OpenSshKeyWriter.cs

/*
* Copyright (C) 2013 Christian Hoffmeister
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see {http://www.gnu.org/licenses/}.
*/
using System;
using System.IO;
using System.Text;

namespace CoreCI.Common
{
    internal class OpenSshKeyWriter : IDisposable
    {
        private readonly Stream stream;

        public OpenSshKeyWriter(Stream stream)
        {
            this.stream = stream;
        }

        public void Dispose()
        {
            this.stream.Dispose();
        }

        public void WriteMultiPrecisionInteger(byte[] i)
        {
            bool isLeadingBitSet = (i[0] & 128) != 0;
            int length = isLeadingBitSet ? i.Length + 1 : i.Length;

            this.WriteInt32(length);

            // prepend a 0-byte to make the integer positive
            if (isLeadingBitSet)
                this.stream.WriteByte(0);
            this.stream.Write(i, 0, i.Length);
        }

        public void WriteDerMultiPrecisionInteger(byte[] i)
        {
            bool isLeadingBitSet = (i[0] & 128) != 0;
            int length = isLeadingBitSet ? i.Length + 1 : i.Length;

            // 0x02 marks an upcoming integer in DER format
            this.stream.WriteByte(2);
            this.WriteDerLength(length);

            // prepend a 0-byte to make the integer positive
            if (isLeadingBitSet)
                this.stream.WriteByte(0);
            this.stream.Write(i, 0, i.Length);
        }

        public void WriteDerLength(int length)
        {
            if (length > 127)
            {
                int num = 1;
                int num2 = length;
                while ((num2 >>= 8) != 0)
                {
                    num++;
                }

                byte[] array = new byte[num + 1];
                array[0] = (byte)(num | 128);
                int i = (num - 1) * 8;
                int num3 = 1;
                while (i >= 0)
                {
                    array[num3] = (byte)(length >> i);
                    i -= 8;
                    num3++;
                }

                this.stream.Write(array, 0, array.Length);
            }
            else
            {
                this.stream.WriteByte((byte)length);
            }
        }

        public void WriteInt32(int i)
        {
            byte[] bytes = new byte[4];

            bytes[0] = (byte)((i >> 24) & 255);
            bytes[1] = (byte)((i >> 16) & 255);
            bytes[2] = (byte)((i >> 8) & 255);
            bytes[3] = (byte)((i >> 0) & 255);

            this.stream.Write(bytes, 0, 4);
        }

        public void WriteString(string str)
        {
            byte[] bytes = Encoding.ASCII.GetBytes(str);

            this.stream.Write(bytes, 0, bytes.Length);
        }

        public void WriteByte(byte b)
        {
            this.stream.WriteByte(b);
        }
    }
}