mcs/class/corlib/Mono.Security/ASN1Convert.cs

   1 //
   2 // ASN1Convert.cs: Abstract Syntax Notation 1 convertion routines
   3 //
   4 // Authors:
   5 //      Sebastien Pouliot  <sebastien@ximian.com>
   6 //      Jesper Pedersen  <jep@itplus.dk>
   7 //
   8 // (C) 2003 Motus Technologies Inc. (http://www.motus.com)
   9 // (C) 2004 IT+ A/S (http://www.itplus.dk)
  10 // Copyright (C) 2004-2005 Novell, Inc (http://www.novell.com)
  11 //
  12 // Permission is hereby granted, free of charge, to any person obtaining
  13 // a copy of this software and associated documentation files (the
  14 // "Software"), to deal in the Software without restriction, including
  15 // without limitation the rights to use, copy, modify, merge, publish,
  16 // distribute, sublicense, and/or sell copies of the Software, and to
  17 // permit persons to whom the Software is furnished to do so, subject to
  18 // the following conditions:
  19 //
  20 // The above copyright notice and this permission notice shall be
  21 // included in all copies or substantial portions of the Software.
  22 //
  23 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  27 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  28 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  29 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  30 //
  31
  32 using System;
  33 using System.Collections;
  34 using System.Globalization;
  35 using System.Security.Cryptography;
  36 using System.Text;
  37
  38 namespace Mono.Security {
  39
  40         // References:
  41         // a.   ITU ASN.1 standards (free download)
  42         //      http://www.itu.int/ITU-T/studygroups/com17/languages/
  43
  44 #if INSIDE_CORLIB
  45         internal
  46 #else
  47         public
  48 #endif
  49 #if NET_2_0
  50         static class ASN1Convert {
  51 #else
  52         sealed class ASN1Convert {
  53
  54                 private ASN1Convert ()
  55                 {
  56                 }
  57 #endif
  58                 // RFC3280, section 4.2.1.5
  59                 // CAs conforming to this profile MUST always encode certificate
  60                 // validity dates through the year 2049 as UTCTime; certificate validity
  61                 // dates in 2050 or later MUST be encoded as GeneralizedTime.
  62                 static public ASN1 FromDateTime (DateTime dt)
  63                 {
  64                         if (dt.Year < 2050) {
  65                                 // UTCTIME
  66                                 return new ASN1 (0x17, Encoding.ASCII.GetBytes (
  67                                         dt.ToUniversalTime ().ToString ("yyMMddHHmmss",
  68                                         CultureInfo.InvariantCulture) + "Z"));
  69                         }
  70                         else {
  71                                 // GENERALIZEDTIME
  72                                 return new ASN1 (0x18, Encoding.ASCII.GetBytes (
  73                                         dt.ToUniversalTime ().ToString ("yyyyMMddHHmmss",
  74                                         CultureInfo.InvariantCulture) + "Z"));
  75                         }
  76                 }
  77
  78                 static public ASN1 FromInt32 (Int32 value)
  79                 {
  80                         byte[] integer = BitConverterLE.GetBytes (value);
  81                         Array.Reverse (integer);
  82                         int x = 0;
  83                         while ((x < integer.Length) && (integer [x] == 0x00))
  84                                 x++;
  85                         ASN1 asn1 = new ASN1 (0x02);
  86                         switch (x) {
  87                         case 0:
  88                                 asn1.Value = integer;
  89                                 break;
  90                         case 4:
  91                                 asn1.Value = new byte [1];
  92                                 break;
  93                         default:
  94                                 byte[] smallerInt = new byte [4 - x];
  95                                 Buffer.BlockCopy (integer, x, smallerInt, 0, smallerInt.Length);
  96                                 asn1.Value = smallerInt;
  97                                 break;
  98                         }
  99                         return asn1;
 100                 }
 101
 102                 static public ASN1 FromOid (string oid)
 103                 {
 104                         if (oid == null)
 105                                 throw new ArgumentNullException ("oid");
 106
 107                         return new ASN1 (CryptoConfig.EncodeOID (oid));
 108                 }
 109
 110                 static public ASN1 FromUnsignedBigInteger (byte[] big)
 111                 {
 112                         if (big == null)
 113                                 throw new ArgumentNullException ("big");
 114
 115                         // check for numbers that could be interpreted as negative (first bit)
 116                         if (big [0] >= 0x80) {
 117                                 // in thie cas we add a new, empty, byte (position 0) so we're
 118                                 // sure this will always be interpreted an unsigned integer.
