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