+ EGG: bzip2, AZO, LZMA, solid, ZIP/AES/LEA encryption

Compression.Core/Dictionary/Azo/THIRD-PARTY-NOTICE.EggDotNet.txt

@@ -0,0 +1,29 @@
+The AZO decoder (Compression.Core/Dictionary/Azo/AzoDecoder.cs) and the EGG encryption code
+(Hawkynt.FileFormats.Archives/FileFormats/FileFormat.Egg/EggCrypto.cs: ZIP 2.0, AES and LEA variants and
+the LEA block cipher) are converted to C# from EggDotNet; the EGG test archives under
+Compression.Tests/Egg/ReferenceVectors come from its test corpus:
+
+  Upstream: https://github.com/akolman/EggDotNet (master, fetched 2026-10-23)
+  Licence:  MIT
+
+MIT License
+
+Copyright (c) 2026 Andrew Kolman (akolman)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

Compression.Core/README.md

@@ -205,7 +205,7 @@ Use the concrete version you intend to consume; this document does not predict a
 
 <!-- API:BEGIN generated by Hawkynt/RepositoryTemplate/package-readme — edit the XML docs in source, not here -->
 
-Every public and protected member of all 734 types, generated from the built assembly and its XML documentation, is in [REFERENCE.md](https://github.com/Hawkynt/CompressionWorkbench/blob/main/Compression.Core/REFERENCE.md).
+Every public and protected member of all 735 types, generated from the built assembly and its XML documentation, is in [REFERENCE.md](https://github.com/Hawkynt/CompressionWorkbench/blob/main/Compression.Core/REFERENCE.md).
 
 <!-- API:END -->
 

Compression.Core/REFERENCE.md

@@ -636,6 +636,18 @@ Decodes ARJ method 4 ("fastest"), the LZ77 variant ARJ uses when asked for speed
 | --- | --- | --- |
 | `Decode` | `static byte[] Decode(ReadOnlySpan<byte> compressed, int originalSize)` | Decodes `originalSize` bytes of method-4 data. |
 
+### Namespace `Compression.Core.Dictionary.Azo`
+
+[`AzoDecoder`](#azodecoder)
+
+#### `AzoDecoder`
+
+ESTsoft's AZO compression (EGG method 3): independent blocks, each an LZ77 parse coded with an adaptive binary arithmetic coder — literal and length models predicted from context, a distance history, a small dictionary of recent matches.
+
+| Member | Signature | Summary |
+| --- | --- | --- |
+| `Decompress` | `static byte[] Decompress(ReadOnlySpan<byte> data, long expectedSize)` | Decodes an AZO stream into exactly `expectedSize` bytes. |
+
 ### Namespace `Compression.Core.Dictionary.Balz`
 
 [`BalzBuildingBlock`](#balzbuildingblock)

Compression.Tests/Compression.Tests.csproj

@@ -146,6 +146,10 @@
     <EmbeddedResource Include="Zfs\ReferenceVectors\*.gz;Zfs\ReferenceVectors\*.manifest">
       <LogicalName>ZfsVectors.%(Filename)%(Extension)</LogicalName>
     </EmbeddedResource>
+    <!-- EGG archives ALZip wrote, from EggDotNet's test corpus; see Egg/ReferenceVectors/README.md. -->
+    <EmbeddedResource Include="Egg\ReferenceVectors\*.egg">
+      <LogicalName>EggVectors.%(Filename)%(Extension)</LogicalName>
+    </EmbeddedResource>
     <!-- G.722 streams FFmpeg 8.1.2 encoded and decoded; see Codecs/G722/ReferenceVectors/README.md. -->
     <EmbeddedResource Include="Codecs\G722\ReferenceVectors\*.pcm;Codecs\G722\ReferenceVectors\*.g722">
       <LogicalName>G722Vectors.%(Filename)%(Extension)</LogicalName>

