Indexing on Encrypted Columns

1) We have SQL Server 2005 database on Windows 2003 Server.
2) Some columns data of some tables are encrypted while inserting itself with help of encryption views (datatype - varbinary).
3) We select data from tables using decryption views.
4) We use symmetric key & certificate for encryption and decryption respectively.
5) For normal columns we can index on tables but for encryption/decryption data columns, will indexes on tables on raw data columns of tables work or on views on their columns which represent normal data.
6) Our stored procedures have select queries only on decryption views but index tuning advisor is throwing indexes & statistics on tables even for encrypted columns.