/// <summary>
/// Store an encrypted key file for user or machine level usage
/// </summary>
/// <param name="scope">Scope</param>
/// <returns>RSA key</returns>
public static RSA RSAFromFile(DataProtectionScope scope)
{
byte[] esp = new byte[] { 69, 155, 31, 254, 7, 18, 99, 187 };
byte[] esl = new byte[] { 101, 5, 79, 221, 48, 42, 26, 123 };
string xmlFile = (scope == DataProtectionScope.CurrentUser ? Path.Combine(System.Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments), "esku_123_abc.bin") :
Path.Combine(System.Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), "eskm_123_abc.bin"));
RSACryptoServiceProvider rsa;
if (File.Exists(xmlFile))
{
byte[] xmlBytes = File.ReadAllBytes(xmlFile);
xmlBytes = CryptoUtility.AesDecryption(xmlBytes, esp, esl);
rsa = new RSACryptoServiceProvider();
RSAKeyExtensions.FromXmlString(rsa, CryptoUtility.UTF8EncodingNoPrefix.GetString(xmlBytes));
}
else
{
rsa = new RSACryptoServiceProvider(4096);
byte[] xmlBytes = CryptoUtility.UTF8EncodingNoPrefix.GetBytes(RSAKeyExtensions.ToXmlString(rsa, true));
xmlBytes = CryptoUtility.AesEncryption(xmlBytes, esp, esl);
File.WriteAllBytes(xmlFile, xmlBytes);
}
return(rsa);
}