' ------------------------ ValidateSignatures ------------------------
''' <summary>
''' Validates all the digital signatures of a given package.</summary>
''' <param name="package">
''' The package for validating digital signatures.</param>
''' <returns>
''' true if all digital signatures are valid; otherwise false if the
''' package is unsigned or any of the signatures are invalid.</returns>
Private Shared Function ValidateSignatures(ByVal package As Package) As Boolean
    If package Is Nothing Then
        Throw New ArgumentNullException("ValidateSignatures(package)")
    End If

    ' Create a PackageDigitalSignatureManager for the given Package.
    Dim dsm As New PackageDigitalSignatureManager(package)

    ' Check to see if the package contains any signatures.
    If Not dsm.IsSigned Then
        Return False
    End If
    ' The package is not signed.
    ' Verify that all signatures are valid.
    Dim result As VerifyResult = dsm.VerifySignatures(False)
    If result <> VerifyResult.Success Then
        Return False
    End If
    ' One or more digital signatures are invalid.
    ' else if (result == VerifyResult.Success)
    ' All signatures are valid.
    Return True
End Function
' end:ValidateSignatures()