SHA1 with salt on windows phone 7 - windows-phone-7

Question

I have some some time now reshearchd how to encode a password to SHA1 with a salt.
The is the code i used on my web application part, but it will not work on a phone environment.
public class Password
{
private string _password;
private int _salt;
public Password(string strPassword, int nSalt)
{
_password = strPassword;
_salt = nSalt;
}
public string ComputeSaltedHash()
{
// Create Byte array of password string
ASCIIEncoding encoder = new ASCIIEncoding();
Byte[] _secretBytes = encoder.GetBytes(_password);
// Create a new salt
Byte[] _saltBytes = new Byte[4];
_saltBytes[0] = (byte)(_salt >> 24);
_saltBytes[1] = (byte)(_salt >> 16);
_saltBytes[2] = (byte)(_salt >> 8);
_saltBytes[3] = (byte)(_salt);
// append the two arrays
Byte[] toHash = new Byte[_secretBytes.Length + _saltBytes.Length];
Array.Copy(_secretBytes, 0, toHash, 0, _secretBytes.Length);
Array.Copy(_saltBytes, 0, toHash, _secretBytes.Length, _saltBytes.Length);
SHA1 sha1 = SHA1.Create();
Byte[] computedHash = sha1.ComputeHash(toHash);
return encoder.GetString(computedHash);
}
public static int CreateRandomSalt()
{
Byte[] _saltBytes = new Byte[4];
RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();
rng.GetBytes(_saltBytes);
return ((((int)_saltBytes[0]) << 24) + (((int)_saltBytes[1]) << 16) +
(((int)_saltBytes[2]) << 8) + ((int)_saltBytes[3]));
}
public static string CreateRandomPassword(int PasswordLength)
{
String _allowedChars = "abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNOPQRSTUVWXYZ23456789!\"#¤%&/()=?$+-_.,;'*";
Byte[] randomBytes = new Byte[PasswordLength];
RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();
rng.GetBytes(randomBytes);
char[] chars = new char[PasswordLength];
int allowedCharCount = _allowedChars.Length;
for (int i = 0; i < PasswordLength; i++)
{
chars[i] = _allowedChars[(int)randomBytes[i] % allowedCharCount];
}
return new string(chars);
}
}

Answer 1

Silverlight and Windows Phone 7 do not have an ASCIIEncoding. I suggest you use the UTF8Encoding instead. If you are certain that your passwords are always within the ASCII range then this encoding will work the same as the ASCIIEncoding would of had it been present.
If on the other hand you cannot guarantee that passwords are always within the ASCII range then you would need to make sure both ends hash using the UTF8Encoding to ensure generated hashs are the same.