Compression.Tests/Egg/EggReferenceTests.cs

@@ -0,0 +1,154 @@
+using System.Reflection;
+using System.Text;
+using FileFormat.Egg;
+
+namespace Compression.Tests.Egg;
+
+/// <summary>
+/// EGG archives ALZip wrote, from EggDotNet's test corpus (MIT). Each data block carries the CRC-32
+/// ALZip computed, which the reader verifies, so a member that decodes is byte-exact; the content
+/// assertions are the ones EggDotNet's own tests make. See ReferenceVectors/README.md.
+/// </summary>
+[TestFixture]
+public class EggReferenceTests {
+  private const string Password = "password12345!";
+
+  private static byte[] Vector(string name) {
+    using var stream = Assembly.GetExecutingAssembly().GetManifestResourceStream($"EggVectors.{name}")
+      ?? throw new FileNotFoundException($"Embedded EGG vector '{name}' is missing from the test assembly.");
+    using var ms = new MemoryStream();
+    stream.CopyTo(ms);
+    return ms.ToArray();
+  }
+
+  private static EggReader Open(string name) => new(new MemoryStream(Vector(name)));
+
+  [TestCase("azoshort_txt.egg", "AZO")]
+  [TestCase("azonumbers.egg", "AZO")]
+  [TestCase("lzma_simple.egg", "LZMA")]
+  [Category("ThirdPartyVector")]
+  public void Given_CompressedMember_When_Extracted_Then_AlZipCrcHolds(string vector, string method) {
+    using var r = Open(vector);
+    var files = r.Entries.Where(e => !e.IsDirectory).ToList();
+    Assert.That(files.Select(e => e.MethodName), Has.Some.EqualTo(method));
+    foreach (var e in files)
+      Assert.That(r.Extract(e), Has.Length.EqualTo(e.UncompressedSize), e.Name);
+  }
+
+  [Test, Category("ThirdPartyVector")]
+  public void Given_LzmaArchive_When_Extracted_Then_SizesMatchEggDotNet() {
+    using var r = Open("lzma_simple.egg");
+    var e = r.Entries.Single(x => x.Name == "lorem_ipsum.txt");
+    Assert.That(e.CompressedSize, Is.EqualTo(5723));
+    Assert.That(r.Extract(e), Has.Length.EqualTo(34446));
+  }
+
+  [TestCase("lorem_long_zipEnc.egg")]
+  [TestCase("lorem_long_aes128.egg")]
+  [TestCase("lorem_long_aes256.egg")]
+  [TestCase("lorem_long_store_lea128.egg")]
+  [TestCase("lorem_long_store_lea256.egg")]
+  [Category("ThirdPartyVector")]
+  public void Given_EncryptedArchive_When_Decrypted_Then_LoremText(string vector) {
+    using var r = Open(vector);
+    var e = r.Entries.Single(x => !x.IsDirectory);
+    Assert.That(e.IsEncrypted, Is.True);
+    var text = Encoding.UTF8.GetString(r.Extract(e, Password));
+    Assert.That(text, Has.Length.EqualTo(15_238));
+    Assert.That(text, Does.StartWith("Lorem ipsum dolor sit amet"));
+    Assert.That(text, Does.EndWith("sed faucibus orci ligula eu nisi."));
+  }
+
+  [TestCase("lorem_long_zipEnc.egg")]
+  [TestCase("lorem_long_aes256.egg")]
+  [TestCase("lorem_long_store_lea128.egg")]
+  [Category("EdgeCase")]
+  public void Given_EncryptedArchive_When_WrongOrNoPassword_Then_Refused(string vector) {
+    using var r = Open(vector);
+    var e = r.Entries.Single(x => !x.IsDirectory);
+    Assert.Throws<InvalidOperationException>(() => r.Extract(e));
+    Assert.Throws<InvalidDataException>(() => r.Extract(e, "badpassword"));
+  }
+
+  [Test, Category("ThirdPartyVector")]
+  public void Given_SolidArchive_When_Extracted_Then_FirstEqualsLast() {
+    using var r = Open("solid.egg");
+    Assert.That(r.IsSolid, Is.True);
+    var files = r.Entries.Where(e => !e.IsDirectory).ToList();
+    Assert.That(r.Extract(files[^1]), Is.EqualTo(r.Extract(files[0])));
+  }
+
+  [TestCase("small_kor.egg", "작은.txt")]
+  [TestCase("small_shift.egg", "小さい.txt")]
+  [Category("ThirdPartyVector")]
+  public void Given_CodePageName_When_Read_Then_DecodedAndHelloWorld(string vector, string name) {
+    System.Text.Encoding.RegisterProvider(System.Text.CodePagesEncodingProvider.Instance);
+    using var r = Open(vector);
+    var e = r.Entries.First();
+    Assert.That(e.Name, Is.EqualTo(name));
+    Assert.That(Encoding.UTF8.GetString(r.Extract(e)), Is.EqualTo("Hello, world!"));
+  }
+
+  [Test, Category("ThirdPartyVector")]
+  public void Given_NestedDirectories_When_Listed_Then_DeepFilePresent() {
+    using var r = Open("directories.egg");
+    Assert.That(r.Entries.Select(e => e.Name), Has.Some.EqualTo("dir1/dir2/dir3/test.txt"));
+  }
+
+  [Test, Category("ThirdPartyVector")]
+  public void Given_LargeMember_When_Listed_Then_SizesMatchEggDotNet() {
+    using var r = Open("zeros.egg");
+    var e = r.Entries.Single();
+    Assert.That(e.CompressedSize, Is.EqualTo(338));
+    Assert.That(e.UncompressedSize, Is.EqualTo(197_540_460));
+  }
+
+  [TestCase("posix_small.egg")]
+  [TestCase("globalcomment.egg")]
+  [Category("ThirdPartyVector")]
+  public void Given_Archive_When_EveryMemberExtracted_Then_CrcHolds(string vector) {
+    using var r = Open(vector);
+    foreach (var e in r.Entries.Where(e => !e.IsDirectory))
+      Assert.That(r.Extract(e), Has.Length.EqualTo(e.UncompressedSize), e.Name);
+  }
+
+  [Test, Category("EdgeCase")]
+  public void Given_CorruptAzoBlock_When_Extracted_Then_InvalidData() {
+    var bytes = Vector("azoshort_txt.egg");
+    using var probe = new EggReader(new MemoryStream(bytes));
+    var e = probe.Entries.Single();
+    bytes[bytes.Length - 20] ^= 0x5A;
+    using var r = new EggReader(new MemoryStream(bytes));
+    Assert.Throws<InvalidDataException>(() => r.Extract(r.Entries.Single()));
+  }
+
+  private static byte[] OursText() =>
+    Encoding.ASCII.GetBytes(string.Concat(Enumerable.Range(0, 300).Select(i => $"EGG line {i % 17}\r\n")));
+
+  private static byte[] OursRaw() => [.. Enumerable.Range(0, 3000).Select(i => (byte)(i * 7))];
+
+  // ours.egg is what our writer produced for these three inputs; EggDotNet read it back
+  // (ReferenceVectors/eggdotnet-listing.txt: both members Deflate, CRC valid, SHA-256 as below).
+  [Test, Category("ThirdPartyVector")]
+  public void Given_SameInputs_When_Written_Then_BytesEqualTheEggDotNetAcceptedFixture() {
+    using var ms = new MemoryStream();
+    new EggFormatDescriptor().Create(ms, [
+      Compression.Registry.ArchiveInputInfo.InMemory("docs/text.txt", OursText()),
+      Compression.Registry.ArchiveInputInfo.InMemory("empty.txt", []),
+      Compression.Registry.ArchiveInputInfo.InMemory("raw.bin", OursRaw()),
+    ], new Compression.Registry.FormatCreateOptions());
+    Assert.That(ms.ToArray(), Is.EqualTo(Vector("ours.egg")));
+  }
+
+  [Test, Category("ThirdPartyVector")]
+  public void Given_OurFixture_When_Read_Then_MatchesEggDotNetListing() {
+    using var r = Open("ours.egg");
+    Assert.That(r.Entries.Select(e => e.Name), Is.EqualTo(new[] { "docs/text.txt", "empty.txt", "raw.bin" }));
+    var text = r.Extract(r.Entries.Single(e => e.Name == "docs/text.txt"));
+    Assert.That(Convert.ToHexStringLower(System.Security.Cryptography.SHA256.HashData(text)),
+      Is.EqualTo("53ff0c178b3267b2dffbdd59979fba67927f8cc7cc60a4eb209b7c06e92096c9"));
+    Assert.That(text, Is.EqualTo(OursText()));
+    Assert.That(r.Extract(r.Entries.Single(e => e.Name == "raw.bin")), Is.EqualTo(OursRaw()));
+    Assert.That(r.Extract(r.Entries.Single(e => e.Name == "empty.txt")), Is.Empty);
+  }
+}

