class/Mono.Security/Mono.Security.Authenticode/PrivateKey.cs

   1 //
   2 // PrivateKey.cs - Private Key (PVK) Format Implementation
   3 //
   4 // Author:
   5 //      Sebastien Pouliot <sebastien@ximian.com>
   6 //
   7 // (C) 2003 Motus Technologies Inc. (http://www.motus.com)
   8 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
   9 //
  10 // Permission is hereby granted, free of charge, to any person obtaining
  11 // a copy of this software and associated documentation files (the
  12 // "Software"), to deal in the Software without restriction, including
  13 // without limitation the rights to use, copy, modify, merge, publish,
  14 // distribute, sublicense, and/or sell copies of the Software, and to
  15 // permit persons to whom the Software is furnished to do so, subject to
  16 // the following conditions:
  17 //
  18 // The above copyright notice and this permission notice shall be
  19 // included in all copies or substantial portions of the Software.
  20 //
  21 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  22 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  23 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  24 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  25 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  26 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  27 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  28 //
  29
  30 using System;
  31 using System.Globalization;
  32 using System.IO;
  33 using System.Security.Cryptography;
  34 using System.Text;
  35
  36 using Mono.Security.Cryptography;
  37
  38 namespace Mono.Security.Authenticode {
  39
  40         // References:
  41         // a.   http://www.drh-consultancy.demon.co.uk/pvk.html
  42
  43         public class PrivateKey {
  44
  45                 private const uint magic = 0xb0b5f11e;
  46
  47                 private bool encrypted;
  48                 private RSA rsa;
  49                 private bool weak;
  50                 private int keyType;
  51
  52                 public PrivateKey ()
  53                 {
  54                         keyType = 2;    // required for MS makecert !!!
  55                 }
  56
  57                 public PrivateKey (byte[] data, string password)
  58                 {
  59                         if (data == null)
  60                                 throw new ArgumentNullException ("data");
  61
  62                         if (!Decode (data, password)) {
  63                                 throw new CryptographicException (
  64                                         Locale.GetText ("Invalid data and/or password"));
  65                         }
  66                 }
  67
  68                 public bool Encrypted {
  69                         get { return encrypted; }
  70                 }
  71
  72                 public int KeyType {
  73                         get { return keyType; }
  74                         set { keyType = value; }
  75                 }
  76
  77                 public RSA RSA {
  78                         get { return rsa; }
  79                         set { rsa = value; }
  80                 }
  81
  82                 public bool Weak {
  83                         get { return ((encrypted) ? weak : true); }
  84                         set { weak = value; }
  85                 }
  86
  87                 private byte[] DeriveKey (byte[] salt, string password)
  88                 {
  89                         byte[] pwd = Encoding.ASCII.GetBytes (password);
  90                         SHA1 sha1 = (SHA1)SHA1.Create ();
  91                         sha1.TransformBlock (salt, 0, salt.Length, salt, 0);
  92                         sha1.TransformFinalBlock (pwd, 0, pwd.Length);
  93                         byte[] key = new byte [16];
  94                         Buffer.BlockCopy (sha1.Hash, 0, key, 0, 16);
  95                         sha1.Clear ();
  96                         Array.Clear (pwd, 0, pwd.Length);
  97                         return key;
  98                 }
  99
 100                 private bool Decode (byte[] pvk, string password)
 101                 {
 102                         // DWORD magic
 103                         if (BitConverterLE.ToUInt32 (pvk, 0) != magic)
 104                                 return false;
 105                         // DWORD reserved
 106                         if (BitConverterLE.ToUInt32 (pvk, 4) != 0x0)
 107                                 return false;
 108                         // DWORD keytype
 109                         keyType = BitConverterLE.ToInt32 (pvk, 8);
 110                         // DWORD encrypted
 111                         encrypted = (BitConverterLE.ToUInt32 (pvk, 12) == 1);
 112                         // DWORD saltlen
 113                         int saltlen = BitConverterLE.ToInt32 (pvk, 16);
 114                         // DWORD keylen
 115                         int keylen = BitConverterLE.ToInt32 (pvk, 20);
 116                         byte[] keypair = new byte [keylen];
 117                         Buffer.BlockCopy (pvk, 24 + saltlen, keypair, 0, keylen);
 118                         // read salt (if present)
 119                         if (saltlen > 0) {
 120                                 if (password == null)
 121                                         return false;
 122
 123                                 byte[] salt = new byte [saltlen];
 124                                 Buffer.BlockCopy (pvk, 24, salt, 0, saltlen);
 125                                 // first try with full (128) bits
 126                                 byte[] key = DeriveKey (salt, password);
 127                                 // decrypt in place and try this
 128                                 RC4 rc4 = RC4.Create ();
 129                                 ICryptoTransform dec = rc4.CreateDecryptor (key, null);
 130                                 dec.TransformBlock (keypair, 8, keypair.Length - 8, keypair, 8);
 131                                 try {
 132                                         rsa = CryptoConvert.FromCapiPrivateKeyBlob (keypair);
 133                                         weak = false;
 134                                 }
 135                                 catch (CryptographicException) {
 136                                         weak = true;
 137                                         // second chance using weak crypto
 138                                         Buffer.BlockCopy (pvk, 24 + saltlen, keypair, 0, keylen);
