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Here you go. I found it somewhere on the internet. Works well for me.
/// <summary>
/// Encrypts a given password and returns the encrypted data
/// as a base64 string.
/// </summary>
/// <param name="plainText">An unencrypted string that needs
/// to be secured.</param>
/// <returns>A base64 encoded string that represents the encrypted
/// binary data.
/// </returns>
/// <remarks>This solution is not really secure as we are
/// keeping strings in memory. If runtime protection is essential,
/// <see cref="SecureString"/> should be used.</remarks>
/// <exception cref="ArgumentNullException">If <paramref name="plainText"/>
/// is a null reference.</exception>
public string Encrypt(string plainText)
{
if (plainText == null) throw new ArgumentNullException("plainText");
//encrypt data
var data = Encoding.Unicode.GetBytes(plainText);
byte[] encrypted = ProtectedData.Protect(data, null, Scope);
//return as base64 string
return Convert.ToBase64String(encrypted);
}
/// <summary>
/// Decrypts a given string.
/// </summary>
/// <param name="cipher">A base64 encoded string that was created
/// through the <see cref="Encrypt(string)"/> or
/// <see cref="Encrypt(SecureString)"/> extension methods.</param>
/// <returns>The decrypted string.</returns>
/// <remarks>Keep in mind that the decrypted string remains in memory
/// and makes your application vulnerable per se. If runtime protection
/// is essential, <see cref="SecureString"/> should be used.</remarks>
/// <exception cref="ArgumentNullException">If <paramref name="cipher"/>
/// is a null reference.</exception>
public string Decrypt(string cipher)
{
if (cipher == null) thrThis question will answer how to encrypt/decrypt: Encrypt and decrypt a string in C#?
You didn't specify a database, but you will want to base-64 encode it, using Convert.toBase64String. For an example you can use: http://www.opinionatedgeek.com/Blog/blogentry=000361/BlogEntry.aspx
You'll then either save it in a varchar or a blob, depending on how long your encrypted message is, but for a password varchar should work.
The examples above will also cover decryption after decoding the base64.
UPDATE:
In actuality you may not need to use base64 encoding, but I found it helpful, in case I wanted to print it, or send it over the web. If the message is long enough it's best to compress it first, then encrypt, as it is harder to use brute-force when the message was already in a binary form, so it would be hard to tell when you successfully broke the encryption.