This tutorial article with source code shows how to encrypt a password, save to a disk file, and use it to authenticate a user.

You can encrypt a password using the .NET Cryptography and Text namespaces.

Included in the free downloadable source code is a class named EncryptPassword. This class contains a method named 'EncryptString' that uses the Text namespace's UnicodeEncoding method to convert a string passed into the class into a Byte array, encrypts the string using the Cryptography namespace's MD5CryptoServiceProvider and returns the encrypted string to the caller.

In the Windows Forms example provided in the source code are two methods.

The first, 'EncryptAndSave', takes a password entered by a user, encrypts it with the EncryptPassword class, then saves the encrypted password to file.

The second, 'ValidatePassword', takes a password entered by a user, encrypts it with the EncryptPassword class, retrieves a encrypted password from file, and validates that the password provided by the user matches the password stored to file.

Click the link above to download Visual Basic source code in a Visual Studio solution which demonstrates how to use the Cryptography and Text namespaces to encrypt a password.

NOTE: The source code was created with Visual Basic 2002. To use it with Visual Basic 2003, open it with Visual Studio 2003 and just say yes when asked if you want to convert it.