System.Security.Cryptography.Rfc2898DeriveBytes.GetBytes C# (CSharp) Method

        public override byte[] GetBytes(int cb)
        {
            if (cb <= 0)
                throw new ArgumentOutOfRangeException(nameof(cb), SR.ArgumentOutOfRange_NeedPosNum);
            byte[] password = new byte[cb];

            int offset = 0;
            int size = _endIndex - _startIndex;
            if (size > 0)
            {
                if (cb >= size)
                {
                    Buffer.BlockCopy(_buffer, _startIndex, password, 0, size);
                    _startIndex = _endIndex = 0;
                    offset += size;
                }
                else
                {
                    Buffer.BlockCopy(_buffer, _startIndex, password, 0, cb);
                    _startIndex += cb;
                    return password;
                }
            }

            Debug.Assert(_startIndex == 0 && _endIndex == 0, "Invalid start or end index in the internal buffer.");

            while (offset < cb)
            {
                byte[] T_block = Func();
                int remainder = cb - offset;
                if (remainder > BlockSize)
                {
                    Buffer.BlockCopy(T_block, 0, password, offset, BlockSize);
                    offset += BlockSize;
                }
                else
                {
                    Buffer.BlockCopy(T_block, 0, password, offset, remainder);
                    offset += remainder;
                    Buffer.BlockCopy(T_block, remainder, _buffer, _startIndex, BlockSize - remainder);
                    _endIndex += (BlockSize - remainder);
                    return password;
                }
            }
            return password;
        }

        public static string Criptografar(string texto)
        {
            if(string.IsNullOrEmpty(texto))
                return String.Empty;

            string outStr;

            RijndaelManaged aesAlg = null;
            try
            {
                var key = new Rfc2898DeriveBytes(Segredo, Complemento);
                aesAlg = new RijndaelManaged();
                aesAlg.Key = key.GetBytes(aesAlg.KeySize / 8);
                aesAlg.IV = key.GetBytes(aesAlg.BlockSize / 8);
                var encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);
                using (var msEncrypt = new MemoryStream())
                {
                    using (var csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                    {
                        using (var swEncrypt = new StreamWriter(csEncrypt))
                        {
                            swEncrypt.Write(texto);
                        }
                    }
                    outStr = Convert.ToBase64String(msEncrypt.ToArray());
                }
            }
            finally
            {
                if (aesAlg != null)
                    aesAlg.Clear();
            }
            return outStr;
        }