class/System/System.Security.Cryptography.X509Certificates/X509KeyUsageExtension.cs

   1 //
   2 // System.Security.Cryptography.X509Certificates.X509KeyUsageExtension
   3 //
   4 // Authors:
   5 //      Tim Coleman (tim@timcoleman.com)
   6 //      Sebastien Pouliot  <sebastien@ximian.com>
   7 //
   8 // Copyright (C) Tim Coleman, 2004
   9 // Copyright (C) 2004-2005 Novell Inc. (http://www.novell.com)
  10 //
  11 // Permission is hereby granted, free of charge, to any person obtaining
  12 // a copy of this software and associated documentation files (the
  13 // "Software"), to deal in the Software without restriction, including
  14 // without limitation the rights to use, copy, modify, merge, publish,
  15 // distribute, sublicense, and/or sell copies of the Software, and to
  16 // permit persons to whom the Software is furnished to do so, subject to
  17 // the following conditions:
  18 //
  19 // The above copyright notice and this permission notice shall be
  20 // included in all copies or substantial portions of the Software.
  21 //
  22 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  23 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  24 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  25 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  26 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  27 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  28 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  29 //
  30
  31 #if NET_2_0 && SECURITY_DEP
  32
  33 using System.Text;
  34
  35 using Mono.Security;
  36
  37 namespace System.Security.Cryptography.X509Certificates {
  38
  39         public sealed class X509KeyUsageExtension : X509Extension {
  40
  41                 internal const string oid = "2.5.29.15";
  42                 internal const string friendlyName = "Key Usage";
  43
  44                 internal const X509KeyUsageFlags all = X509KeyUsageFlags.EncipherOnly | X509KeyUsageFlags.CrlSign |
  45                         X509KeyUsageFlags.KeyCertSign | X509KeyUsageFlags.KeyAgreement | X509KeyUsageFlags.DataEncipherment |
  46                         X509KeyUsageFlags.KeyEncipherment | X509KeyUsageFlags.NonRepudiation |
  47                         X509KeyUsageFlags.DigitalSignature | X509KeyUsageFlags.DecipherOnly;
  48
  49                 private X509KeyUsageFlags _keyUsages;
  50                 private AsnDecodeStatus _status;
  51
  52                 // constructors
  53
  54                 public X509KeyUsageExtension ()
  55                 {
  56                         _oid = new Oid (oid, friendlyName);
  57                 }
  58
  59                 public X509KeyUsageExtension (AsnEncodedData encodedKeyUsage, bool critical)
  60                 {
  61                         // ignore the Oid provided by encodedKeyUsage (our rules!)
  62                         _oid = new Oid (oid, friendlyName);
  63                         _raw = encodedKeyUsage.RawData;
  64                         base.Critical = critical;
  65                         _status = Decode (this.RawData);
  66                 }
  67
  68                 public X509KeyUsageExtension (X509KeyUsageFlags keyUsages, bool critical)
  69                 {
  70                         _oid = new Oid (oid, friendlyName);
  71                         base.Critical = critical;
  72                         _keyUsages = GetValidFlags (keyUsages);
  73                         RawData = Encode ();
  74                 }
  75
  76                 // properties
  77
  78                 public X509KeyUsageFlags KeyUsages {
  79                         get {
  80                                 switch (_status) {
  81                                 case AsnDecodeStatus.Ok:
  82                                 case AsnDecodeStatus.InformationNotAvailable:
  83                                         return _keyUsages;
  84                                 default:
  85                                         throw new CryptographicException ("Badly encoded extension.");
  86                                 }
  87                         }
  88                 }
  89
  90                 // methods
  91
  92                 public override void CopyFrom (AsnEncodedData encodedData)
  93                 {
  94                         if (encodedData == null)
  95                                 throw new ArgumentNullException ("encodedData");
  96
  97                         X509Extension ex = (encodedData as X509Extension);
  98                         if (ex == null)
  99                                 throw new ArgumentException (Locale.GetText ("Wrong type."), "encodedData");
 100
 101                         if (ex._oid == null)
 102                                 _oid = new Oid (oid, friendlyName);
 103                         else
 104                                 _oid = new Oid (ex._oid);
 105
 106                         RawData = ex.RawData;
 107                         base.Critical = ex.Critical;
 108                         // and we deal with the rest later
 109                         _status = Decode (this.RawData);
 110                 }
 111
 112                 // internal
 113
 114                 internal X509KeyUsageFlags GetValidFlags (X509KeyUsageFlags flags)
 115                 {
 116                         if ((flags & all) != flags)
 117                                 return (X509KeyUsageFlags) 0;
 118                         return flags;
 119                 }
 120
 121                 internal AsnDecodeStatus Decode (byte[] extension)
 122                 {
 123                         if ((extension == null) || (extension.Length == 0))
 124                                 return AsnDecodeStatus.BadAsn;
 125                         if (extension [0] != 0x03)
 126                                 return AsnDecodeStatus.BadTag;
 127                         if (extension.Length < 3)
 128                                 return AsnDecodeStatus.BadLength;
 129                         if (extension.Length < 4)
 130                                 return AsnDecodeStatus.InformationNotAvailable;
 131
 132                         try {
 133                                 ASN1 ex = new ASN1 (extension);
