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// Copyright (C) 2014, Kenneth Skovhede
// http://www.hexad.dk, opensource@hexad.dk
//
// This library is free software; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; either version 2.1 of the
// License, or (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
using System;
using System.Collections.Generic;
using System.Security.Cryptography;
using Duplicati.Library.Interface;
using Duplicati.Library.Utility;
using System.Text;
using System.Linq;
namespace Duplicati.Library.Backend
{
public class KeyGenerator : IWebModule
{
private const string KEY_TYPE_NAME = "key-type";
private const string KEY_USERNAME = "key-username";
private const string KEY_KEYLEN = "key-bits";
private const string KEY_TEMPLATE_DSA = "-----BEGIN DSA PRIVATE KEY-----\n{0}\n-----END DSA PRIVATE KEY----- \n";
private const string KEY_TEMPLATE_RSA = "-----BEGIN RSA PRIVATE KEY-----\n{0}\n-----END RSA PRIVATE KEY----- \n";
private const string PUB_KEY_FORMAT_DSA = "ssh-dss";
private const string PUB_KEY_FORMAT_RSA = "ssh-rsa";
private const string KEYTYPE_DSA = "dsa";
private const string KEYTYPE_RSA = "rsa";
private readonly string DEFAULT_USERNAME = "backup-user@" + System.Environment.MachineName;
private const string DEFAULT_KEYTYPE = KEYTYPE_DSA;
private const int DEFAULT_KEYLEN = 1024;
private static void EncodePEMLength(System.IO.Stream s, uint length)
{
s.WriteByte((byte)((length >> 24) & 0xff));
s.WriteByte((byte)((length >> 16) & 0xff));
s.WriteByte((byte)((length >> 8) & 0xff));
s.WriteByte((byte)(length & 0xff));
}
private static void EncodeDERLength(System.IO.Stream s, uint length)
{
if (length < 0x7f)
{
s.WriteByte((byte)length);
}
else if (length <= 0x7fff)
{
s.WriteByte(0x82);
s.WriteByte((byte)((length >> 8) & 0xff));
s.WriteByte((byte)(length & 0xff));
}
else
{
s.WriteByte(0x84);
s.WriteByte((byte)((length >> 24) & 0xff));
s.WriteByte((byte)((length >> 16) & 0xff));
s.WriteByte((byte)((length >> 8) & 0xff));
s.WriteByte((byte)(length & 0xff));
}
}
private static byte[] EncodeDER(byte[][] data)
{
byte[] payload;
using(var ms = new System.IO.MemoryStream())
{
foreach(var b in data)
{
ms.WriteByte(0x02);
var isNegative = (b[0] & 0x80) != 0;
EncodeDERLength(ms, (uint)(b.Length + (isNegative ? 1 : 0)));
if (isNegative)
ms.WriteByte(0);
ms.Write(b, 0, b.Length);
}
payload = ms.ToArray();
}
using(var ms = new System.IO.MemoryStream())
{
ms.WriteByte(0x30);
EncodeDERLength(ms, (uint)payload.Length);
ms.Write(payload, 0, payload.Length);
return ms.ToArray();
}
}
private static byte[] EncodePEM(byte[][] data)
{
using(var ms = new System.IO.MemoryStream())
{
foreach(var n in data)
{
var isNegative = (n[0] & 0x80) != 0;
EncodePEMLength(ms, (uint)(n.Length + (isNegative ? 1 : 0)));
if (isNegative)
ms.WriteByte(0);
ms.Write(n, 0, n.Length);
}
return ms.ToArray();
}
}
private static IDictionary<string, string> OutputKey(byte[] private_key, byte[] public_key, string pem_template, string key_name, string username)
{
var res = new Dictionary<string, string>();
var b64_raw = Convert.ToBase64String(private_key);
var sb = new StringBuilder();
for(var i = 0; i < b64_raw.Length; i += 80)
{
