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) 2004-2007 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 #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
  63                 // Under 1.x this API requires a Local datetime to be provided
  64                 // Under 2.0 it will also accept a Utc datetime
  65                 static public ASN1 FromDateTime (DateTime dt)
  66                 {
  67                         if (dt.Year < 2050) {
  68                                 // UTCTIME
  69                                 return new ASN1 (0x17, Encoding.ASCII.GetBytes (
  70                                         dt.ToUniversalTime ().ToString ("yyMMddHHmmss",
  71                                         CultureInfo.InvariantCulture) + "Z"));
  72                         }
  73                         else {
  74                                 // GENERALIZEDTIME
  75                                 return new ASN1 (0x18, Encoding.ASCII.GetBytes (
  76                                         dt.ToUniversalTime ().ToString ("yyyyMMddHHmmss",
  77                                         CultureInfo.InvariantCulture) + "Z"));
  78                         }
  79                 }
  80
  81                 static public ASN1 FromInt32 (Int32 value)
  82                 {
  83                         byte[] integer = BitConverterLE.GetBytes (value);
  84                         Array.Reverse (integer);
  85                         int x = 0;
  86                         while ((x < integer.Length) && (integer [x] == 0x00))
  87                                 x++;
  88                         ASN1 asn1 = new ASN1 (0x02);
  89                         switch (x) {
  90                         case 0:
  91                                 asn1.Value = integer;
  92                                 break;
  93                         case 4:
  94                                 asn1.Value = new byte [1];
  95                                 break;
  96                         default:
  97                                 byte[] smallerInt = new byte [4 - x];
  98                                 Buffer.BlockCopy (integer, x, smallerInt, 0, smallerInt.Length);
  99                                 asn1.Value = smallerInt;
 100                                 break;
 101                         }
 102                         return asn1;
 103                 }
 104
 105                 static public ASN1 FromOid (string oid)
 106                 {
 107                         if (oid == null)
 108                                 throw new ArgumentNullException ("oid");
 109
 110                         return new ASN1 (CryptoConfig.EncodeOID (oid));
 111                 }
 112
 113                 static public ASN1 FromUnsignedBigInteger (byte[] big)
 114                 {
 115                         if (big == null)
 116                                 throw new ArgumentNullException ("big");
 117
 118                         // check for numbers that could be interpreted as negative (first bit)
 119                         if (big [0] >= 0x80) {
 120                                 // in thie cas we add a new, empty, byte (position 0) so we're
 121                                 // sure this will always be interpreted an unsigned integer.
 122                                 // However we can't feed it into RSAParameters or DSAParameters
 123                                 int length = big.Length + 1;
 124                                 byte[] uinteger = new byte [length];
 125                                 Buffer.BlockCopy (big, 0, uinteger, 1, length - 1);
 126                                 big = uinteger;
 127                         }
 128                         return new ASN1 (0x02, big);
 129                 }
 130
 131                 static public int ToInt32 (ASN1 asn1)
 132                 {
 133                         if (asn1 == null)
 134                                 throw new ArgumentNullException ("asn1");
 135                         if (asn1.Tag != 0x02)
 136                                 throw new FormatException ("Only integer can be converted");
 137
 138                         int x = 0;
 139                         for (int i=0; i < asn1.Value.Length; i++)
 140                                 x = (x << 8) + asn1.Value [i];
 141                         return x;
 142                 }
 143
 144                 // Convert a binary encoded OID to human readable string representation of
 145                 // an OID (IETF style). Based on DUMPASN1.C from Peter Gutmann.
 146                 static public string ToOid (ASN1 asn1)
 147                 {
 148                         if (asn1 == null)
 149                                 throw new ArgumentNullException ("asn1");
 150
 151                         byte[] aOID = asn1.Value;
 152                         StringBuilder sb = new StringBuilder ();
 153                         // Pick apart the OID
 154                         byte x = (byte) (aOID[0] / 40);
 155                         byte y = (byte) (aOID[0] % 40);
 156                         if (x > 2) {
 157                                 // Handle special case for large y if x = 2
 158                                 y += (byte) ((x - 2) * 40);
 159                                 x = 2;
 160                         }
 161                         sb.Append (x.ToString (CultureInfo.InvariantCulture));
 162                         sb.Append (".");
 163                         sb.Append (y.ToString (CultureInfo.InvariantCulture));
 164                         ulong val = 0;
 165                         for (x = 1; x < aOID.Length; x++) {
 166                                 val = ((val << 7) | ((byte) (aOID [x] & 0x7F)));
 167                                 if ( !((aOID [x] & 0x80) == 0x80)) {
 168                                         sb.Append (".");
 169                                         sb.Append (val.ToString (CultureInfo.InvariantCulture));
 170                                         val = 0;
 171                                 }
 172                         }
 173                         return sb.ToString ();
 174                 }
 175
 176                 static public DateTime ToDateTime (ASN1 time)
 177                 {
 178                         if (time == null)
 179                                 throw new ArgumentNullException ("time");
 180
 181                         string t = Encoding.ASCII.GetString (time.Value);
 182                         // to support both UTCTime and GeneralizedTime (and not so common format)
 183                         string mask = null;
 184                         int year;
 185                         bool utc = true;
 186                         switch (t.Length) {
 187                                 case 11:
 188                                         // illegal format, still it's supported for compatibility
 189                                         mask = "yyMMddHHmmZ";
 190                                         break;
 191                                 case 13:
 192                                         // RFC3280: 4.1.2.5.1  UTCTime
 193                                         year = Convert.ToInt16 (t.Substring (0, 2), CultureInfo.InvariantCulture);
 194                                         // Where YY is greater than or equal to 50, the
 195                                         // year SHALL be interpreted as 19YY; and
 196                                         // Where YY is less than 50, the year SHALL be
 197                                         // interpreted as 20YY.
 198                                         if (year >= 50)
 199                                                 t = "19" + t;
 200                                         else
 201                                                 t = "20" + t;
 202                                         mask = "yyyyMMddHHmmssZ";
 203                                         break;
 204                                 case 15:
 205                                         mask = "yyyyMMddHHmmssZ"; // GeneralizedTime
 206                                         break;
 207                                 case 17:
 208                                         // another illegal format (990630000000+1000), again supported for compatibility
 209                                         year = Convert.ToInt16 (t.Substring (0, 2), CultureInfo.InvariantCulture);
 210                                         string century = (year >= 50) ? "19" : "20";
 211                                         // ASN.1 (see ITU X.680 section 43.3) deals with offset differently than .NET
 212                                         char sign = (t[12] == '+') ? '-' : '+';
 213                                         t = String.Format ("{0}{1}{2}{3}{4}:{5}{6}", century, t.Substring (0, 12), sign,
 214                                                 t[13], t[14], t[15], t[16]);
 215                                         mask = "yyyyMMddHHmmsszzz";
 216                                         utc = false;
 217                                         break;
 218                         }
 219 #if NET_2_0
 220                         return DateTime.ParseExact (t, mask, null, DateTimeStyles.AdjustToUniversal);
 221 #else
 222                         DateTime result = DateTime.ParseExact (t, mask, null);
 223                         if (utc)
 224                                 return result;
 225                         return result.ToUniversalTime ();
 226 #endif
 227                 }
 228         }
 229 }