/// <summary>
/// Load protected data as strings from file. Call this function in your production environment, loading in a securely encrypted file which will stay encrypted in memory.
/// </summary>
/// <param name="path">Path to load from</param>
/// <returns>Protected data</returns>
public static SecureString[] LoadProtectedStringsFromFile(string path)
{
byte[] bytes = File.ReadAllBytes(path);
// while unprotectedBytes is populated, app is vulnerable - we clear this array ASAP to remove sensitive data from memory
byte[] unprotectedBytes = DataProtector.Unprotect(bytes);
MemoryStream memory = new MemoryStream(unprotectedBytes);
BinaryReader reader = new BinaryReader(memory, Encoding.UTF8);
SecureString current;
int len;
List <SecureString> strings = new List <SecureString>();
while (memory.Position != memory.Length)
{
// copy char by char into secure string to avoid making additional string copies of sensitive data
current = new SecureString();
strings.Add(current);
len = reader.ReadInt32();
while (len-- > 0)
{
current.AppendChar(reader.ReadChar());
}
}
// cleanup and zero it out, hopefully GC hasn't moved unprotectedBytes around in memory
Array.Clear(bytes, 0, bytes.Length);
Array.Clear(unprotectedBytes, 0, unprotectedBytes.Length);
return(strings.ToArray());
}
/// <summary>
/// Save unprotected data as strings to a file, where it will be encrypted for the current user account. Call this method offline with the data you need to secure.
/// Call CryptoUtility.LoadProtectedStringsFromFile to later load these strings from the file.
/// </summary>
/// <param name="path">Path to save to</param>
/// <param name="strings">Strings to save.</param>
/// <example><![CDATA[
/// CryptoUtility.SaveUnprotectedStringsToFile("test.bin", new string[] { "my super secret user name", "my super secret password with a ❤heart" });
/// SecureString[] secure = CryptoUtility.LoadProtectedStringsFromFile("test.bin");
/// string s;
/// for (int i = 0; i<secure.Length; i++)
/// {
/// s = CryptoUtility.SecureStringToString(secure[i]);
/// Console.WriteLine(s);
/// }
/// Console.ReadLine();
/// ]]></example>
public static void SaveUnprotectedStringsToFile(string path, string[] strings)
{
MemoryStream memory = new MemoryStream();
BinaryWriter writer = new BinaryWriter(memory, Encoding.UTF8);
char[] chars;
foreach (string s in strings)
{
chars = s.ToArray();
writer.Write(chars.Length);
foreach (char c in chars)
{
writer.Write(c);
}
}
writer.Flush();
File.WriteAllBytes(path, DataProtector.Protect(memory.ToArray()));
}
