/// <summary> /// Decode the Base64-encoded data in input and return the data in /// a new byte array. /// <p/> /// <para>The padding '=' characters at the end are considered optional, but /// if any are present, there must be the correct number of them. /// /// </para> /// </summary> /// <param name="input"> the data to decode </param> /// <param name="offset"> the position within the input array at which to start </param> /// <param name="len"> the number of bytes of input to decode </param> /// <param name="flags"> controls certain features of the decoded output. /// Pass {@code DEFAULT} to decode standard Base64. </param> /// <exception cref="IllegalArgumentException"> if the input contains /// incorrect padding </exception> public static byte[] decode(byte[] input, int offset, int len, int flags) { // Allocate space for the most data the input could represent. // (It could contain less if it contains whitespace, etc.) Decoder decoder = new Decoder(flags, new byte[len * 3 / 4]); if (!decoder.process(input, offset, len, true)) { throw new System.ArgumentException("bad base-64"); } // Maybe we got lucky and allocated exactly enough output space. if (decoder.op == decoder.output.Length) { return decoder.output; } // Need to shorten the array, so allocate a new one of the // right size and copy. byte[] temp = new byte[decoder.op]; Array.Copy(decoder.output, 0, temp, 0, decoder.op); return temp; }