class/System/System.Security.Cryptography.X509Certificates/X509SubjectKeyIdentifierExtension.cs

   1 //
   2 // System.Security.Cryptography.X509Certificates.X509SubjectKeyIdentifierExtension
   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 using Mono.Security.Cryptography;
  37
  38 namespace System.Security.Cryptography.X509Certificates {
  39
  40         public sealed class X509SubjectKeyIdentifierExtension : X509Extension {
  41
  42                 internal const string oid = "2.5.29.14";
  43                 internal const string friendlyName = "Subject Key Identifier";
  44
  45                 private byte[] _subjectKeyIdentifier;
  46                 private string _ski;
  47                 private AsnDecodeStatus _status;
  48
  49                 // constructors
  50
  51                 public X509SubjectKeyIdentifierExtension ()
  52                 {
  53                         _oid = new Oid (oid, friendlyName);
  54                 }
  55
  56                 public X509SubjectKeyIdentifierExtension (AsnEncodedData encodedSubjectKeyIdentifier, bool critical)
  57                 {
  58                         // ignore the Oid provided by encodedKeyUsage (our rules!)
  59                         _oid = new Oid (oid, friendlyName);
  60                         _raw = encodedSubjectKeyIdentifier.RawData;
  61                         base.Critical = critical;
  62                         _status = Decode (this.RawData);
  63                 }
  64
  65                 public X509SubjectKeyIdentifierExtension (byte[] subjectKeyIdentifier, bool critical)
  66                 {
  67                         if (subjectKeyIdentifier == null)
  68                                 throw new ArgumentNullException ("subjectKeyIdentifier");
  69                         if (subjectKeyIdentifier.Length == 0)
  70                                 throw new ArgumentException ("subjectKeyIdentifier");
  71
  72                         _oid = new Oid (oid, friendlyName);
  73                         base.Critical = critical;
  74                         _subjectKeyIdentifier = (byte[])subjectKeyIdentifier.Clone ();
  75                         RawData = Encode ();
  76                 }
  77
  78                 public X509SubjectKeyIdentifierExtension (string subjectKeyIdentifier, bool critical)
  79                 {
  80                         if (subjectKeyIdentifier == null)
  81                                 throw new ArgumentNullException ("subjectKeyIdentifier");
  82                         if (subjectKeyIdentifier.Length < 2)
  83                                 throw new ArgumentException ("subjectKeyIdentifier");
  84
  85                         _oid = new Oid (oid, friendlyName);
  86                         base.Critical = critical;
  87                         _subjectKeyIdentifier = FromHex (subjectKeyIdentifier);
  88                         RawData = Encode ();
  89                 }
  90
  91                 public X509SubjectKeyIdentifierExtension (PublicKey key, bool critical)
  92                         : this (key, X509SubjectKeyIdentifierHashAlgorithm.Sha1, critical)
  93                 {
  94                 }
  95
  96                 public X509SubjectKeyIdentifierExtension (PublicKey key, X509SubjectKeyIdentifierHashAlgorithm algorithm, bool critical)
  97                 {
  98                         if (key == null)
  99                                 throw new ArgumentNullException ("key");
 100
 101                         byte[] pkraw = key.EncodedKeyValue.RawData;
 102                         // compute SKI
 103                         switch (algorithm) {
 104                         // hash of the public key, excluding Tag, Length and unused bits values
 105                         case X509SubjectKeyIdentifierHashAlgorithm.Sha1:
 106                                 _subjectKeyIdentifier = SHA1.Create ().ComputeHash (pkraw);
 107                                 break;
 108                         // 0100 bit pattern followed by the 60 last bit of the hash
 109                         case X509SubjectKeyIdentifierHashAlgorithm.ShortSha1:
 110                                 byte[] hash = SHA1.Create ().ComputeHash (pkraw);
 111                                 _subjectKeyIdentifier = new byte [8];
 112                                 Buffer.BlockCopy (hash, 12, _subjectKeyIdentifier, 0, 8);
 113                                 _subjectKeyIdentifier [0] = (byte) (0x40 | (_subjectKeyIdentifier [0] & 0x0F));
 114                                 break;
 115                         // hash of the public key, including Tag, Length and unused bits values
 116                         case X509SubjectKeyIdentifierHashAlgorithm.CapiSha1:
 117                                 // CryptoAPI does that hash on the complete subjectPublicKeyInfo (unlike PKIX)
 118                                 // http://groups.google.ca/groups?selm=e7RqM%24plCHA.1488%40tkmsftngp02&oe=UTF-8&output=gplain
 119                                 ASN1 subjectPublicKeyInfo = new ASN1 (0x30);
 120                                 ASN1 algo = subjectPublicKeyInfo.Add (new ASN1 (0x30));
 121                                 algo.Add (new ASN1 (CryptoConfig.EncodeOID (key.Oid.Value)));
 122                                 algo.Add (new ASN1 (key.EncodedParameters.RawData));
 123                                 // add an extra byte for the unused bits (none)
 124                                 byte[] full = new byte [pkraw.Length + 1];
 125                                 Buffer.BlockCopy (pkraw, 0, full, 1, pkraw.Length);
 126                                 subjectPublicKeyInfo.Add (new ASN1 (0x03, full));
 127                                 _subjectKeyIdentifier = SHA1.Create ().ComputeHash (subjectPublicKeyInfo.GetBytes ());
 128                                 break;
 129                         default:
 130                                 throw new ArgumentException ("algorithm");
 131                         }
 132
 133                         _oid = new Oid (oid, friendlyName);
 134                         base.Critical = critical;
 135                         RawData = Encode ();
 136                 }
 137
 138                 // properties
 139
 140                 public string SubjectKeyIdentifier {
 141                         get {
