[DRAFT][WIP]Add Zip Archives password support by alinpahontu2912 · Pull Request #122093 · dotnet/runtime

alinpahontu2912 · 2025-12-02T14:58:58Z

Fixes #1545

Big Milestones and status:

Read Encrypted Entries (ZipCrypto, WinZip AES)
Create Encrypted Entries (ZipCrypto, Winzip AES)
Update Mode
Add runtime assets for checking compat with WinRar/7zip/WinZip/etc
Security check for Cryptography methods
Final API design

…assword and unprotected

… with cryptography lib

Copilot

Pull request overview

Copilot reviewed 29 out of 29 changed files in this pull request and generated 8 comments.

src/libraries/Common/src/Microsoft/Win32/SafeHandles/SafeX509Handles.Unix.cs

src/libraries/System.IO.Compression/src/System/IO/Compression/ZipBlocks.cs

src/libraries/System.IO.Compression/src/System/IO/Compression/ZipArchiveEntry.cs

src/libraries/System.IO.Compression/src/System/IO/Compression/ZipArchiveEntry.Async.cs

...O.Compression.ZipFile/src/System/IO/Compression/ZipFileExtensions.ZipArchiveEntry.Extract.cs

src/libraries/System.IO.Compression/tests/ZipCryptoStreamWrappedConformanceTests.cs

Copilot

Pull request overview

Copilot reviewed 29 out of 29 changed files in this pull request and generated 1 comment.

src/libraries/System.IO.Compression/src/System/IO/Compression/ZipArchiveEntry.Async.cs

src/libraries/System.IO.Compression/src/System/IO/Compression/WinZipAesStream.cs

bartonjs

General feedback:

Secrets (including an input password) should never be copied to the heap, unless it's utterly impractical.
Secrets (including an input password) should also only minimally be copied around on the stack.
Copied secrets should be cleared.
Avoid having cryptographic keys (HMAC, AES, etc) stored in arrays.

GitHub's current UI is making this change hard to holistically review, and it's marked as draft, so I've only sprinkled in the most important comments.

src/libraries/System.IO.Compression/src/System/IO/Compression/ZipCryptoStream.cs

src/libraries/System.IO.Compression/src/System/IO/Compression/WinZipAesStream.cs

bartonjs · 2026-03-04T22:52:58Z

src/libraries/System.IO.Compression/src/System/IO/Compression/WinZipAesStream.cs

+        private static void XorBytes(Span<byte> dest, ReadOnlySpan<byte> src)
+        {
+            Debug.Assert(dest.Length <= src.Length);
+
+            for (int i = 0; i < dest.Length; i++)
+            {
+                dest[i] ^= src[i];
+            }
+        }


This undoubtedly could be vectorized to go faster, if you expect the operation to generally be bigger than a few bytes. Even just doing something like

Span<ulong> destUL = Marshal.As<byte, ulong>(dest); ReadOnlySpan<ulong> srcUL = Marshal.As<byte, ulong>(src); XorUL(destUL, srcUL); for (int i = destUL.Length * sizeof(ulong); i < dest.Length; i++) { ... }

(Though I think if src/dest isn't QWORD aligned that might do something less happy on ARM?)

Might be premature, but if we want to vectorize this, then approach with something like Vector<byte> might be better.

src/libraries/System.IO.Compression/src/System/IO/Compression/WinZipAesStream.cs

src/libraries/System.IO.Compression.ZipFile/ref/System.IO.Compression.ZipFile.cs

Copilot

Pull request overview

Copilot reviewed 32 out of 32 changed files in this pull request and generated 9 comments.

src/libraries/System.IO.Compression/src/System/IO/Compression/ZipArchiveEntry.cs

src/libraries/System.IO.Compression/src/System/IO/Compression/ZipArchiveEntry.Async.cs

...O.Compression.ZipFile/src/System/IO/Compression/ZipFileExtensions.ZipArchiveEntry.Extract.cs

src/libraries/System.IO.Compression/src/Resources/Strings.resx

src/libraries/System.IO.Compression/src/System/IO/Compression/ZipCryptoStream.cs

src/libraries/System.IO.Compression/src/System/IO/Compression/WinZipAesStream.cs

src/libraries/System.IO.Compression/src/System/IO/Compression/ZipBlocks.cs

…time into zip_password

Copilot

Pull request overview

Copilot reviewed 34 out of 34 changed files in this pull request and generated 16 comments.

