Symmetric encryption/decryption routine using AES

The following is a symmetric encryption/decryption routine using AES in GCM mode. This code operates in the application layer and is meant to receive user-specific and confidential information and encrypt it, after which it is stored in a separate database server. It also is called upon to decrypt encrypted information from the database.

The full description of the AES in GCM mode can be found in this document produced by David A. McGrew and John Viega The Galois/Counter Mode of Operation (GCM)


Database Layer

The DatabaseLayer is an abstraction for database access which means the calling application or library does not need to be tight-coupled to the database itself. A set of factory methods is available to call in order to create commands and parameters, all based on the .NET abstract base classes.

Currently supported engines are SQL server and MySQL, represented by “sql” and “mysql” in your web.config or app.config.

The DatabaseLayer does not use a provider pattern but the argument is passed in the factory to tell the library what database engine to use. An example is shown below. It is preferable to create one constant for the database type and share it across multiple places it is used.

The example below is lazy loaded and uses AppSettings and ConnectionStrings from the web.config or app.config file.

private static Database database;

internal static Database GetDb()
if ( database == null )
database = Database.GetDatabase(
return database;

DatabaseLayer solution