Compression.Tests/Egg/EggTests.cs

@@ -183,14 +183,14 @@ public void Writer_LongUtf8Filename_UsesExtendedExtraFieldLength() {
   [Test, Category("HappyPath")]
   public void UnsupportedMethod_ListsButThrowsOnExtract() {
     var payload = "ignored"u8.ToArray();
-    // Algorithm 4 = LZMA — listed, but extraction must throw rather than fake bytes.
-    var archive = BuildStoreOrRaw("movie.lzma", payload, payload, algorithm: 4);
+    // Algorithm 9 is not an EGG method — listed, but extraction must throw rather than fake bytes.
+    var archive = BuildStoreOrRaw("movie.lzma", payload, payload, algorithm: 9);
 
     var d = new EggFormatDescriptor();
     using var ms = new MemoryStream(archive);
     var entries = d.List(ms, null);
     Assert.That(entries, Has.Count.EqualTo(1));
-    Assert.That(entries[0].Method, Is.EqualTo("LZMA"));
+    Assert.That(entries[0].Method, Is.EqualTo("Method9"));
 
     ms.Position = 0;
     Assert.Throws<NotSupportedException>(() =>

Compression.Tests/Egg/ReferenceVectors/.gitattributes

@@ -0,0 +1,2 @@
+# Fixture bytes are the test: never let a checkout rewrite line endings.
+*.egg -text

