mcs/class/corlib/System.Security.Policy/HashMembershipCondition.cs

   1 //
   2 // System.Security.Policy.HashMembershipCondition
   3 //
   4 // Authors:
   5 //      Jackson Harper (Jackson@LatitudeGeo.com)
   6 //      Sebastien Pouliot  <sebastien@ximian.com>
   7 //
   8 // (C) 2002 Jackson Harper, All rights reserved
   9 // Copyright (C) 2004 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 using System.Globalization;
  32 using System.Reflection;
  33 using System.Runtime.Serialization;
  34 using System.Security.Cryptography;
  35 using System.Text;
  36
  37 namespace System.Security.Policy {
  38
  39         [Serializable]
  40 #if NET_2_0
  41         public sealed class HashMembershipCondition : IMembershipCondition, ISecurityEncodable,
  42                 ISecurityPolicyEncodable, IDeserializationCallback, ISerializable {
  43 #else
  44         public sealed class HashMembershipCondition : IMembershipCondition, ISecurityEncodable,
  45                 ISecurityPolicyEncodable {
  46 #endif
  47                 private static readonly string XmlTag = "IMembershipCondition";
  48
  49                 private HashAlgorithm hash_algorithm;
  50                 private byte[] hash_value;
  51
  52                 // so System.Activator.CreateInstance can create an instance...
  53                 internal HashMembershipCondition ()
  54                 {
  55                 }
  56
  57                 public HashMembershipCondition (HashAlgorithm hash_algorithm, byte[] hash_value)
  58                 {
  59                         if (hash_algorithm == null)
  60                                 throw new ArgumentNullException ("hash_algorithm");
  61                         if (hash_value == null)
  62                                 throw new ArgumentNullException ("hash_value");
  63
  64                         this.hash_algorithm = hash_algorithm;
  65                         this.hash_value = hash_value;
  66                 }
  67
  68                 //
  69                 // Public Properties
  70                 //
  71
  72                 public HashAlgorithm HashAlgorithm {
  73                         get { return hash_algorithm; }
  74                         set {
  75                                 if (value == null)
  76                                         throw new ArgumentNullException ();
  77                                 hash_algorithm = value;
  78                         }
  79                 }
  80
  81                 public byte[] HashValue {
  82                         get { return hash_value; }
  83                         set {
  84                                 if (value == null)
  85                                         throw new ArgumentNullException ();
  86                                 hash_value = value;
  87                         }
  88                 }
  89
  90                 //
  91                 // Public Methods
  92                 //
  93
  94                 public bool Check (Evidence evidence)
  95                 {
  96                         if (evidence == null)
  97                                 throw new ArgumentNullException ("evidence");
  98
  99                         // Loop through evidence finding the first Hash object
 100                         foreach (object obj in evidence) {
 101                                 Hash hash = obj as Hash;
 102                                 if (hash == null)
 103                                         continue;
 104                                 if (EqualsHashValue (hash.GenerateHash (hash_algorithm)))
 105                                         return true;
 106                                 break;
 107                         }
 108                         return false;
 109                 }
 110
 111                 public IMembershipCondition Copy ()
 112                 {
 113                         return new HashMembershipCondition (hash_algorithm, hash_value);
 114                 }
 115
 116                 public override bool Equals (object o)
 117                 {
 118                         HashMembershipCondition other;
 119                         if (!(o is HashMembershipCondition))
 120                                 return false;
 121
 122                         other = (HashMembershipCondition)o;
 123
 124                         return (other.HashAlgorithm == hash_algorithm &&
 125                                 other.HashValue == hash_value);
 126                 }
 127
 128                 public SecurityElement ToXml()
 129                 {
 130                         return ToXml (null);
 131                 }
 132
 133                 public SecurityElement ToXml (PolicyLevel level)
 134                 {
 135                         SecurityElement se = new SecurityElement (XmlTag);
 136                         Type type = this.GetType ();
 137                         string classString = type.FullName + ", " + type.Assembly;
 138                         se.AddAttribute ("class", classString);
 139                         se.AddAttribute ("version", "1");
 140                         se.AddAttribute ("HashValue", Encoding.Default.GetString (hash_value));
 141                         se.AddAttribute ("HashAlgorithm", hash_algorithm.GetType ().FullName);
 142                         return se;
 143                 }
 144
 145                 public void FromXml (SecurityElement element)
 146                 {
 147                         FromXml (element, null);
 148                 }
 149
 150                 public void FromXml (SecurityElement e, PolicyLevel level)
 151                 {
 152                         if (e == null)
 153                                 throw new ArgumentNullException ("e");
 154                         if (e.Tag != XmlTag) {
 155                                 throw new ArgumentException ("e", Locale.GetText (
 156                                         "The Tag of SecurityElement must be " + XmlTag));
 157                         }
 158
 159                         string value = (string)e.Attributes ["HashValue"];
 160                         string algorithm = (string)e.Attributes ["HashAlgorithm"];
 161
 162                         if (value == null || algorithm == null ) {
 163                                 throw new ArgumentException ("e", Locale.GetText (
 164                                         "Missing either HashValue or HashAlgorithm"));
 165                         }
 166
 167                         hash_value = Encoding.Default.GetBytes (value);
 168                         hash_algorithm = (HashAlgorithm)Assembly.GetExecutingAssembly ().CreateInstance (algorithm);
 169
 170                 }
 171
 172                 public override int GetHashCode ()
 173                 {
 174                         return hash_value.GetHashCode ();
 175                 }
 176
 177                 public override string ToString ()
 178                 {
 179                         StringBuilder builder = new StringBuilder ();
 180                         Type alg_type = hash_algorithm.GetType ();
 181
 182                         builder.Append ("Hash -");
 183                         builder.AppendFormat ("{0} {1}", alg_type.FullName,
 184                                 alg_type.Assembly);
 185                         builder.AppendFormat (" = ",  Encoding.Default.GetString (hash_value));
 186
 187                         return builder.ToString ();
 188                 }
 189
 190                 //
 191                 // Private Methods
 192                 //
 193
 194                 private bool EqualsHashValue (byte[] value)
 195                 {
 196                         int len;
 197
 198                         if (value.Length != hash_value.Length)
 199                                 return false;
 200
 201                         len = value.Length;
 202                         for (int i=0; i<len; i++ ) {
 203                                 if (value[i] != hash_value[i])
 204                                         return false;
 205                         }
 206
 207                         return true;
 208                 }
 209
 210 #if NET_2_0
 211                 [MonoTODO]
 212                 void IDeserializationCallback.OnDeserialization (object sender)
 213                 {
 214                 }
 215
 216                 [MonoTODO]
 217                 void ISerializable.GetObjectData (SerializationInfo info, StreamingContext context)
 218                 {
 219                 }
 220 #endif
 221         }
 222 }
 223