 134                                 int kubits = 0;
 135                                 int i = 1; // byte zero has the number of unused bits (ASN1's BITSTRING)
 136                                 while (i < ex.Value.Length)
 137                                         kubits = (kubits << 8) + ex.Value [i++];
 138
 139                                 _keyUsages = GetValidFlags ((X509KeyUsageFlags)kubits);
 140                         }
 141                         catch {
 142                                 return AsnDecodeStatus.BadAsn;
 143                         }
 144
 145                         return AsnDecodeStatus.Ok;
 146                 }
 147
 148                 internal byte[] Encode ()
 149                 {
 150                         ASN1 ex = null;
 151                         int kubits = (int)_keyUsages;
 152                         byte empty = 0;
 153
 154                         if (kubits == 0) {
 155                                 ex = new ASN1 (0x03, new byte[] { empty });
 156                         } else {
 157                                 // count empty bits (applicable to first byte only)
 158                                 int ku = ((kubits < Byte.MaxValue) ? kubits : (kubits >> 8));
 159                                 while (((ku & 0x01) == 0x00) && (empty < 8)) {
 160                                         empty++;
 161                                         ku >>= 1;
 162                                 }
 163
 164                                 if (kubits <= Byte.MaxValue) {
 165                                         ex = new ASN1 (0x03, new byte[] { empty, (byte)kubits });
 166                                 } else {
 167                                         ex = new ASN1 (0x03, new byte[] { empty, (byte)kubits, (byte)(kubits >> 8) });
 168                                 }
 169                         }
 170
 171                         return ex.GetBytes ();
 172                 }
 173
 174                 internal override string ToString (bool multiLine)
 175                 {
 176                         switch (_status) {
 177                         case AsnDecodeStatus.BadAsn:
 178                                 return String.Empty;
 179                         case AsnDecodeStatus.BadTag:
 180                         case AsnDecodeStatus.BadLength:
 181                                 return FormatUnkownData (_raw);
 182                         case AsnDecodeStatus.InformationNotAvailable:
 183                                 return "Information Not Available";
 184                         }
 185
 186                         if (_oid.Value != oid)
 187                                 return String.Format ("Unknown Key Usage ({0})", _oid.Value);
 188                         if (_keyUsages == 0)
 189                                 return "Information Not Available";
 190
 191                         StringBuilder sb = new StringBuilder ();
 192
 193                         if ((_keyUsages & X509KeyUsageFlags.DigitalSignature) != 0) {
 194                                 sb.Append ("Digital Signature");
 195                         }
 196                         if ((_keyUsages & X509KeyUsageFlags.NonRepudiation) != 0) {
 197                                 if (sb.Length > 0)
 198                                         sb.Append (", ");
 199                                 sb.Append ("Non-Repudiation");
 200                         }
 201                         if ((_keyUsages & X509KeyUsageFlags.KeyEncipherment) != 0) {
 202                                 if (sb.Length > 0)
 203                                         sb.Append (", ");
 204                                 sb.Append ("Key Encipherment");
 205                         }
 206                         if ((_keyUsages & X509KeyUsageFlags.DataEncipherment) != 0) {
 207                                 if (sb.Length > 0)
 208                                         sb.Append (", ");
 209                                 sb.Append ("Data Encipherment");
 210                         }
 211                         if ((_keyUsages & X509KeyUsageFlags.KeyAgreement) != 0) {
 212                                 if (sb.Length > 0)
 213                                         sb.Append (", ");
 214                                 sb.Append ("Key Agreement");
 215                         }
 216                         if ((_keyUsages & X509KeyUsageFlags.KeyCertSign) != 0) {
 217                                 if (sb.Length > 0)
 218                                         sb.Append (", ");
 219                                 sb.Append ("Certificate Signing");
 220                         }
 221                         if ((_keyUsages & X509KeyUsageFlags.CrlSign) != 0) {
 222                                 if (sb.Length > 0)
 223                                         sb.Append (", ");
 224                                 sb.Append ("Off-line CRL Signing, CRL Signing");
 225                         }
 226                         if ((_keyUsages & X509KeyUsageFlags.EncipherOnly) != 0) {
 227                                 if (sb.Length > 0)
 228                                         sb.Append (", ");
 229                                 sb.Append ("Encipher Only");
 230                         }
 231                         if ((_keyUsages & X509KeyUsageFlags.DecipherOnly) != 0) {
 232                                 if (sb.Length > 0)
 233                                         sb.Append (", ");
 234                                 sb.Append ("Decipher Only");
 235                         }
 236
 237                         int ku = (int)_keyUsages;
 238                         sb.Append (" (");
 239                         sb.Append (((byte)ku).ToString ("x2"));
 240                         if (ku > Byte.MaxValue) {
 241                                 sb.Append (" ");
 242                                 sb.Append (((byte)(ku >> 8)).ToString ("x2"));
 243                         }
 244                         sb.Append (")");
 245
 246                         if (multiLine)
 247                                 sb.Append (Environment.NewLine);
 248
 249                         return sb.ToString ();
 250                 }
 251         }
 252 }
 253
 254 #endif