(VB.NET) Determine if a Zip is Encrypted or Password-Protected

Determines whether or not a zip archive is AES encrypted or password-protected.

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' This example requires the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

Dim zip As New Chilkat.Zip

' An encrypted or password-protected zip can be opened
' without specifying the password.  However, the contents
' of the files cannot be unzipped without providing the correct
' password.

Dim success As Boolean = zip.OpenZip("something.zip")
If (success <> True) Then
    Debug.WriteLine(zip.LastErrorText)
    Exit Sub
End If


' If the zip is password-protected, meaning that it uses
' the old (insecure) Zip 2.0 encryption, then the
' PasswordProtect property will be True
Dim bPwdProt As Boolean = zip.PasswordProtect
If (bPwdProt) Then
    Debug.WriteLine("This zip is password-protected.")
End If


' If the zip is AES encrypted (WinZip compatible) then
' the Encryption property will be equal to 4.
Dim encValue As Integer = zip.Encryption
If (encValue = 4) Then
    Debug.WriteLine("This zip is AES encrypted.")
End If


' If the Encryption property = 0, then the zip is NOT
' strong encrypted, and is either password-protected or
' entirely unencrypted, depending on the value of the
' PasswordProtect property.


zip.CloseZip()