 119                                 // However we can't feed it into RSAParameters or DSAParameters
 120                                 int length = big.Length + 1;
 121                                 byte[] uinteger = new byte [length];
 122                                 Buffer.BlockCopy (big, 0, uinteger, 1, length - 1);
 123                                 big = uinteger;
 124                         }
 125                         return new ASN1 (0x02, big);
 126                 }
 127
 128                 static public int ToInt32 (ASN1 asn1)
 129                 {
 130                         if (asn1 == null)
 131                                 throw new ArgumentNullException ("asn1");
 132                         if (asn1.Tag != 0x02)
 133                                 throw new FormatException ("Only integer can be converted");
 134
 135                         int x = 0;
 136                         for (int i=0; i < asn1.Value.Length; i++)
 137                                 x = (x << 8) + asn1.Value [i];
 138                         return x;
 139                 }
 140
 141                 // Convert a binary encoded OID to human readable string representation of
 142                 // an OID (IETF style). Based on DUMPASN1.C from Peter Gutmann.
 143                 static public string ToOid (ASN1 asn1)
 144                 {
 145                         if (asn1 == null)
 146                                 throw new ArgumentNullException ("asn1");
 147
 148                         byte[] aOID = asn1.Value;
 149                         StringBuilder sb = new StringBuilder ();
 150                         // Pick apart the OID
 151                         byte x = (byte) (aOID[0] / 40);
 152                         byte y = (byte) (aOID[0] % 40);
 153                         if (x > 2) {
 154                                 // Handle special case for large y if x = 2
 155                                 y += (byte) ((x - 2) * 40);
 156                                 x = 2;
 157                         }
 158                         sb.Append (x.ToString (CultureInfo.InvariantCulture));
 159                         sb.Append (".");
 160                         sb.Append (y.ToString (CultureInfo.InvariantCulture));
 161                         ulong val = 0;
 162                         for (x = 1; x < aOID.Length; x++) {
 163                                 val = ((val << 7) | ((byte) (aOID [x] & 0x7F)));
 164                                 if ( !((aOID [x] & 0x80) == 0x80)) {
 165                                         sb.Append (".");
 166                                         sb.Append (val.ToString (CultureInfo.InvariantCulture));
 167                                         val = 0;
 168                                 }
 169                         }
 170                         return sb.ToString ();
 171                 }
 172
 173                 static public DateTime ToDateTime (ASN1 time)
 174                 {
 175                         if (time == null)
 176                                 throw new ArgumentNullException ("time");
 177
 178                         string t = Encoding.ASCII.GetString (time.Value);
 179                         // to support both UTCTime and GeneralizedTime (and not so common format)
 180                         string mask = null;
 181                         switch (t.Length) {
 182                                 case 11:
 183                                         mask = "yyMMddHHmmZ"; // illegal I think ... must check
 184                                         break;
 185                                 case 13:
 186                                         // RFC3280: 4.1.2.5.1  UTCTime
 187                                         int year = Convert.ToInt16 (t.Substring (0, 2), CultureInfo.InvariantCulture);
 188                                         // Where YY is greater than or equal to 50, the
 189                                         // year SHALL be interpreted as 19YY; and
 190                                         // Where YY is less than 50, the year SHALL be
 191                                         // interpreted as 20YY.
 192                                         if (year >= 50)
 193                                                 t = "19" + t;
 194                                         else
 195                                                 t = "20" + t;
 196                                         mask = "yyyyMMddHHmmssZ";
 197                                         break;
 198                                 case 15:
 199                                         mask = "yyyyMMddHHmmssZ"; // GeneralizedTime
 200                                         break;
 201                         }
 202                         return DateTime.ParseExact (t, mask, null);
 203                 }
 204         }
 205 }