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) 2004-2007 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         static class ASN1Convert {
  50                 // RFC3280, section 4.2.1.5
  51                 // CAs conforming to this profile MUST always encode certificate
  52                 // validity dates through the year 2049 as UTCTime; certificate validity
  53                 // dates in 2050 or later MUST be encoded as GeneralizedTime.
  54
  55                 // Under 1.x this API requires a Local datetime to be provided
  56                 // Under 2.0 it will also accept a Utc datetime
  57                 static public ASN1 FromDateTime (DateTime dt)
  58                 {
  59                         if (dt.Year < 2050) {
  60                                 // UTCTIME
  61                                 return new ASN1 (0x17, Encoding.ASCII.GetBytes (
  62                                         dt.ToUniversalTime ().ToString ("yyMMddHHmmss",
  63                                         CultureInfo.InvariantCulture) + "Z"));
  64                         }
  65                         else {
  66                                 // GENERALIZEDTIME
  67                                 return new ASN1 (0x18, Encoding.ASCII.GetBytes (
  68                                         dt.ToUniversalTime ().ToString ("yyyyMMddHHmmss",
  69                                         CultureInfo.InvariantCulture) + "Z"));
  70                         }
  71                 }
  72
  73                 static public ASN1 FromInt32 (Int32 value)
  74                 {
  75                         byte[] integer = BitConverterLE.GetBytes (value);
  76                         Array.Reverse (integer);
  77                         int x = 0;
  78                         while ((x < integer.Length) && (integer [x] == 0x00))
  79                                 x++;
  80                         ASN1 asn1 = new ASN1 (0x02);
  81                         switch (x) {
  82                         case 0:
  83                                 asn1.Value = integer;
  84                                 break;
  85                         case 4:
  86                                 asn1.Value = new byte [1];
  87                                 break;
  88                         default:
  89                                 byte[] smallerInt = new byte [4 - x];
  90                                 Buffer.BlockCopy (integer, x, smallerInt, 0, smallerInt.Length);
  91                                 asn1.Value = smallerInt;
  92                                 break;
  93                         }
  94                         return asn1;
  95                 }
  96
  97                 static public ASN1 FromOid (string oid)
  98                 {
  99                         if (oid == null)
 100                                 throw new ArgumentNullException ("oid");
 101
 102                         return new ASN1 (CryptoConfig.EncodeOID (oid));
 103                 }
 104
 105                 static public ASN1 FromUnsignedBigInteger (byte[] big)
 106                 {
 107                         if (big == null)
 108                                 throw new ArgumentNullException ("big");
 109
 110                         // check for numbers that could be interpreted as negative (first bit)
 111                         if (big [0] >= 0x80) {
 112                                 // in thie cas we add a new, empty, byte (position 0) so we're
 113                                 // sure this will always be interpreted an unsigned integer.
 114                                 // However we can't feed it into RSAParameters or DSAParameters
 115                                 int length = big.Length + 1;
 116                                 byte[] uinteger = new byte [length];
 117                                 Buffer.BlockCopy (big, 0, uinteger, 1, length - 1);
 118                                 big = uinteger;
 119                         }
 120                         return new ASN1 (0x02, big);
 121                 }
 122
 123                 static public int ToInt32 (ASN1 asn1)
 124                 {
 125                         if (asn1 == null)
 126                                 throw new ArgumentNullException ("asn1");
 127                         if (asn1.Tag != 0x02)
 128                                 throw new FormatException ("Only integer can be converted");
 129
 130                         int x = 0;
 131                         for (int i=0; i < asn1.Value.Length; i++)
 132                                 x = (x << 8) + asn1.Value [i];
 133                         return x;
 134                 }
 135
 136                 // Convert a binary encoded OID to human readable string representation of
 137                 // an OID (IETF style). Based on DUMPASN1.C from Peter Gutmann.
 138                 static public string ToOid (ASN1 asn1)
 139                 {
 140                         if (asn1 == null)
 141                                 throw new ArgumentNullException ("asn1");
 142
 143                         byte[] aOID = asn1.Value;
 144                         StringBuilder sb = new StringBuilder ();
 145                         // Pick apart the OID
 146                         byte x = (byte) (aOID[0] / 40);
 147                         byte y = (byte) (aOID[0] % 40);
 148                         if (x > 2) {
 149                                 // Handle special case for large y if x = 2
 150                                 y += (byte) ((x - 2) * 40);
 151                                 x = 2;
 152                         }
 153                         sb.Append (x.ToString (CultureInfo.InvariantCulture));
 154                         sb.Append (".");
 155                         sb.Append (y.ToString (CultureInfo.InvariantCulture));
 156                         ulong val = 0;
 157                         for (x = 1; x < aOID.Length; x++) {
 158                                 val = ((val << 7) | ((byte) (aOID [x] & 0x7F)));
 159                                 if ( !((aOID [x] & 0x80) == 0x80)) {
 160                                         sb.Append (".");
 161                                         sb.Append (val.ToString (CultureInfo.InvariantCulture));
 162                                         val = 0;
 163                                 }
 164                         }
 165                         return sb.ToString ();
 166                 }
 167
 168                 static public DateTime ToDateTime (ASN1 time)
 169                 {
 170                         if (time == null)
 171                                 throw new ArgumentNullException ("time");
 172
 173                         string t = Encoding.ASCII.GetString (time.Value);
 174                         // to support both UTCTime and GeneralizedTime (and not so common format)
 175                         string mask = null;
 176                         int year;
 177                         switch (t.Length) {
 178                                 case 11:
 179                                         // illegal format, still it's supported for compatibility
 180                                         mask = "yyMMddHHmmZ";
 181                                         break;
 182                                 case 13:
 183                                         // RFC3280: 4.1.2.5.1  UTCTime
 184                                         year = Convert.ToInt16 (t.Substring (0, 2), CultureInfo.InvariantCulture);
 185                                         // Where YY is greater than or equal to 50, the
 186                                         // year SHALL be interpreted as 19YY; and
 187                                         // Where YY is less than 50, the year SHALL be
 188                                         // interpreted as 20YY.
 189                                         if (year >= 50)
 190                                                 t = "19" + t;
 191                                         else
 192                                                 t = "20" + t;
 193                                         mask = "yyyyMMddHHmmssZ";
 194                                         break;
 195                                 case 15:
 196                                         mask = "yyyyMMddHHmmssZ"; // GeneralizedTime
 197                                         break;
 198                                 case 17:
 199                                         // another illegal format (990630000000+1000), again supported for compatibility
 200                                         year = Convert.ToInt16 (t.Substring (0, 2), CultureInfo.InvariantCulture);
 201                                         string century = (year >= 50) ? "19" : "20";
 202                                         // ASN.1 (see ITU X.680 section 43.3) deals with offset differently than .NET
 203                                         char sign = (t[12] == '+') ? '-' : '+';
 204                                         t = String.Format ("{0}{1}{2}{3}{4}:{5}{6}", century, t.Substring (0, 12), sign,
 205                                                 t[13], t[14], t[15], t[16]);
 206                                         mask = "yyyyMMddHHmmsszzz";
 207                                         break;
 208                         }
 209                         return DateTime.ParseExact (t, mask, CultureInfo.InvariantCulture, DateTimeStyles.AdjustToUniversal);
 210                 }
 211         }
 212 }