[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

rzikm

Looks good, some minor nits.

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

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

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

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

Copilot

Pull request overview

Copilot reviewed 29 out of 29 changed files in this pull request and generated no new comments.

Copilot

Pull request overview

Copilot reviewed 29 out of 29 changed files in this pull request and generated 6 comments.

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

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

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

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

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

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

Copilot

Pull request overview

Copilot reviewed 28 out of 28 changed files in this pull request and generated 6 comments.

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

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

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

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

...stem.IO.Compression.ZipFile/src/System/IO/Compression/ZipFileExtensions.ZipArchive.Create.cs

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.

Copilot · 2026-02-16T11:28:00Z

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

+    public async Task<Stream> OpenAsync(string password, EncryptionMethod encryptionMethod, CancellationToken cancellationToken = default)
+    {
+        cancellationToken.ThrowIfCancellationRequested();
+        ThrowIfInvalidArchive();
+        if (string.IsNullOrEmpty(password))
+        {
+            throw new ArgumentNullException(nameof(password), SR.EmptyPassword);
+        }
+
+        switch (_archive.Mode)
+        {
+            case ZipArchiveMode.Read:
+                if (!IsEncrypted)
+                {
+                    throw new InvalidDataException(SR.EntryNotEncrypted);
+                }
+                return await OpenInReadModeAsync(checkOpenable: true, cancellationToken, password.AsMemory()).ConfigureAwait(false);
+            case ZipArchiveMode.Create:
+                return OpenInWriteMode(password, encryptionMethod);
+            case ZipArchiveMode.Update:
+            default:
+                Debug.Assert(_archive.Mode == ZipArchiveMode.Update);
+                if (!IsEncrypted)
+                {
+                    throw new InvalidDataException(SR.EntryNotEncrypted);
+                }
+                return await OpenInUpdateModeAsync(loadExistingContent: true, cancellationToken, password).ConfigureAwait(false);
+        }


OpenAsync(string password, EncryptionMethod encryptionMethod, ...) currently allows Read/Update modes and ignores encryptionMethod, which contradicts the sync Open(string password, EncryptionMethod) behavior (Read throws; Update throws). This can lead to callers thinking they’re controlling encryption when they aren’t. Align the async overload with the sync contract (only Create mode should accept an encryption method; Read/Update should throw the same exceptions as the sync overload).

GrabYourPitchforks · 2026-02-24T01:22:26Z

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

+
+            // Derive keys using PBKDF2
+            int maxPasswordByteCount = Encoding.UTF8.GetMaxByteCount(password.Length);
+            Span<byte> passwordBytes = stackalloc byte[maxPasswordByteCount];


Potential stack overflow if the length of password isn't constrained.

GrabYourPitchforks · 2026-02-24T01:25:32Z

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

+        {
+            int saltSize = GetSaltSize(keySizeBits);
+            int keySizeBytes = keySizeBits / 8;
+            int expectedSize = saltSize + keySizeBytes + keySizeBytes + 2;


Cryptographic code should normally be within a checked block to help avoid edge case misuse.

Can you instead create a shared structure or tuple for all of this? That way you won't have to parse it every time you open a file, and it means you can consolidate all of the validation logic to the initial tuple creation rather than have the logic spread out across lots of different methods: this method, plus WrapWithDecryptionIfNeeded, plus CreateKey.

GrabYourPitchforks · 2026-02-24T01:31:47Z

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

+            }
+
+            // Verify the salt matches
+            Debug.Assert(fileSalt.AsSpan().SequenceEqual(expectedSalt), "Salt mismatch - key material does not match this entry.");


Why Debug.Assert rather than a proper runtime check?

GrabYourPitchforks · 2026-02-24T01:34:38Z

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

+            }
+
+            // Compare the first 10 bytes of the expected hash
+            if (!storedAuth.AsSpan().SequenceEqual(expectedAuth.AsSpan(0, 10)))


This should probably use FixedTimeEquals (https://learn.microsoft.com/en-us/dotnet/api/system.security.cryptography.cryptographicoperations.fixedtimeequals). Consider replacing all uses of SequenceEqual in this class with calls to FixedTimeEquals if appropriate.

GrabYourPitchforks · 2026-02-24T01:38:45Z

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

+
+        private void IncrementCounter()
+        {
+            // WinZip AES treats the entire 16-byte block as a little-endian 128-bit integer


Why not use a proper UInt128 field instead? You can use BinaryPrimitives to convert it to and from a little-endian binary representation.

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

rzikm reviewed Feb 3, 2026

View reviewed changes

address feedback

405e7fa

Copilot AI review requested due to automatic review settings February 4, 2026 10:13

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alinpahontu2912 and others added 2 commits February 5, 2026 11:37

throw when using unsupported aes algorithm on browser

6369631

Merge branch 'dotnet:main' into zip_password

b128663

Copilot AI review requested due to automatic review settings February 6, 2026 12:17

Copilot started reviewing on behalf of alinpahontu2912 February 6, 2026 12:18 View session

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build-analysis bot mentioned this pull request Feb 6, 2026

Tests failing on tvos with "The app 'net.dot.System.Runtime.Tests' terminated with signal 11" #124072

Open

alinpahontu2912 and others added 2 commits February 9, 2026 09:36

Merge branch 'main' into zip_password

bc358c3

address copilot feedback

91aa400

Copilot AI review requested due to automatic review settings February 9, 2026 13:24

Copilot started reviewing on behalf of alinpahontu2912 February 9, 2026 13:25 View session

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This was referenced Feb 9, 2026

Checkout failure: "Git fetch failed with exit code 128" dotnet/arcade#9009

Open

Unable to checkout dotnet/dnceng#4115

Open

alinpahontu2912 added 2 commits February 11, 2026 13:38

add missing overloads and fix copilot feedback

369a85e

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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GrabYourPitchforks reviewed Feb 24, 2026

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alinpahontu2912 commented Dec 2, 2025 •

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