Encrypting Configuration Information in ASP.NET 2.0 Applications

When creating ASP.NET 2.0 applications, developers commonly store sensitive configuration information in the Web.configfile. The cannonical example is database connection strings, but other sensitive information included in the Web.configfile can include SMTP server connection information and user credentials, among others. While ASP.NET is configured, by default, to reject all HTTP requests to resources with the .config extension, the sensitive information in Web.configcan be compromised if a hacker obtains access to your web server's file system. For example, perhaps you forgot to disallow anonymous FTP access to your website, thereby allowing a hacker to simply FTP in and download your Web.config file. Eep.
Fortunately ASP.NET 2.0 helps mitigate this problem by allowing selective portions of the Web.config file to be encrypted, such as the <connectionStrings> section, or some custom config section used by your application. Configuration sections can be easily encrypted using code or aspnet_regiis.exe, a command-line program. Once encrypted, the Web.config settings are safe from prying eyes. Furthermore, when retrieving encrypted congifuration settings programmatically in your ASP.NET pages, ASP.NET will automatically decrypt the encrypted sections its reading. In short, once the configuration information in encrypted, you don't need to write any further code or take any further action to use that encrypted data in your application.
In this article we'll see how to programmatically encrypt and decrypt portions of the configuration settings and look at using the aspnet_regiis.exe command-line program. We'll then evaluate the encryption options ASP.NET 2.0 offers. There's also a short discussion on how to encrypt configuration information in ASP.NET version 1.x. Read on to learn more!
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