// @nuget: DotNetZip

​

using Ionic.Zlib;

​

using System;

using System.IO;

using System.Text;

​

public static class DeflateStreamExtensions {

    public static UInt32 ReadUInt32(this DeflateStream stream) {

        int a = stream.ReadByte();

        int b = stream.ReadByte();

        return (UInt32)((a >> 8) + b);

    }

}

​

public static class GZipStreamExtensions {

    public static UInt32 ReadUInt32(this GZipStream stream) {

        int a = stream.ReadByte();

        int b = stream.ReadByte();

        return (UInt32)((a >> 8) + b);

    }

}

​

interface IDecoder {

    void Decode(Stream input, Stream output);

}

​

public sealed class Base85Decoder : IDecoder {

    private string _base85alphabet = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz!#$%()*+,-./:;=?@[]^_{}";

​

    public void Decode(Stream input, Stream output) {

            int inputSize = (int)input.Length;

            int i = 0;

            UInt32 value = 0;

            input.Seek(0, SeekOrigin.Begin);

​

            while (i < inputSize)

            {

                char c = (char)input.ReadByte();

                value = Convert.ToUInt32(_base85alphabet.IndexOf(c)) * Convert.ToUInt32(Math.Pow(85, 4));

                i += 1;

​

                if (i < inputSize)

                {

                    c = (char)input.ReadByte();

                    value += Convert.ToUInt32(_base85alphabet.IndexOf(c)) * Convert.ToUInt32(Math.Pow(85, 3));

                    i += 1;

                }

​

                if (i < inputSize)

                {

                    c = (char)input.ReadByte();

                    value += Convert.ToUInt32(_base85alphabet.IndexOf(c)) * Convert.ToUInt32(Math.Pow(85, 2));

                    i += 1;

                }

​

                if (i < inputSize)

                {

                    c = (char)input.ReadByte();

                    value += Convert.ToUInt32(_base85alphabet.IndexOf(c)) * Convert.ToUInt32(Math.Pow(85, 1));

                    i += 1;

                }

​

                if (i < inputSize)

                {

                    value += Convert.ToUInt32(_base85alphabet.IndexOf(c));

                    i += 1;

​

                    output.WriteByte(Convert.ToByte((value >> 24) & 0xFF));

                    output.WriteByte(Convert.ToByte((value >> 16) & 0xFF));

                    output.WriteByte(Convert.ToByte((value >> 8) & 0xFF));

                    output.WriteByte(Convert.ToByte(value & 0xFF));

                }

            }

​

            switch (inputSize % 5)

            {

                case 2:

                    value += 84 * 85 + 84;

                    output.WriteByte(Convert.ToByte((value >> 24) & 0xFF));

                    break;

                case 3:

                    value += 84 * Convert.ToUInt32(Math.Pow(85, 2)) + 84 * 85 + 84;

                    output.WriteByte(Convert.ToByte((value >> 24) & 0xFF));

                    output.WriteByte(Convert.ToByte((value >> 16) & 0xFF));

                    break;

                case 4:

                    value += 84;

                    output.WriteByte(Convert.ToByte((value >> 24) & 0xFF));

                    output.WriteByte(Convert.ToByte((value >> 16) & 0xFF));

                    output.WriteByte(Convert.ToByte((value >> 8) & 0xFF));

                    break;

                default:

                    break;

            }

​

            output.Seek(0, SeekOrigin.Begin);

    }

}

​

public class Program {

    public static void Main() {

        string str_in = "c-rMwTTj$L6h2+srIgDCmzW=CjUir:YF0o)jES;!Tf}4dy8617cG#]#wm2.{pN61Zp8Z3MzsxgJRu,ZjfqmOazRvlkGw00tdZwAll]Z!pO#B*#=ifTTy1x4v(fDW1s*2=@tZ3g7KC)bznhG$^*/KADlR@pY1H]ltnhvm@g)5hD!XZ[2wJc5fzR+(RwgJBnOsahR:/H+$vkxJCz_W38L{wq[/^{J$mFCq^dpa}RarALyQrU_mQz)9HHWfcMAtU+TNo6li9*f@zj7^;cmjv5x!rt;JVQ5DoF-lCDmTi,vLWVug?O=RGFiu7j+.S%2rMFTVvt(6.7}gj5]Qv;0HHdD9=pmGsnns5HI/)1P%O+LiwzUyP,@R8[L@0]*YtarFedjh/+^#M[J?7WjSSg4TH{vFCI,9yO2RxpAQMkwp7x}.j=]K-va3bEY;QT%zwNXPp]VoVQX7sbNDN@{qKzo3Eih[^xOUb2leKNt{Xp?B}o5$jq/h]0yDXaz_d%C,YUzwjHx,kMpwg#8B93p;^m{BiRgV{{o;mp7d=%pKgh$SQ5w@hjNqCG-9M]%DMv2!rmK1TB=XbzUYF9hf}w1j1UkDkI5WQ5Z!V*.]z#d7uKv7m6@.E[5MMYV3Ksa-xtoX=RvANqgiYwI/{BNjhnyNnFGzRz+Ej;ScCRhAS{z9M-R3oc;#R#s$4C2fZZ-y:]j7FKZGDr-c1=+sE9=l10?SnTm(QyrqgRvnY@hML6Hq^:#H;@md3FAQ#l;F@aw(LCd)tdb+bzkqJ2]5Lj?vuYYr#h3W@Y.-{(w{@7DOIhfOl%Eil9,z@iJ5}7w?wLaLoav5}A;x}oGSh!1rH^7+2d}QOkfxkbm%X#A02%PyH-UeZySDZRE}Vz0";

        using (MemoryStream input = new MemoryStream(Encoding.ASCII.GetBytes(str_in)))

        using (MemoryStream output = new MemoryStream())

        {

            /*output.WriteByte(0x1f);

            output.WriteByte(0x8b);

            output.WriteByte(0x08);

            output.WriteByte(0x00);

            output.WriteByte(0x00);

            output.WriteByte(0x00);

            output.WriteByte(0x00);

            output.WriteByte(0x00);

            output.WriteByte(0x00);

            output.WriteByte(0x0b);

            new Base85Decoder().Decode(input, output);

            output.WriteByte(0x0a);

            output.WriteByte(0x2a);

            output.WriteByte(0x82);

            output.WriteByte(0x2a);

            Console.WriteLine("output len = " + output.Length);

            byte[] compressed = output.ToArray();

            byte[] uncompressed = GZipStream.UncompressBuffer(compressed);*/

            new Base85Decoder().Decode(input, output);

            MemoryStream decompressed = new MemoryStream();

            using (ZlibStream ds = new ZlibStream(output, CompressionMode.Decompress)) {

                ds.CopyTo(decompressed);

            }

        }

    }

}