Correctly implement fuzzers for new encryption streams

[alinpahontu2912]

Correctly implement fuzzers fro the new encryption streams: zipcryptostream and winzipaesstream

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[Copilot]

Pull request overview

This PR updates the fuzzers for the new ZIP encryption streams to exercise the actual ZipArchive encryption/decryption paths (ZipCrypto and WinZip AES) rather than constructing the internal crypto streams via reflection.

Changes:

• Replace reflection-based stream construction with ZipArchive.CreateEntry(..., password, ZipEncryptionMethod) + Open/OpenAsync(password) round-trip workflows.
• Add validation that the entry is encrypted and the expected encryption method is recorded, and verify plaintext round-trips correctly (sync + async).
• Add a “wrong password” scenario intended to ensure failures are handled as InvalidDataException (but it currently doesn’t assert failure if no exception is thrown).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/libraries/Fuzzing/DotnetFuzzing/Fuzzers/ZipCryptoStreamFuzzer.cs	Moves from reflected ZipCryptoStream.Create to ZipArchive-based encrypt/decrypt round-trip for ZipCrypto (sync + async).
src/libraries/Fuzzing/DotnetFuzzing/Fuzzers/WinZipAesStreamFuzzer.cs	Moves from reflected WinZipAesStream.Create to ZipArchive-based encrypt/decrypt round-trip for AES128/192/256 (sync + async).

Comments suppressed due to low confidence (2)

src/libraries/Fuzzing/DotnetFuzzing/Fuzzers/ZipCryptoStreamFuzzer.cs:101

• The “wrong password must fail” check currently passes even if decryption succeeds without throwing. Use Assert.Throws so the fuzzer reliably flags regressions where a wrong password is accepted.

        // Decrypting with a wrong password must fail cleanly with InvalidDataException, never crash.
        try
        {
            using Stream stream = readEntry.Open("wrong-password".AsSpan());
            stream.CopyTo(Stream.Null);
        }
        catch (InvalidDataException)
        {
            // Expected: the header password verifier rejects the wrong key.
        }

src/libraries/Fuzzing/DotnetFuzzing/Fuzzers/WinZipAesStreamFuzzer.cs:113

• The “wrong password must fail” check currently passes even if decryption succeeds without throwing. Use Assert.Throws so the fuzzer reliably flags regressions where a wrong password is accepted.

        // Decrypting with a wrong password must fail cleanly with InvalidDataException, never crash.
        try
        {
            using Stream stream = readEntry.Open("wrong-password".AsSpan());
            stream.CopyTo(Stream.Null);
        }
        catch (InvalidDataException)
        {
            // Expected: the AES password verifier / HMAC rejects the wrong key.
        }

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.