src/libraries/System.IO.Compression/src/System/IO/Compression/WinZipAesStream.cs

src/libraries/System.IO.Compression/tests/ZipCryptoStreamWrappedConformanceTests.cs

src/libraries/System.IO.Compression/src/System/IO/Compression/ZipArchiveEntry.cs

...tem.IO.Compression.ZipFile/src/System/IO/Compression/ZipFileExtensions.ZipArchive.Extract.cs

src/libraries/System.IO.Compression.ZipFile/src/System/IO/Compression/ZipFile.Extract.cs

....Compression.ZipFile/src/System/IO/Compression/ZipFileExtensions.ZipArchive.Extract.Async.cs

src/libraries/System.IO.Compression/tests/ZipCryptoStreamConformanceTests.cs

src/libraries/System.IO.Compression/tests/WinZipAesStreamConformanceTests.cs

src/libraries/System.IO.Compression/src/System/IO/Compression/ZipArchiveEntry.Async.cs

Copilot

Pull request overview

Copilot reviewed 34 out of 34 changed files in this pull request and generated 9 comments.

src/libraries/System.IO.Compression/src/System/IO/Compression/ZipArchiveEntry.Async.cs

+        if (string.IsNullOrEmpty(password))
+        {
+            throw new ArgumentNullException(nameof(password), SR.EmptyPassword);
+        }


src/libraries/System.IO.Compression/src/System/IO/Compression/ZipBlocks.cs

+        public WinZipAesExtraField(ushort VendorVersion, byte AesStrength, ushort CompressionMethod)
+        {
+            this.VendorVersion = VendorVersion;
+            this.AesStrength = AesStrength;
+            this.CompressionMethod = CompressionMethod;


src/libraries/System.IO.Compression/src/System/IO/Compression/ZipArchiveEntry.cs

src/libraries/System.IO.Compression/src/System/IO/Compression/ZipArchiveEntry.Async.cs

+                BitFlagValues savedFlags = _generalPurposeBitFlag;
+                EncryptionMethod savedEncryption = Encryption;
+
+                // For AES entries: clear Encryption so WriteLocalFileHeaderAsync doesn't create a new
+                // AES extra field (the original one in _lhUnknownExtraFields will be used).
+                if (savedEncryption is EncryptionMethod.Aes128 or EncryptionMethod.Aes192 or EncryptionMethod.Aes256)
+                {
+                    Encryption = EncryptionMethod.None;
+                }
+
                await WriteLocalFileHeaderAsync(isEmptyFile: _uncompressedSize == 0, forceWrite: true, cancellationToken).ConfigureAwait(false);

+                // Restore original state
+                _generalPurposeBitFlag = savedFlags;
+                Encryption = savedEncryption;


....Compression.ZipFile/src/System/IO/Compression/ZipFileExtensions.ZipArchive.Extract.Async.cs

+    /// <exception cref="PathTooLongException">The specified path, file name, or both exceed the system-defined maximum length.
+    /// For example, on Windows-based platforms, paths must be less than 248 characters, and file names must be less than 260 characters.</exception>
+    /// <exception cref="DirectoryNotFoundException">The specified path is invalid, (for example, it is on an unmapped drive).</exception>
+    /// <exception cref="IOException">An archive entry?s name is zero-length, contains only whitespace, or contains one or more invalid


src/libraries/System.IO.Compression/tests/ZipCryptoStreamConformanceTests.cs

@@ -0,0 +1,106 @@
+// The .NET Foundation licenses this file to you under the MIT license.


src/libraries/System.IO.Compression/src/System/IO/Compression/ZipArchiveEntry.Async.cs

src/libraries/System.IO.Compression/src/System/IO/Compression/ZipArchiveEntry.cs

src/libraries/System.IO.Compression/src/System/IO/Compression/WinZipAesKeyMaterial.cs

