Question

I am using Visual C# built in feature Settings to save some of my program’s options.
I also want to store one password, but then it comes public… is it possible to encrypt the password before saving it using this settings method and then decrypt it back?

Answer 1

For simple encryption needs, I’ve used the DPAPI via the ProtectedData class. To make the resulting encrypted value storable in a text file or registry, I encode the resulting byte array.

Here is the class I wrote to wrap this up:

namespace SomeNamespace
{
   using System;
   using System.Security.Cryptography;
   using System.Text;

   /// <summary>
   /// used for encryption and decryption
   /// </summary>
   public static class DataProtector
   {
      private const string EntropyValue = "secret";

      /// <summary>
      /// Encrypts a string using the DPAPI.
      /// </summary>
      /// <param name="stringToEncrypt">The string to encrypt.</param>
      /// <returns>The encrypted data.</returns>
      public static string EncryptData(string stringToEncrypt)
      {
         byte[] encryptedData = ProtectedData.Protect(Encoding.Unicode.GetBytes(stringToEncrypt), Encoding.Unicode.GetBytes(EntropyValue), DataProtectionScope.LocalMachine);
         return Convert.ToBase64String(encryptedData);
      }

      /// <summary>
      /// Decrypts a string using the DPAPI.
      /// </summary>
      /// <param name="stringToDecrypt">The string to decrypt.</param>
      /// <returns>The decrypted data.</returns>
     public static string DecryptData(string stringToDecrypt)
      {
         byte[] decryptedData = ProtectedData.Unprotect(Convert.FromBase64String(stringToDecrypt), Encoding.Unicode.GetBytes(EntropyValue), DataProtectionScope.LocalMachine);
         return Encoding.Unicode.GetString(decryptedData);
      }
   }
}