 139                                         // truncate the key to 40 bits
 140                                         Array.Clear (key, 5, 11);
 141                                         // decrypt
 142                                         RC4 rc4b = RC4.Create ();
 143                                         dec = rc4b.CreateDecryptor (key, null);
 144                                         dec.TransformBlock (keypair, 8, keypair.Length - 8, keypair, 8);
 145                                         rsa = CryptoConvert.FromCapiPrivateKeyBlob (keypair);
 146                                 }
 147                                 Array.Clear (key, 0, key.Length);
 148                         }
 149                         else  {
 150                                 weak = true;
 151                                 // read unencrypted keypair
 152                                 rsa = CryptoConvert.FromCapiPrivateKeyBlob (keypair);
 153                                 Array.Clear (keypair, 0, keypair.Length);
 154                         }
 155
 156                         // zeroize pvk (which could contain the unencrypted private key)
 157                         Array.Clear (pvk, 0, pvk.Length);
 158
 159                         return (rsa != null);
 160                 }
 161
 162                 public void Save (string filename)
 163                 {
 164                         Save (filename, null);
 165                 }
 166
 167                 public void Save (string filename, string password)
 168                 {
 169                         if (filename == null)
 170                                 throw new ArgumentNullException ("filename");
 171
 172                         byte[] blob = null;
 173                         FileStream fs = File.Open (filename, FileMode.Create, FileAccess.Write);
 174                         try {
 175                                 // header
 176                                 byte[] empty = new byte [4];
 177                                 byte[] data = BitConverterLE.GetBytes (magic);
 178                                 fs.Write (data, 0, 4);  // magic
 179                                 fs.Write (empty, 0, 4); // reserved
 180                                 data = BitConverterLE.GetBytes (keyType);
 181                                 fs.Write (data, 0, 4);  // key type
 182
 183                                 encrypted = (password != null);
 184                                 blob = CryptoConvert.ToCapiPrivateKeyBlob (rsa);
 185                                 if (encrypted) {
 186                                         data = BitConverterLE.GetBytes (1);
 187                                         fs.Write (data, 0, 4);  // encrypted
 188                                         data = BitConverterLE.GetBytes (16);
 189                                         fs.Write (data, 0, 4);  // saltlen
 190                                         data = BitConverterLE.GetBytes (blob.Length);
 191                                         fs.Write (data, 0, 4);          // keylen
 192
 193                                         byte[] salt = new byte [16];
 194                                         RC4 rc4 = RC4.Create ();
 195                                         byte[] key = null;
 196                                         try {
 197                                                 // generate new salt (16 bytes)
 198                                                 RandomNumberGenerator rng = RandomNumberGenerator.Create ();
 199                                                 rng.GetBytes (salt);
 200                                                 fs.Write (salt, 0, salt.Length);
 201                                                 key = DeriveKey (salt, password);
 202                                                 if (Weak)
 203                                                         Array.Clear (key, 5, 11);
 204                                                 ICryptoTransform enc = rc4.CreateEncryptor (key, null);
 205                                                 // we don't encrypt the header part of the BLOB
 206                                                 enc.TransformBlock (blob, 8, blob.Length - 8, blob, 8);
 207                                         }
 208                                         finally {
 209                                                 Array.Clear (salt, 0, salt.Length);
 210                                                 Array.Clear (key, 0, key.Length);
 211                                                 rc4.Clear ();
 212                                         }
 213                                 }
 214                                 else {
 215                                         fs.Write (empty, 0, 4); // encrypted
 216                                         fs.Write (empty, 0, 4); // saltlen
 217                                         data = BitConverterLE.GetBytes (blob.Length);
 218                                         fs.Write (data, 0, 4);          // keylen
 219                                 }
 220
 221                                 fs.Write (blob, 0, blob.Length);
 222                         }
 223                         finally {
 224                                 // BLOB may include an uncrypted keypair
 225                                 Array.Clear (blob, 0, blob.Length);
 226                                 fs.Close ();
 227                         }
 228                 }
 229
 230                 static public PrivateKey CreateFromFile (string filename)
 231                 {
 232                         return CreateFromFile (filename, null);
 233                 }
 234
 235                 static public PrivateKey CreateFromFile (string filename, string password)
 236                 {
 237                         if (filename == null)
 238                                 throw new ArgumentNullException ("filename");
 239
 240                         byte[] pvk = null;
 241                         using (FileStream fs = File.Open (filename, FileMode.Open, FileAccess.Read, FileShare.Read)) {
 242                                 pvk = new byte [fs.Length];
 243                                 fs.Read (pvk, 0, pvk.Length);
 244                                 fs.Close ();
 245                         }
 246                         return new PrivateKey (pvk, password);
 247                 }
 248         }
 249 }