Add archive-level password protection flags for 7z and rar

src/SharpCompress/Archives/AbstractArchive.cs

@@ -161,6 +161,11 @@ public IReader ExtractAllEntries()
     /// </summary>
     public virtual bool IsSolid => false;
 
+    /// <summary>
+    /// Archive is ENCRYPTED (this means the Archive has password-protected files).
+    /// </summary>
+    public virtual bool IsEncrypted => false;
+
     /// <summary>
     /// The archive can find all the parts of the archive needed to fully extract the archive.  This forces the parsing of the entire archive.
     /// </summary>

src/SharpCompress/Archives/Rar/RarArchive.cs

@@ -84,6 +84,8 @@ protected override IReader CreateReaderForSolidExtraction()
 
     public override bool IsSolid => Volumes.First().IsSolidArchive;
 
+    public override bool IsEncrypted => Entries.First(x => !x.IsDirectory).IsEncrypted;
+
     public virtual int MinVersion => Volumes.First().MinVersion;
     public virtual int MaxVersion => Volumes.First().MaxVersion;
 

src/SharpCompress/Archives/SevenZip/SevenZipArchive.cs

@@ -205,6 +205,8 @@ protected override IReader CreateReaderForSolidExtraction() =>
             .GroupBy(x => x.FilePart.Folder)
             .Any(folder => folder.Count() > 1);
 
+    public override bool IsEncrypted => Entries.First(x => !x.IsDirectory).IsEncrypted;
+
     public override long TotalSize =>
         _database?._packSizes.Aggregate(0L, (total, packSize) => total + packSize) ?? 0;
 

tests/SharpCompress.Test/Rar/RarArchiveTests.cs

@@ -633,4 +633,13 @@ public void Rar5_Encrypted_Iterate_Archive() =>
             "Rar5.encrypted_filesOnly.rar",
             "Failure jpg exe Empty тест.txt jpg\\test.jpg exe\\test.exe"
         );
+
+    [Fact]
+    public void Rar_TestEncryptedDetection()
+    {
+        using var passwordProtectedFilesArchive = RarArchive.Open(
+            Path.Combine(TEST_ARCHIVES_PATH, "Rar.encrypted_filesOnly.rar")
+        );
+        Assert.True(passwordProtectedFilesArchive.IsEncrypted);
+    }
 }

tests/SharpCompress.Test/SevenZip/SevenZipArchiveTests.cs

@@ -224,6 +224,15 @@ public void SevenZipArchive_Tar_PathRead()
         );
     }
 
+    [Fact]
+    public void SevenZipArchive_TestEncryptedDetection()
+    {
+        using var passwordProtectedFilesArchive = SevenZipArchive.Open(
+            Path.Combine(TEST_ARCHIVES_PATH, "7Zip.encryptedFiles.7z")
+        );
+        Assert.True(passwordProtectedFilesArchive.IsEncrypted);
+    }
+
     [Fact]
     public void SevenZipArchive_TestSolidDetection()
     {