Reads and decrypts CMS enveloped-data object using the recipient's private key.
public static int ReadEnvDataToFile( string outputFile, string inputFile, string x509File, string privateKey, Cms.Options options )
Public Shared Function ReadEnvDataToFile ( _ outputFile As String, _ inputFile As String, _ x509File As String, _ privateKey As String, _ options As Cms.Options _ ) As Integer
Zero if successful; otherwise it returns an error code