+            byte[] encryptionKey = new byte[keySizeBytes];
+            Array.Copy(keyMaterial, offset, encryptionKey, 0, keySizeBytes);
+            offset += keySizeBytes;
+
+            byte[] hmacKey = new byte[keySizeBytes];
+            Array.Copy(keyMaterial, offset, hmacKey, 0, keySizeBytes);
+            offset += keySizeBytes;
+
+            byte[] passwordVerifier = new byte[2];
+            Array.Copy(keyMaterial, offset, passwordVerifier, 0, 2);
+
+            return new WinZipAesKeyMaterial(salt, encryptionKey, hmacKey, passwordVerifier, keySizeBits);


…lyspan

alinpahontu2912 added 22 commits October 20, 2025 15:38

working zipcrypto, hardcoded password

527c698

add tests with multiple entries with same password and entries with p…

255642b

…assword and unprotected

reading/extracting experimentation and tests

968bb60

add enum for encryption and write methods for zipcrypto stream

19cbc8e

allow encryption of entries

0dec737

add more read/write tests for update mode and small refactors

f30fbfb

add default password and encryption method to ziparchive

aac140b

avoid ambigous calls

eb1a460

avoid ambigous calls and fi some nitpicks

0a7c885

recognize aes encrypted files + build fais due to circular dependency…

817165c

… with cryptography lib

fixed some comments

797921d

remove storing password fields

623f238

initial reading of winzip encrypted files

b61b37c

address zipcrypto comments

122f85a

initial writing test works

55c0613

add more tests for winzipaesstream and work on async methods

cc6d30d

Merge remote-tracking branch 'upstream/main' into zip_password

b056780

async methods done, fix ae-1 validation and add more tests

6732696

Solve some comments

8efa772

refactor tests and ci disable local ones

d5bb294

improve winzipaesstream writing by generating larger keystream

0c659fc

update tests, fixed async opening and updated stream positioning

e2b21ff

github-actions bot added the area-System.IO.Compression label Dec 2, 2025

dotnet-policy-service bot assigned alinpahontu2912 Dec 2, 2025

Merge branch 'main' into zip_password

dbcee70

rzikm self-requested a review December 11, 2025 12:22

Merge branch 'main' into zip_password

ff9160b

fix conflict

58d0bb4

Copilot AI review requested due to automatic review settings February 13, 2026 10:30

fix conflict

9a075ed

Copilot started reviewing on behalf of alinpahontu2912 February 13, 2026 10:31 View session

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alinpahontu2912 added 2 commits February 13, 2026 13:14

fix errors

c220b1b

address copilot feedback

733afd4

Copilot AI review requested due to automatic review settings February 16, 2026 11:19

Copilot started reviewing on behalf of alinpahontu2912 February 16, 2026 11:20 View session

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src/libraries/System.IO.Compression/src/System/IO/Compression/ZipArchiveEntry.Async.cs Outdated Show resolved Hide resolved

GrabYourPitchforks reviewed Feb 24, 2026

View reviewed changes

refactor winzipaesstream key derivation material and address comments

da37424

bartonjs requested changes Mar 4, 2026

View reviewed changes

add fuzzing to encryption streams

f954bd9

Copilot AI review requested due to automatic review settings March 5, 2026 11:02

Copilot started reviewing on behalf of alinpahontu2912 March 5, 2026 11:04 View session

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alinpahontu2912 and others added 3 commits March 11, 2026 14:23

Merge branch 'main' into zip_password

e432256

address security feedback and copilot comments

79ceee7

Merge branch 'zip_password' of https://github.com/alinpahontu2912/run…

d7397a6

…time into zip_password

Copilot AI review requested due to automatic review settings March 11, 2026 14:42

Copilot started reviewing on behalf of alinpahontu2912 March 11, 2026 14:43 View session

Copilot AI reviewed Mar 11, 2026

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Merge branch 'dotnet:main' into zip_password

ab0693a

build-analysis bot mentioned this pull request Mar 12, 2026

AOT precompile failed on ios-arm64: 'No space left on device' (exit code 1) #125107

Open

update password checks and fix reflection tests

f6e0b05

Copilot AI review requested due to automatic review settings March 13, 2026 09:32

Copilot started reviewing on behalf of alinpahontu2912 March 13, 2026 09:33 View session

Copilot AI reviewed Mar 13, 2026

View reviewed changes

update string password params to take either readonlymemory or readon…

ac82868

…lyspan

		@@ -0,0 +1,106 @@
		// The .NET Foundation licenses this file to you under the MIT license.

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alinpahontu2912 commented Dec 2, 2025 •

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