>
+		/// Test using AES encryption on a file whose contents are Stored rather than deflated
+		/// </summary>
+		[Test]
+		[Category("Encryption")]
+		[Category("Zip")]
+		public void ZipFileStoreAes()
+		{
+			string password = "password";
+
+			using (var memoryStream = new MemoryStream())
+			{
+				// Try to create a zip stream
+				WriteEncryptedZipToStream(memoryStream, password, 256, CompressionMethod.Stored);
+
+				// reset
+				memoryStream.Seek(0, SeekOrigin.Begin);
+
+				// try to read it
+				var zipFile = new ZipFile(memoryStream, leaveOpen: true)
+				{
+					Password = password
+				};
+
+				foreach (ZipEntry entry in zipFile)
+				{
+					if (!entry.IsFile) continue;
+
+					// Should be stored rather than deflated
+					Assert.That(entry.CompressionMethod, Is.EqualTo(CompressionMethod.Stored), "Entry should be stored");
+
+					using (var zis = zipFile.GetInputStream(entry))
+					using (var sr = new StreamReader(zis, Encoding.UTF8))
+					{
+						var content = sr.ReadToEnd();
+						Assert.That(content, Is.EqualTo(DummyDataString), "Decompressed content does not match input data");
+					}
+				}
+			}
+		}
+
 		private static readonly string[] possible7zPaths = new[] {
 			// Check in PATH
 			"7z", "7za",
@@ -135,7 +192,7 @@ public static bool TryGet7zBinPath(out string path7z)
 			return false;
 		}
 
-		public void WriteEncryptedZipToStream(Stream stream, string password, int keySize)
+		public void WriteEncryptedZipToStream(Stream stream, string password, int keySize, CompressionMethod compressionMethod = CompressionMethod.Deflated)
 		{
 			using (var zs = new ZipOutputStream(stream))
 			{
@@ -146,6 +203,7 @@ public void WriteEncryptedZipToStream(Stream stream, string password, int keySiz
 				ZipEntry zipEntry = new ZipEntry("test");
 				zipEntry.AESKeySize = keySize;
 				zipEntry.DateTime = DateTime.Now;
+				zipEntry.CompressionMethod = compressionMethod;
 
 				zs.PutNextEntry(zipEntry);
 
@@ -160,11 +218,11 @@ public void WriteEncryptedZipToStream(Stream stream, string password, int keySiz
 			}
 		}
 
-		public void CreateZipWithEncryptedEntries(string password, int keySize)
+		public void CreateZipWithEncryptedEntries(string password, int keySize, CompressionMethod compressionMethod = CompressionMethod.Deflated)
 		{
 			using (var ms = new MemoryStream())
 			{
-				WriteEncryptedZipToStream(ms, password, keySize);
+				WriteEncryptedZipToStream(ms, password, keySize, compressionMethod);
 
 				if (TryGet7zBinPath(out string path7z))
 				{