Compression.Tests/Egg/ReferenceVectors/README.md

@@ -0,0 +1,24 @@
+# EGG reference vectors
+
+All files come unmodified from EggDotNet's test corpus (`src/EggDotNet.Tests/test_files/`,
+akolman/EggDotNet master, MIT, fetched 2026-10-23); they were written by ALZip.
+
+| File | Exercises |
+| --- | --- |
+| `azoshort_txt.egg`, `azonumbers.egg` | AZO compression |
+| `lzma_simple.egg` | LZMA (34 446 bytes in 5 723) |
+| `solid.egg` | solid mode (first and last member identical) |
+| `lorem_long_zipEnc.egg`, `lorem_long_aes128.egg`, `lorem_long_aes256.egg` | ZIP 2.0, AES-128 and AES-256 encryption (password `password12345!`) |
+| `lorem_long_store_lea128.egg`, `lorem_long_store_lea256.egg` | LEA-128 and LEA-256 encryption (same password) |
+| `small_kor.egg`, `small_shift.egg` | CP949 and Shift-JIS file names |
+| `directories.egg` | nested directories |
+| `zeros.egg` | a 197 540 460-byte member (listed, not extracted) |
+| `posix_small.egg`, `globalcomment.egg` | POSIX file information, archive comment |
+
+Each data block stores the CRC-32 ALZip computed, and the reader checks it, so every member these
+tests extract is byte-exact; the content assertions repeat EggDotNet's own.
+
+`ours.egg` is our writer's output (`docs/text.txt`, an empty `empty.txt`, `raw.bin`; Deflate).
+EggDotNet (same revision, a net10.0 console that opens each member and checks its CRC) read it
+back as recorded in `eggdotnet-listing.txt`. The empty member has no block, as ALZip writes it, so
+EggDotNet lists it without opening it.

Compression.Tests/Egg/ReferenceVectors/eggdotnet-listing.txt

@@ -0,0 +1,3 @@
+ours.egg	docs/text.txt	3720	53ff0c178b3267b2dffbdd59979fba67927f8cc7cc60a4eb209b7c06e92096c9	Deflate	crc=True
+ours.egg	empty.txt	0	(no block)
+ours.egg	raw.bin	3000	7291514d2492fd7ff49e10ba7df95d19d31d199b89d74bcb62cebdee1bc1a498	Deflate	crc=True

Compression.Tests/FirmwareHex/FirmwareHexPayloadTests.cs

@@ -0,0 +1,37 @@
+using Compression.Registry;
+using FileFormat.FirmwareHex;
+
+namespace Compression.Tests.FirmwareHex;
+
+[TestFixture]
+public sealed class FirmwareHexPayloadTests {
+  [TestCase(false)]
+  [TestCase(true)]
+  public void Create_RejectsMultiplePayloadsWithoutWritingOutput(bool emptyFirst) {
+    var descriptor = new IntelHexFormatDescriptor();
+    using var output = new MemoryStream();
+    var inputs = new[] {
+      ArchiveInputInfo.InMemory("first.bin", emptyFirst ? [] : [1, 2, 3]),
+      ArchiveInputInfo.InMemory("second.bin", [9, 8, 7]),
+    };
+
+    Assert.Throws<InvalidDataException>(() =>
+      ((IArchiveCreatable)descriptor).Create(output, inputs, new FormatCreateOptions()));
+    Assert.That(output.Length, Is.Zero);
+  }
+
+  [Test]
+  public void Add_RejectsAnotherPayloadWithoutChangingTheArchive() {
+    var descriptor = new IntelHexFormatDescriptor();
+    using var archive = new MemoryStream();
+    ((IArchiveCreatable)descriptor).Create(archive,
+      [ArchiveInputInfo.InMemory("firmware.bin", [1, 2, 3])], new FormatCreateOptions());
+    var original = archive.ToArray();
+    archive.Position = 0;
+
+    Assert.Throws<InvalidDataException>(() => ((IArchiveModifiable)descriptor).Add(archive,
+      [ArchiveInputInfo.InMemory("ADD.BIN", [9, 8, 7])]));
+    Assert.That(archive.ToArray(), Is.EqualTo(original));
+  }
+
+}