sb.Append(b64_raw.Substring(i, Math.Min(80, b64_raw.Length - i)));
sb.Append("\n");
}
var b64 = sb.ToString().Trim();
var pem = string.Format(pem_template, b64);
var uri = SSHv2.KEYFILE_URI + Duplicati.Library.Utility.Uri.UrlEncode(pem);
var pub = key_name + " " + Convert.ToBase64String(public_key) + " " + username;
res["privkey"] = b64_raw;
res["privkeyfile"] = pem;
res["privkeyuri"] = uri;
res["pubkey"] = pub;
return res;
}
#region IWebModule implementation
public IDictionary<string, string> Execute(IDictionary<string, string> options)
{
string keytype;
if (!options.TryGetValue(KEY_TYPE_NAME, out keytype))
keytype = DEFAULT_KEYTYPE;
string username;
if (!options.TryGetValue(KEY_USERNAME, out username))
username = DEFAULT_USERNAME;
string keylen_s;
if (!options.TryGetValue(KEY_KEYLEN, out keylen_s))
keylen_s = "0";
int keylen;
if (!int.TryParse(keylen_s, out keylen))
keylen = DEFAULT_KEYLEN;
if (KEYTYPE_RSA.Equals(keytype, StringComparison.InvariantCultureIgnoreCase))
{
var rsa = RSACryptoServiceProvider.Create();
if (keylen > 0)
rsa.KeySize = keylen;
else
rsa.KeySize = DEFAULT_KEYLEN;
var key = rsa.ExportParameters(true);
var privateEntries = new byte[][] { new byte[]{ 0x0 }, key.Modulus, key.Exponent, key.D, key.P, key.Q, key.DP, key.DQ, key.InverseQ };
var publicEntries = new byte[][] {
System.Text.Encoding.ASCII.GetBytes(PUB_KEY_FORMAT_RSA),
key.Exponent,
key.Modulus
};
return OutputKey(EncodeDER(privateEntries), EncodePEM(publicEntries), KEY_TEMPLATE_RSA, PUB_KEY_FORMAT_RSA, username);
}
else if (KEYTYPE_DSA.Equals(keytype, StringComparison.InvariantCultureIgnoreCase))
{
var dsa = DSACryptoServiceProvider.Create();
if (keylen > 0)
dsa.KeySize = keylen;
else
dsa.KeySize = DEFAULT_KEYLEN;
var key = dsa.ExportParameters(true);
var privateEntries = new byte[][] { new byte[] { 0x0 }, key.P, key.Q, key.G, key.Y, key.X };
var publicEntries = new byte[][] {
System.Text.Encoding.ASCII.GetBytes(PUB_KEY_FORMAT_DSA),
key.P,
key.Q,
key.G,
key.Y
};
return OutputKey(EncodeDER(privateEntries), EncodePEM(publicEntries), KEY_TEMPLATE_DSA, PUB_KEY_FORMAT_DSA, username);
}
else
{
throw new Exception(string.Format("Unsupported key type: {0}", keytype));
}
}
public string Key { get { return "ssh-keygen"; } }
public string DisplayName { get { return Strings.KeyGenerator.DisplayName; } }
public string Description { get { return Strings.KeyGenerator.Description; } }
public IList<ICommandLineArgument> SupportedCommands
{
get
{
return new List<ICommandLineArgument>(new ICommandLineArgument[] {
new CommandLineArgument(KEY_KEYLEN, CommandLineArgument.ArgumentType.Integer, Strings.KeyGenerator.KeyLenShort, Strings.KeyGenerator.KeyLenLong, DEFAULT_KEYLEN.ToString(), null, new string[] {"1024", "2048"}),
new CommandLineArgument(KEY_TYPE_NAME, CommandLineArgument.ArgumentType.Enumeration, Strings.KeyGenerator.KeyTypeShort, Strings.KeyGenerator.KeyTypeLong, DEFAULT_KEYTYPE, null, new string[] {KEYTYPE_DSA, KEYTYPE_RSA}),
new CommandLineArgument(KEY_USERNAME, CommandLineArgument.ArgumentType.Integer, Strings.KeyGenerator.KeyUsernameShort, Strings.KeyGenerator.KeyUsernameLong, DEFAULT_USERNAME),
});
}
}
#endregion
}
}
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