 142                                 switch (_status) {
 143                                 case AsnDecodeStatus.Ok:
 144                                 case AsnDecodeStatus.InformationNotAvailable:
 145                                         if (_subjectKeyIdentifier != null)
 146                                                 _ski = CryptoConvert.ToHex (_subjectKeyIdentifier);
 147                                         return _ski;
 148                                 default:
 149                                         throw new CryptographicException ("Badly encoded extension.");
 150                                 }
 151                         }
 152                 }
 153
 154                 // methods
 155
 156                 public override void CopyFrom (AsnEncodedData encodedData)
 157                 {
 158                         if (encodedData == null)
 159                                 throw new ArgumentNullException ("encodedData");
 160
 161                         X509Extension ex = (encodedData as X509Extension);
 162                         if (ex == null)
 163                                 throw new ArgumentException (Locale.GetText ("Wrong type."), "encodedData");
 164
 165                         if (ex._oid == null)
 166                                 _oid = new Oid (oid, friendlyName);
 167                         else
 168                                 _oid = new Oid (ex._oid);
 169
 170                         RawData = ex.RawData;
 171                         base.Critical = ex.Critical;
 172                         // and we deal with the rest later
 173                         _status = Decode (this.RawData);
 174                 }
 175
 176                 // internal
 177
 178                 static internal byte FromHexChar (char c)
 179                 {
 180                         if ((c >= 'a') && (c <= 'f'))
 181                                 return (byte) (c - 'a' + 10);
 182                         if ((c >= 'A') && (c <= 'F'))
 183                                 return (byte) (c - 'A' + 10);
 184                         if ((c >= '0') && (c <= '9'))
 185                                 return (byte) (c - '0');
 186                         return 255;     // F
 187                 }
 188
 189                 static internal byte FromHexChars (char c1, char c2)
 190                 {
 191                         byte result = FromHexChar (c1);
 192                         if (result < 255)
 193                                 result = (byte) ((result << 4) | FromHexChar (c2));
 194                         return result;
 195                 }
 196
 197                 static internal byte[] FromHex (string hex)
 198                 {
 199                         // here we can't use CryptoConvert.FromHex because we
 200                         // must convert any *illegal* (non hex) 2 characters
 201                         // to 'FF' and ignore last char on odd length
 202                         if (hex == null)
 203                                 return null;
 204
 205                         int length = hex.Length >> 1;
 206
 207                         byte[] result = new byte [length]; // + (odd ? 1 : 0)];
 208                         int n = 0;
 209                         int i = 0;
 210                         while (n < length) {
 211                                 result [n++] = FromHexChars (hex [i++], hex [i++]);
 212                         }
 213                         return result;
 214                 }
 215
 216                 internal AsnDecodeStatus Decode (byte[] extension)
 217                 {
 218                         if ((extension == null) || (extension.Length == 0))
 219                                 return AsnDecodeStatus.BadAsn;
 220                         _ski = String.Empty;
 221                         if (extension [0] != 0x04)
 222                                 return AsnDecodeStatus.BadTag;
 223                         if (extension.Length == 2)
 224                                 return AsnDecodeStatus.InformationNotAvailable;
 225                         if (extension.Length < 3)
 226                                 return AsnDecodeStatus.BadLength;
 227
 228                         try {
 229                                 ASN1 ex = new ASN1 (extension);
 230                                 _subjectKeyIdentifier = ex.Value;
 231                         }
 232                         catch {
 233                                 return AsnDecodeStatus.BadAsn;
 234                         }
 235
 236                         return AsnDecodeStatus.Ok;
 237                 }
 238
 239                 internal byte[] Encode ()
 240                 {
 241                         ASN1 ex = new ASN1 (0x04, _subjectKeyIdentifier);
 242                         return ex.GetBytes ();
 243                 }
 244
 245                 internal override string ToString (bool multiLine)
 246                 {
 247                         switch (_status) {
 248                         case AsnDecodeStatus.BadAsn:
 249                                 return String.Empty;
 250                         case AsnDecodeStatus.BadTag:
 251                         case AsnDecodeStatus.BadLength:
 252                                 return FormatUnkownData (_raw);
 253                         case AsnDecodeStatus.InformationNotAvailable:
 254                                 return "Information Not Available";
 255                         }
 256
 257                         if (_oid.Value != oid)
 258                                 return String.Format ("Unknown Key Usage ({0})", _oid.Value);
 259
 260                         StringBuilder sb = new StringBuilder ();
 261
 262                         for (int i=0; i < _subjectKeyIdentifier.Length; i++) {
 263                                 sb.Append (_subjectKeyIdentifier [i].ToString ("x2"));
 264                                 if (i != _subjectKeyIdentifier.Length - 1)
 265                                         sb.Append (" ");
 266                         }
 267
 268                         if (multiLine)
 269                                 sb.Append (Environment.NewLine);
 270
 271                         return sb.ToString ();
 272                 }
 273         }
 274 }
 275
 276 #endif