[c#] Convert String to SecureString

How to convert String to SecureString?

You can follow this:

string password = "test";
SecureString sec_pass = new SecureString();
Array.ForEach(password.ToArray(), sec_pass.AppendChar);
sec_pass.MakeReadOnly();

If you would like to compress the conversion of a string to a SecureString into a LINQ statement you can express it as follows:

var plain  = "The quick brown fox jumps over the lazy dog";
var secure = plain
             .ToCharArray()
             .Aggregate( new SecureString()
                       , (s, c) => { s.AppendChar(c); return s; }
                       , (s)    => { s.MakeReadOnly(); return s; }
                       );

However, keep in mind that using LINQ does not improve the security of this solution. It suffers from the same flaw as any conversion from string to SecureString. As long as the original string remains in memory the data is vulnerable.

That being said, what the above statement can offer is keeping together the creation of the SecureString, its initialization with data and finally locking it from modification.

unsafe 
{
    fixed(char* psz = password)
        return new SecureString(psz, password.Length);
}

below method helps to convert string to secure string

private SecureString ConvertToSecureString(string password)
{
    if (password == null)
        throw new ArgumentNullException("password");

    var securePassword = new SecureString();

    foreach (char c in password)
        securePassword.AppendChar(c);

    securePassword.MakeReadOnly();
    return securePassword;
}

I'm agree with Spence (+1), but if you're doing it for learning or testing pourposes, you can use a foreach in the string, appending each char to the securestring using the AppendChar method.

you can use this simple script

private SecureString SecureStringConverter(string pass)
{
    SecureString ret = new SecureString();

    foreach (char chr in pass.ToCharArray())
        ret.AppendChar(chr);

    return ret;
}

The following 2 extensions should do the trick:

1. For a char array

   public static SecureString ToSecureString(this char[] _self)
   {
       SecureString knox = new SecureString();
       foreach (char c in _self)
       {
           knox.AppendChar(c);
       }
       return knox;
   }
   

2. And for string

   public static SecureString ToSecureString(this string _self)
   {
       SecureString knox = new SecureString();
       char[] chars = _self.ToCharArray();
       foreach (char c in chars)
       {
           knox.AppendChar(c);
       }
       return knox;
   }
   

Thanks to John Dagg for the AppendChar recommendation.

I'll throw this out there. Why?

You can't just change all your strings to secure strings and suddenly your application is "secure". Secure string is designed to keep the string encrypted for as long as possible, and only decrypted for a very short period of time, wiping the memory after an operation has been performed upon it.

I would hazard saying that you may have some design level issues to deal with before worrying about securing your application strings. Give us some more information on what your trying to do and we may be able to help better.

Here is a cheap linq trick.

            SecureString sec = new SecureString();
            string pwd = "abc123"; /* Not Secure! */
            pwd.ToCharArray().ToList().ForEach(sec.AppendChar);
            /* and now : seal the deal */
            sec.MakeReadOnly();

no fancy linq, not adding all the chars by hand, just plain and simple:

var str = "foo";
var sc = new SecureString();
foreach(char c in str) sc.appendChar(c);

There is also another way to convert between SecureString and String.

1. String to SecureString

SecureString theSecureString = new NetworkCredential("", "myPass").SecurePassword;

2. SecureString to String

string theString = new NetworkCredential("", theSecureString).Password;

Here is the link

I just want to point out to all the people saying, "That's not the point of SecureString", that many of the people asking this question might be in an application where, for whatever reason, justified or not, they are not particularly concerned about having a temporary copy of the password sit on the heap as a GC-able string, but they have to use an API that only accepts SecureString objects. So, you have an app where you don't care whether the password is on the heap, maybe it's internal-use only and the password is only there because it's required by the underlying network protocols, and you find that that string where the password is stored cannot be used to e.g. set up a remote PowerShell Runspace -- but there is no easy, straight-forward one-liner to create that SecureString that you need. It's a minor inconvenience -- but probably worth it to ensure that the applications that really do need SecureString don't tempt the authors to use System.String or System.Char[] intermediaries. :-)