GetSessionKey.cs

private static byte[] GetSessionKey(byte[] sharedSecret)
{
    String salt = PlayerPrefs.GetString(_PlayerPrefs.Salt);
    if(String.IsNullOrEmpty(salt))
    {
        throw new PlayerPrefsItemNotFoundException(_PlayerPrefs.Salt);
    }
    var pdb = new Pkcs5S2ParametersGenerator(new Sha256Digest());
    pdb.Init(sharedSecret, Conversion.StringToByteArray(salt), CryptoConstant.Iterations);
    var key = (KeyParameter)pdb.GenerateDerivedMacParameters(CryptoConstant.KdfKeySize * 8);
    return key.GetKey();
}