Support AES encryption in FastZip.CreateZip

Author: Numpsy

src/ICSharpCode.SharpZipLib/Zip/FastZip.cs

@@ -226,6 +226,15 @@ public string Password
 			set { password_ = value; }
 		}
 
+		/// <summary>
+		/// Get / set the method of encrypting entries.
+		/// </summary>
+		/// <remarks>
+		/// Only applies when <see cref="Password"/> is set.
+		/// Defaults to ZipCrypto for backwards compatibility purposes.
+		/// </remarks>
+		public ZipEncryptionMethod EntryEncryptionMethod { get; set; } = ZipEncryptionMethod.ZipCrypto;
+
 		/// <summary>
 		/// Get or set the <see cref="INameTransform"></see> active when creating Zip files.
 		/// </summary>
@@ -369,7 +378,7 @@ public void CreateZip(Stream outputStream, string sourceDirectory, bool recurse,
 			{
 				outputStream_.SetLevel((int)CompressionLevel);
 
-				if (password_ != null)
+				if (false == string.IsNullOrEmpty(password_) && EntryEncryptionMethod != ZipEncryptionMethod.None)
 				{
 					outputStream_.Password = password_;
 				}
@@ -539,6 +548,10 @@ private void ProcessFile(object sender, ScanEventArgs e)
 					using (FileStream stream = File.Open(e.Name, FileMode.Open, FileAccess.Read, FileShare.Read))
 					{
 						ZipEntry entry = entryFactory_.MakeFileEntry(e.Name);
+
+						// Set up AES encryption for the entry if required.
+						ConfigureEntryEncryption(entry);
+
 						outputStream_.PutNextEntry(entry);
 						AddFileContents(e.Name, stream);
 					}
@@ -558,6 +571,26 @@ private void ProcessFile(object sender, ScanEventArgs e)
 			}
 		}
 
+		// Set up the encryption method to use for the specific entry.
+		private void ConfigureEntryEncryption(ZipEntry entry)
+		{
+			// Only alter the entries options if AES isn't already enabled for it
+			// (it might have been set up by the entry factory, and if so we let that take precedence)
+			if (!string.IsNullOrEmpty(Password) && entry.AESEncryptionStrength == 0)
+			{
+				switch (EntryEncryptionMethod)
+				{
+					case ZipEncryptionMethod.AES128:
+						entry.AESKeySize = 128;
+						break;
+
+					case ZipEncryptionMethod.AES256:
+						entry.AESKeySize = 256;
+						break;
+				}
+			}
+		}
+
 		private void AddFileContents(string name, Stream stream)
 		{
 			if (stream == null)

src/ICSharpCode.SharpZipLib/Zip/ZipEncryptionMethod.cs

@@ -0,0 +1,28 @@
+namespace ICSharpCode.SharpZipLib.Zip
+{
+	/// <summary>
+	/// The method of encrypting entries when creating zip archives.
+	/// </summary>
+	public enum ZipEncryptionMethod
+	{
+		/// <summary>
+		/// No encryption will be used.
+		/// </summary>
+		None,
+
+		/// <summary>
+		/// Encrypt entries with ZipCrypto.
+		/// </summary>
+		ZipCrypto,
+
+		/// <summary>
+		/// Encrypt entries with AES 128.
+		/// </summary>
+		AES128,
+
+		/// <summary>
+		/// Encrypt entries with AES 256.
+		/// </summary>
+		AES256
+	}
+}

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

@@ -159,8 +159,11 @@ public void ContentEqualAfterAfterArchived([Values(0, 1, 64)]int contentSize)
 		}
 
 		[Test]
+		[TestCase(ZipEncryptionMethod.ZipCrypto)]
+		[TestCase(ZipEncryptionMethod.AES128)]
+		[TestCase(ZipEncryptionMethod.AES256)]
 		[Category("Zip")]
-		public void Encryption()
+		public void Encryption(ZipEncryptionMethod encryptionMethod)
 		{
 			const string tempName1 = "a.dat";
 
@@ -174,8 +177,11 @@ public void Encryption()
 
 			try
 			{
-				var fastZip = new FastZip();
-				fastZip.Password = "Ahoy";
+				var fastZip = new FastZip
+				{
+					Password = "Ahoy",
+					EntryEncryptionMethod = encryptionMethod
+				};
 
 				fastZip.CreateZip(target, tempFilePath, false, @"a\.dat", null);
 
@@ -189,6 +195,21 @@ public void Encryption()
 					Assert.AreEqual(1, entry.Size);
 					Assert.IsTrue(zf.TestArchive(true));
 					Assert.IsTrue(entry.IsCrypted);
+
+					switch (encryptionMethod)
+					{
+						case ZipEncryptionMethod.ZipCrypto:
+							Assert.That(entry.AESKeySize, Is.Zero, "AES key size should be 0 for ZipCrypto encrypted entries");
+							break;
+
+						case ZipEncryptionMethod.AES128:
+							Assert.That(entry.AESKeySize, Is.EqualTo(128), "AES key size should be 128 for AES128 encrypted entries");
+							break;
+
+						case ZipEncryptionMethod.AES256:
+							Assert.That(entry.AESKeySize, Is.EqualTo(256), "AES key size should be 256 for AES256 encrypted entries");
+							break;
+					}
 				}
 			}
 			finally